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Installed K3EXREF

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Edward R Cole

Installed K3EXREF

Rick,

For the majority who only do CW/SSB on HF, adding the EXREF is
probably unnecessary. The TCXO-3 holds the K3 within 14-Hz on
28-MHz. The EXREF improves that by an order of magnitude to 1.4 Hz.

This becomes necessary for some digital modes like JT-65. That is
mainly used on eme on 144 and higher bands. If you operate on the
microwave bands oscillator error is mulitplied so that is becomes
hard to get much freq. accuracy or stability. On 1296 I use a
transverter that has an external locked PLL LO. That keeps it within
1-Hz. Typically one would not have better than a few KHz with a xtal
oscillator on 105.67 MHz multiplied x12 = 1268 MHz. Getting the
accuracy on the transverter LO without also having it on 28-MHz IF
radio is kind of being only "Half-done". With the K3 EXREF my
combined 1296 freq. will equal that of the K3. That is important
when eme signals are so weak they cannot be detected by ear. Add
frequency errors to that and the task becomes very tough.

Now consider doing that at 10-GHz. A few of us with K3's are mw'ers
and/or eme'rs so the accuracy is very important to us.

Sidenote: Use of 10-MHz WWV is nearly impossible if you run a 10-MHz
station reference oscillator. I have a mw freq.counter that uses a
rubidium external reference. I use it to check the frequency of my
10-MHz OCXO which I run thru a 4-way distribution amp to feed things
in the shack:
1) K3EXTREF
2) 144/28 Transverter (DEMI)
3) 1296/28 Transverter (DEMI)
4) future item

The OCXO was bought off e-bay for $39.99+shipping, and is very
stabile but does drift over months so I "tweak" it back to the
Rubidium about 4 times a year. It runs 24/7 on a battery supply
floated by a charger.

All can be seen on my website (including newly added instructions for
adding sub-Rx IF Out).
73, Ed - KL7UW

------------------------------
Message: 33
Date: Sun, 20 Mar 2011 14:45:59 +0000
From: Rick Stealey <[hidden email]>
Subject: Re: [Elecraft] Installed K3EXREF
To: <[hidden email]>

Excellent posting by W9AC, a great reference, to be saved.
Now I wonder if it would be possible for someone to enlighten me as to
the need for such extreme accuracy? Is it because my K3 reads out to 1 Hz
but I can't really believe the absolute accuracy of that number unless I
get a K3EXREF? But if that is the case, my question would still remain,
wouldn't it?
Not that I need something else to put on my list ahead of my P3 and
sub receiver.
Rick K2XT

73, Ed - KL7UW, WD2XSH/45
======================================
BP40IQ 500 KHz - 10-GHz www.kl7uw.com
EME: 144-1.4kw, 432-100w, 1296-testing*, 3400-winter?
DUBUS Magazine USA Rep [hidden email]
======================================
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P.B. Christensen

Re: Installed K3EXREF

In reply to this post by Jack Smith-6

Another benefit of the GPS-DO is that routine calibration to ensure
long-term accuracy is the responsibility of the U.S. Department of Defense,
and funded by U.S. tax payers. Unless there's a hardware-related problem
with the GPS-DO, calibration is someone else's problem and expense. The
user need only care that the unit has attained "Lock" status.

Paul, W9AC

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Matt Zilmer

Re: Installed K3EXREF

In reply to this post by Rick Stealey

The K3EXREF is in field test now, as far as I know. It might be a
little while before Elecraft puts it up for sale.

"Extreme accuracy" probably has two psychological and one scientific
source:
- The need to put the K3 dead-on frequency is reassuring to folks that
aren't sure it stays that way mostly as-is with the TCXO.
- The desire to be a frequency authority, and be able to help others
when they're off-freq. Hams with older rigs sometimes end up shifted
off freq. On HF, I hear this a lot.
- Knowing exactly what frequency you're on helps with band-edge
issues, for example between the Extra-only CW sub-bands and the
general CW sub-band. With a 1 Hz readout, this is seldom a problem,
but it gets even better when the last digit also indicates the actual
carrier freq.

The K3 with just the stock TCXO holds the reference at somewhere below
1 PPM anyway. This is probably accurate enough for almost everyone,
but some want near-perfect accuracy. GPS time has an uncertainty of
around 0.3 nS, which is pretty low compared to 1PPM. No TCXO can beat
that, but maybe an OCXO can?

73,
matt W6NIA

On Sun, 20 Mar 2011 14:45:59 +0000, you wrote:

>
>
>Excellent posting by W9AC, a great reference, to be saved.
>Now I wonder if it would be possible for someone to enlighten me as to
>the need for such extreme accuracy? Is it because my K3 reads out to 1 Hz
>but I can't really believe the absolute accuracy of that number unless I
>get a K3EXREF? But if that is the case, my question would still remain,
>wouldn't it?
>Not that I need something else to put on my list ahead of my P3 and
>sub receiver.
>Rick K2XT
>
>______________________________________________________________
>Elecraft mailing list
>Home: http://mailman.qth.net/mailman/listinfo/elecraft
>Help: http://mailman.qth.net/mmfaq.htm
>Post: mailto:[hidden email]
>
>This list hosted by: http://www.qsl.net
>Please help support this email list: http://www.qsl.net/donate.html

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Jerry Muller

Re: Installed K3EXREF

In reply to this post by P.B. Christensen

This was an excellent explanation.

I got a Trimble Thunderbolt off eBay for less than 200 bucks. It came from
China and came with an antenna and power supply. If you are going to get one
of the ones that come from China, make sure you get the power supply with
it. The domestic Thunderbolts have a unipolar supply but the ones from China
were specials and require a special bipolar power supply. As long as you're
getting the power supply with it, you're OK. I have not noticed any noise
from the power supply from China. I expect ferrites may solve the problem if
found.

It works just fine with the stock Thunderbolt software. I've had mine for
about 6 months and I've run tests using the Thunderbolt software. The PC
monitoring software allows you to monitor the errors detected and log them.
The accuracy is quite good. Although I see occasional errors greater than 1
part in 10^9, most of the measured errors are far less than 1 part in 10^9.
I can't find any of the spreadsheets I generated (from many hours of
operation) right now but I seem to recall that 1 sigma was down around 1
part in 10^10. This translates into a 1 Hz error at 10 GHz. The +/- 1 Hz
error in the K3 is much greater than the accuracy of the GPSDO

My primary reason for getting the GPSDO was for microwave and EME
operations. Being able to use it with the K3 is a plus. I'm likely to be an
early adopter of the production units when they become available. I will
probably order my second K3 with a K3EXREF.

Jerry - K0TV

----- Original Message -----
From: "Paul Christensen" <[hidden email]>
To: <[hidden email]>
Sent: Saturday, March 19, 2011 9:34 PM
Subject: Re: [Elecraft] Installed K3EXREF

>I installed it on Friday in about 30 minutes, but I'm comfortable with my
> way around the K3. I would think that most users could install it in
> about
> an hour or less. Installation is actually very simple with very few parts
> involved. K3EXREF came with an SMA connector and SMA to BNC
> between-series
> adapter.
>
> Performance is exactly as promised by Elecraft. Although K3EXREF will not
> phase lock the K3 to the external frequency source, I'm finding that it
> stays within 1 Hz on 20m when locked to CHU at 14.670 MHz. I'm also
> finding that testing for zero-beat to WWV at 10 MHz is not a good idea in
> my
> shack, and perhaps yours too. There are many 10 MHz signals being emitted
> by nearby appliances, LAN routers, security system, Ethernet boards, etc.
> That common, even frequency is everywhere in a household these days.
>
> In much of North America, CHU is an excellent source for testing since it
> keeps cesium accuracy like WWV but the odd frequency of CHU is a real
> benefit since the chance for beating against extraneous signals is much
> smaller than at 10 MHz. Testing at a higher frequency rather than say the
> MW broadcast band also provides for a reasonably good account of how the
> K3EXREF performs. After installation, I would also suggest not trying to
> test zero beat K3EXREF against commercial MW or SW BC stations since their
> carriers are allowed to deviate much more than the cesium-based time and
> frequency standards of CHU and WWV. Commercial AM broadcast station
> frequencies are typically only accurate to about +/- 20 Hz although most
> are
> better than that.
>
> The K3's 49 MHz oscillator is only adjusted at intervals between 4 and 8
> seconds by K3EXREF in order to minimize jitter. The K3 retains its
> original
> phase noise performance since the external reference is not used internal
> to
> the K3's frequency generating scheme. Think of it this way -- K3EXREF is
> like lightly touching the 49 MHz oscillator with a feather every few
> seconds
> if necessary to keep it within 1 Hz or so. Also, the K3 frequency stays
> accurate even at the moment of powering up the K3. Kinda' fun to watch
> the
> 49 MHz oscillator display change during warm-up as it's being corrected
> and
> compared against the external reference.
>
> External references: There are three primary types, and all can be
> purchased for less than USD $150 on the used market. Cesium standards (a
> fourth type) are also available but are generally much more expensive,
> complicated, and won't offer any benefit to K3 users since K3EXREF limits
> resolution and accuracy to about 1 Hz.
>
> The first type is the GPS Disciplined Oscillator (GPS-DO). This type of
> standard locks itself onto the visible GPS satellites orbiting the sky.
> Requires a GPS antenna and is self-calibrating to the GPS satellites. The
> GPS-DO's time and frequency averages from the visible satellites, each
> satellite having it's own on-board cesium-based oscillator. Long-term
> accuracy is usually good to at least 1 x 10^-11. Extreme accuracy and
> only
> a magnitude or two behind cesium. Look for Hewlett-Packard Z3801A,
> Z3816A,
> Trimble Thunderbolt, Brandywine, Symmetricon, and Datum models. Short
> list,
> but many others available.
>
> Rubidium is the next type. No GPS tracking needed. Accuracy commensurate
> with GPS-DO. No antenna required. Long-term performance is highly
> dependent on the quality of the optical beam from the rubidium pump lamp.
> Look for EF Efratom, Datum,
>
> Third, is a high quality oven-controlled crystal oscillator (OCXO).
> Requires periodic calibration. Accuracy good to at least +/- 0.05 ppm and
> offer the best phase noise performance among the three types of
> oscillators,
> but as noted earlier, the excellent phase noise attributes of the OCXO
> will
> not be carried over to the K3.
>
> A shack reference oscillator is good for use with other equipment too
> (e.g.,
> frequency counter). Although a bit lossy, I currectly use a
> Mini-Circuits
> passive three-way splitter, but one can purchase a distribution amp to
> feed
> many pieces of equipment from a single oscillator. Unlike the splitter, a
> DA offers unity gain and very high port isolation.
>
> Finally, be mindful that most GPS-DO and rubidium units use internal
> switch-mode DC-DC converters. Switching noise was bad enough on two of my
> units that I decided to gut the converters and used an outboard
> triple-output linear supply. The Trimble Thunderbolts that have been
> retired from the cellular industry require an external triple-output
> supply.
> If choosing this model, get a linear type and avoid the headaches.
>
> Paul, W9AC
>
> ______________________________________________________________
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>
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Jerry Muller

Re: Installed K3EXREF

In reply to this post by Matt Zilmer

Speaking of band edges....

During the recent ARRL DX SSB contest, there was a station operating on
7127. Because of the lower SB extending to 7124 (assuming 3k bandwidth) he
was operating out of the US phone band. He was a European but he was working
simplex. I bet there was an OO sitting there sending notices to every US
contact he made.

If you KNOW your frequency to 1 Hz, you can legally operate with your dial
on 14149.9 and still be in the band. Likewise 7300.1. Also RTTY on 3601,
etc. etc. A super accurate transmitter has it's advantages :-)

Jerry - K0TV

----- Original Message -----
From: "Matt Zilmer" <[hidden email]>
To: "Rick Stealey" <[hidden email]>
Cc: <[hidden email]>
Sent: Sunday, March 20, 2011 6:48 PM
Subject: Re: [Elecraft] Installed K3EXREF

> The K3EXREF is in field test now, as far as I know. It might be a
> little while before Elecraft puts it up for sale.
>
> "Extreme accuracy" probably has two psychological and one scientific
> source:
> - The need to put the K3 dead-on frequency is reassuring to folks that
> aren't sure it stays that way mostly as-is with the TCXO.
> - The desire to be a frequency authority, and be able to help others
> when they're off-freq. Hams with older rigs sometimes end up shifted
> off freq. On HF, I hear this a lot.
> - Knowing exactly what frequency you're on helps with band-edge
> issues, for example between the Extra-only CW sub-bands and the
> general CW sub-band. With a 1 Hz readout, this is seldom a problem,
> but it gets even better when the last digit also indicates the actual
> carrier freq.
>
> The K3 with just the stock TCXO holds the reference at somewhere below
> 1 PPM anyway. This is probably accurate enough for almost everyone,
> but some want near-perfect accuracy. GPS time has an uncertainty of
> around 0.3 nS, which is pretty low compared to 1PPM. No TCXO can beat
> that, but maybe an OCXO can?
>
> 73,
> matt W6NIA
>
>
>
> On Sun, 20 Mar 2011 14:45:59 +0000, you wrote:
>
>>
>>
>>Excellent posting by W9AC, a great reference, to be saved.
>>Now I wonder if it would be possible for someone to enlighten me as to
>>the need for such extreme accuracy? Is it because my K3 reads out to 1 Hz
>>but I can't really believe the absolute accuracy of that number unless I
>>get a K3EXREF? But if that is the case, my question would still remain,
>>wouldn't it?
>>Not that I need something else to put on my list ahead of my P3 and
>>sub receiver.
>>Rick K2XT
>>
>>______________________________________________________________
>>Elecraft mailing list
>>Home: http://mailman.qth.net/mailman/listinfo/elecraft
>>Help: http://mailman.qth.net/mmfaq.htm
>>Post: mailto:[hidden email]
>>
>>This list hosted by: http://www.qsl.net
>>Please help support this email list: http://www.qsl.net/donate.html
> ______________________________________________________________
> Elecraft mailing list
> Home: http://mailman.qth.net/mailman/listinfo/elecraft
> Help: http://mailman.qth.net/mmfaq.htm
> Post: mailto:[hidden email]
>
> This list hosted by: http://www.qsl.net
> Please help support this email list: http://www.qsl.net/donate.html

Don Wilhelm-4

Re: Installed K3EXREF

Jerry,

RE: 14149.9 kHz ---
I would not be comfortable cutting it that close in USB unless I was
absolutely certain there was absolutely no energy in the SSB audio 0 to
100 Hz range. I would not trust any transmitter (no matter how good) in
that regard. Keep it all within the band limits to be safe.

73,
Don W3FPR

On 3/20/2011 9:12 PM, Jerry Muller wrote:

Matt Zilmer

Re: Installed K3EXREF

In reply to this post by Jerry Muller

Most of the applications where "extreme accuracy" is really needed are
transverters at microwave freqs. That is a lot of the feedback
received here. I believe that. It makes the most sense.

A couple of PPM is plenty good for HF, imho. But there are those of
us that have the frequency fetish. See the FMT for example. Dunno
how many OO's have the capability to measure overall output to within
a few Hz, nor how many can measure amplitudes to required levels of
suppression. There must be some, and some are K3 owners.

I got cited once, in 1973 by the FCC monitoring station in Kingsville,
TX, when my dial marker was off by about 1 KHz. With the K3, nothing
like that is a worry. But the K3EXREF makes it a certainty that you
will have no excuse....

73,
matt W6NIA
K3 #24

On Sun, 20 Mar 2011 21:12:19 -0400, you wrote:

>Speaking of band edges....
>
>During the recent ARRL DX SSB contest, there was a station operating on
>7127. Because of the lower SB extending to 7124 (assuming 3k bandwidth) he
>was operating out of the US phone band. He was a European but he was working
>simplex. I bet there was an OO sitting there sending notices to every US
>contact he made.
>
>If you KNOW your frequency to 1 Hz, you can legally operate with your dial
>on 14149.9 and still be in the band. Likewise 7300.1. Also RTTY on 3601,
>etc. etc. A super accurate transmitter has it's advantages :-)
>
>Jerry - K0TV
>
>----- Original Message -----
>From: "Matt Zilmer" <[hidden email]>
>To: "Rick Stealey" <[hidden email]>
>Cc: <[hidden email]>
>Sent: Sunday, March 20, 2011 6:48 PM
>Subject: Re: [Elecraft] Installed K3EXREF
>
>
>> The K3EXREF is in field test now, as far as I know. It might be a
>> little while before Elecraft puts it up for sale.
>>
>> "Extreme accuracy" probably has two psychological and one scientific
>> source:
>> - The need to put the K3 dead-on frequency is reassuring to folks that
>> aren't sure it stays that way mostly as-is with the TCXO.
>> - The desire to be a frequency authority, and be able to help others
>> when they're off-freq. Hams with older rigs sometimes end up shifted
>> off freq. On HF, I hear this a lot.
>> - Knowing exactly what frequency you're on helps with band-edge
>> issues, for example between the Extra-only CW sub-bands and the
>> general CW sub-band. With a 1 Hz readout, this is seldom a problem,
>> but it gets even better when the last digit also indicates the actual
>> carrier freq.
>>
>> The K3 with just the stock TCXO holds the reference at somewhere below
>> 1 PPM anyway. This is probably accurate enough for almost everyone,
>> but some want near-perfect accuracy. GPS time has an uncertainty of
>> around 0.3 nS, which is pretty low compared to 1PPM. No TCXO can beat
>> that, but maybe an OCXO can?
>>
>> 73,
>> matt W6NIA
>>
>>
>>
>> On Sun, 20 Mar 2011 14:45:59 +0000, you wrote:
>>
>>>
>>>
>>>Excellent posting by W9AC, a great reference, to be saved.
>>>Now I wonder if it would be possible for someone to enlighten me as to
>>>the need for such extreme accuracy? Is it because my K3 reads out to 1 Hz
>>>but I can't really believe the absolute accuracy of that number unless I
>>>get a K3EXREF? But if that is the case, my question would still remain,
>>>wouldn't it?
>>>Not that I need something else to put on my list ahead of my P3 and
>>>sub receiver.
>>>Rick K2XT
>>>
>>>______________________________________________________________
>>>Elecraft mailing list
>>>Home: http://mailman.qth.net/mailman/listinfo/elecraft
>>>Help: http://mailman.qth.net/mmfaq.htm
>>>Post: mailto:[hidden email]
>>>
>>>This list hosted by: http://www.qsl.net
>>>Please help support this email list: http://www.qsl.net/donate.html
>> ______________________________________________________________
>> Elecraft mailing list
>> Home: http://mailman.qth.net/mailman/listinfo/elecraft
>> Help: http://mailman.qth.net/mmfaq.htm
>> Post: mailto:[hidden email]
>>
>> This list hosted by: http://www.qsl.net
>> Please help support this email list: http://www.qsl.net/donate.html
>
>
>______________________________________________________________
>Elecraft mailing list
>Home: http://mailman.qth.net/mailman/listinfo/elecraft
>Help: http://mailman.qth.net/mmfaq.htm
>Post: mailto:[hidden email]
>
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>Please help support this email list: http://www.qsl.net/donate.html

George Dubovsky

Re: Installed K3EXREF

In reply to this post by Jerry Muller

List,

I know a thing or three about those Trimble T'bolts; I am a design engineer
for the company that made the (previous generation) equipment that is now
being surplussed in several parts of the world. There is no domestic or
Chinese thunderbolt; there is the commercial version (silver and red case
with internal dc-dc converter - runs off of 24 VDC) and the OEM version
(thin gold case, sometimes with the original 3 dB splitter still attached to
the case, no power supply). The OEM version being surplussed contains the
same GPSDO guts as the commercial version, with two exceptions: the power
connector is on the opposite side of the pwb, and one Zener diode is changed
to move the trip point for the DC Power alarm to a lower value. Also, the
newer units have a later date code Dallas Semi temp sensor that does not
report temperature in the finer steps of the earlier date codes - this is
not an issue for most folks.

The OEM units require +5 , +12, and -7 to -12 VDC at modest current
requirements. It is easy to find a surplus power supply that supports these
units and it is just as easy to roll your own. I usually have a few tested
OEM units available for sale, with or without the gold case (if you want to
build it into your own cabinet).

In addition, if you want the ultimate K3 accessory, I have a NIB Symmetricom
Starloc II Plus, GPS-disciplined Rubidium oscillator for sale.

Let me know if you want to know anything else about the Thunderbolt, or if
you want one of your own.

73,

geo - n4ua

On Sun, Mar 20, 2011 at 9:05 PM, Jerry Muller <[hidden email]> wrote:

> This was an excellent explanation.
>
> I got a Trimble Thunderbolt off eBay for less than 200 bucks. It came from
> China and came with an antenna and power supply. If you are going to get
> one
> of the ones that come from China, make sure you get the power supply with
> it. The domestic Thunderbolts have a unipolar supply but the ones from
> China
> were specials and require a special bipolar power supply. As long as you're
> getting the power supply with it, you're OK. I have not noticed any noise
> from the power supply from China. I expect ferrites may solve the problem
> if
> found.
>
> It works just fine with the stock Thunderbolt software. I've had mine for
> about 6 months and I've run tests using the Thunderbolt software. The PC
> monitoring software allows you to monitor the errors detected and log them.
> The accuracy is quite good. Although I see occasional errors greater than 1
> part in 10^9, most of the measured errors are far less than 1 part in 10^9.
> I can't find any of the spreadsheets I generated (from many hours of
> operation) right now but I seem to recall that 1 sigma was down around 1
> part in 10^10. This translates into a 1 Hz error at 10 GHz. The +/- 1 Hz
> error in the K3 is much greater than the accuracy of the GPSDO
>
> My primary reason for getting the GPSDO was for microwave and EME
> operations. Being able to use it with the K3 is a plus. I'm likely to be an
> early adopter of the production units when they become available. I will
> probably order my second K3 with a K3EXREF.
>
> Jerry - K0TV
>
> ----- Original Message -----
> From: "Paul Christensen" <[hidden email]>
> To: <[hidden email]>
> Sent: Saturday, March 19, 2011 9:34 PM
> Subject: Re: [Elecraft] Installed K3EXREF
>
>
> >I installed it on Friday in about 30 minutes, but I'm comfortable with my
> > way around the K3. I would think that most users could install it in
> > about
> > an hour or less. Installation is actually very simple with very few
> parts
> > involved. K3EXREF came with an SMA connector and SMA to BNC
> > between-series
> > adapter.
> >
> > Performance is exactly as promised by Elecraft. Although K3EXREF will
> not
> > phase lock the K3 to the external frequency source, I'm finding that it
> > stays within 1 Hz on 20m when locked to CHU at 14.670 MHz. I'm also
> > finding that testing for zero-beat to WWV at 10 MHz is not a good idea in
> > my
> > shack, and perhaps yours too. There are many 10 MHz signals being
> emitted
> > by nearby appliances, LAN routers, security system, Ethernet boards, etc.
> > That common, even frequency is everywhere in a household these days.
> >
> > In much of North America, CHU is an excellent source for testing since it
> > keeps cesium accuracy like WWV but the odd frequency of CHU is a real
> > benefit since the chance for beating against extraneous signals is much
> > smaller than at 10 MHz. Testing at a higher frequency rather than say
> the
> > MW broadcast band also provides for a reasonably good account of how the
> > K3EXREF performs. After installation, I would also suggest not trying
> to
> > test zero beat K3EXREF against commercial MW or SW BC stations since
> their
> > carriers are allowed to deviate much more than the cesium-based time and
> > frequency standards of CHU and WWV. Commercial AM broadcast station
> > frequencies are typically only accurate to about +/- 20 Hz although most
> > are
> > better than that.
> >
> > The K3's 49 MHz oscillator is only adjusted at intervals between 4 and 8
> > seconds by K3EXREF in order to minimize jitter. The K3 retains its
> > original
> > phase noise performance since the external reference is not used internal
> > to
> > the K3's frequency generating scheme. Think of it this way -- K3EXREF is
> > like lightly touching the 49 MHz oscillator with a feather every few
> > seconds
> > if necessary to keep it within 1 Hz or so. Also, the K3 frequency stays
> > accurate even at the moment of powering up the K3. Kinda' fun to watch
> > the
> > 49 MHz oscillator display change during warm-up as it's being corrected
> > and
> > compared against the external reference.
> >
> > External references: There are three primary types, and all can be
> > purchased for less than USD $150 on the used market. Cesium standards (a
> > fourth type) are also available but are generally much more expensive,
> > complicated, and won't offer any benefit to K3 users since K3EXREF limits
> > resolution and accuracy to about 1 Hz.
> >
> > The first type is the GPS Disciplined Oscillator (GPS-DO). This type of
> > standard locks itself onto the visible GPS satellites orbiting the sky.
> > Requires a GPS antenna and is self-calibrating to the GPS satellites.
> The
> > GPS-DO's time and frequency averages from the visible satellites, each
> > satellite having it's own on-board cesium-based oscillator. Long-term
> > accuracy is usually good to at least 1 x 10^-11. Extreme accuracy and
> > only
> > a magnitude or two behind cesium. Look for Hewlett-Packard Z3801A,
> > Z3816A,
> > Trimble Thunderbolt, Brandywine, Symmetricon, and Datum models. Short
> > list,
> > but many others available.
> >
> > Rubidium is the next type. No GPS tracking needed. Accuracy
> commensurate
> > with GPS-DO. No antenna required. Long-term performance is highly
> > dependent on the quality of the optical beam from the rubidium pump lamp.
> > Look for EF Efratom, Datum,
> >
> > Third, is a high quality oven-controlled crystal oscillator (OCXO).
> > Requires periodic calibration. Accuracy good to at least +/- 0.05 ppm
> and
> > offer the best phase noise performance among the three types of
> > oscillators,
> > but as noted earlier, the excellent phase noise attributes of the OCXO
> > will
> > not be carried over to the K3.
> >
> > A shack reference oscillator is good for use with other equipment too
> > (e.g.,
> > frequency counter). Although a bit lossy, I currectly use a
> > Mini-Circuits
> > passive three-way splitter, but one can purchase a distribution amp to
> > feed
> > many pieces of equipment from a single oscillator. Unlike the splitter,
> a
> > DA offers unity gain and very high port isolation.
> >
> > Finally, be mindful that most GPS-DO and rubidium units use internal
> > switch-mode DC-DC converters. Switching noise was bad enough on two of
> my
> > units that I decided to gut the converters and used an outboard
> > triple-output linear supply. The Trimble Thunderbolts that have been
> > retired from the cellular industry require an external triple-output
> > supply.
> > If choosing this model, get a linear type and avoid the headaches.
> >
> > Paul, W9AC
> >
> > ______________________________________________________________
> > Elecraft mailing list
> > Home: http://mailman.qth.net/mailman/listinfo/elecraft
> > Help: http://mailman.qth.net/mmfaq.htm
> > Post: mailto:[hidden email]
> >
> > This list hosted by: http://www.qsl.net
> > Please help support this email list: http://www.qsl.net/donate.html
>
>
> ______________________________________________________________
> Elecraft mailing list
> Home: http://mailman.qth.net/mailman/listinfo/elecraft
> Help: http://mailman.qth.net/mmfaq.htm
> Post: mailto:[hidden email]
>
> This list hosted by: http://www.qsl.net
> Please help support this email list: http://www.qsl.net/donate.html
>

Tom Azlin N4ZPT

Re: Installed K3EXREF

In reply to this post by Jim AB3CV

And EME at 23cm given the rest of my station can be linked to my G3RUH
GPS stabilized 10MHz ref.

73, tom n4zpt

On 3/20/2011 11:51 AM, Jim Miller wrote:

> I'm guessing this is really useful for EME at UHF.
>
> jim ab3cv
> ______________________________________________________________
> Elecraft mailing list
> Home: http://mailman.qth.net/mailman/listinfo/elecraft
> Help: http://mailman.qth.net/mmfaq.htm
> Post: mailto:[hidden email]
>
> This list hosted by: http://www.qsl.net
> Please help support this email list: http://www.qsl.net/donate.html
>

w4ish

Re: Installed K3EXREF

In reply to this post by George Dubovsky

GEORGE,

So they include the antenna, and what would the cost be for one without the gold case?

W4ISH

Bill

On Mar 21, 2011, at 8:50 AM, George Dubovsky [via Elecraft] wrote:

> This was an excellent explanation.
>
> I got a Trimble Thunderbolt off eBay for less than 200 bucks. It came from
> China and came with an antenna and power supply. If you are going to get
> one
> of the ones that come from China, make sure you get the power supply with
> it. The domestic Thunderbolts have a unipolar supply but the ones from
> China
> were specials and require a special bipolar power supply. As long as you're
> getting the power supply with it, you're OK. I have not noticed any noise
> from the power supply from China. I expect ferrites may solve the problem
> if
> found.
>
> It works just fine with the stock Thunderbolt software. I've had mine for
> about 6 months and I've run tests using the Thunderbolt software. The PC
> monitoring software allows you to monitor the errors detected and log them.
> The accuracy is quite good. Although I see occasional errors greater than 1
> part in 10^9, most of the measured errors are far less than 1 part in 10^9.
> I can't find any of the spreadsheets I generated (from many hours of
> operation) right now but I seem to recall that 1 sigma was down around 1
> part in 10^10. This translates into a 1 Hz error at 10 GHz. The +/- 1 Hz
> error in the K3 is much greater than the accuracy of the GPSDO
>
> My primary reason for getting the GPSDO was for microwave and EME
> operations. Being able to use it with the K3 is a plus. I'm likely to be an
> early adopter of the production units when they become available. I will
> probably order my second K3 with a K3EXREF.
>
> Jerry - K0TV
>
> ----- Original Message -----
> From: "Paul Christensen" <<a href="x-msg://39/user/SendEmail.jtp?type=node&node=6192128&i=1&by-user=t" target="_top" rel="nofollow" link="external">[hidden email]>
> To: <<a href="x-msg://39/user/SendEmail.jtp?type=node&node=6192128&i=2&by-user=t" target="_top" rel="nofollow" link="external">[hidden email]>
> Sent: Saturday, March 19, 2011 9:34 PM
> Subject: Re: [Elecraft] Installed K3EXREF
>
>
> >I installed it on Friday in about 30 minutes, but I'm comfortable with my
> > way around the K3. I would think that most users could install it in
> > about
> > an hour or less. Installation is actually very simple with very few
> parts
> > involved. K3EXREF came with an SMA connector and SMA to BNC
> > between-series
> > adapter.
> >
> > Performance is exactly as promised by Elecraft. Although K3EXREF will
> not
> > phase lock the K3 to the external frequency source, I'm finding that it
> > stays within 1 Hz on 20m when locked to CHU at 14.670 MHz. I'm also
> > finding that testing for zero-beat to WWV at 10 MHz is not a good idea in
> > my
> > shack, and perhaps yours too. There are many 10 MHz signals being
> emitted
> > by nearby appliances, LAN routers, security system, Ethernet boards, etc.
> > That common, even frequency is everywhere in a household these days.
> >
> > In much of North America, CHU is an excellent source for testing since it
> > keeps cesium accuracy like WWV but the odd frequency of CHU is a real
> > benefit since the chance for beating against extraneous signals is much
> > smaller than at 10 MHz. Testing at a higher frequency rather than say
> the
> > MW broadcast band also provides for a reasonably good account of how the
> > K3EXREF performs. After installation, I would also suggest not trying
> to
> > test zero beat K3EXREF against commercial MW or SW BC stations since
> their
> > carriers are allowed to deviate much more than the cesium-based time and
> > frequency standards of CHU and WWV. Commercial AM broadcast station
> > frequencies are typically only accurate to about +/- 20 Hz although most
> > are
> > better than that.
> >
> > The K3's 49 MHz oscillator is only adjusted at intervals between 4 and 8
> > seconds by K3EXREF in order to minimize jitter. The K3 retains its
> > original
> > phase noise performance since the external reference is not used internal
> > to
> > the K3's frequency generating scheme. Think of it this way -- K3EXREF is
> > like lightly touching the 49 MHz oscillator with a feather every few
> > seconds
> > if necessary to keep it within 1 Hz or so. Also, the K3 frequency stays
> > accurate even at the moment of powering up the K3. Kinda' fun to watch
> > the
> > 49 MHz oscillator display change during warm-up as it's being corrected
> > and
> > compared against the external reference.
> >
> > External references: There are three primary types, and all can be
> > purchased for less than USD $150 on the used market. Cesium standards (a
> > fourth type) are also available but are generally much more expensive,
> > complicated, and won't offer any benefit to K3 users since K3EXREF limits
> > resolution and accuracy to about 1 Hz.
> >
> > The first type is the GPS Disciplined Oscillator (GPS-DO). This type of
> > standard locks itself onto the visible GPS satellites orbiting the sky.
> > Requires a GPS antenna and is self-calibrating to the GPS satellites.
> The
> > GPS-DO's time and frequency averages from the visible satellites, each
> > satellite having it's own on-board cesium-based oscillator. Long-term
> > accuracy is usually good to at least 1 x 10^-11. Extreme accuracy and
> > only
> > a magnitude or two behind cesium. Look for Hewlett-Packard Z3801A,
> > Z3816A,
> > Trimble Thunderbolt, Brandywine, Symmetricon, and Datum models. Short
> > list,
> > but many others available.
> >
> > Rubidium is the next type. No GPS tracking needed. Accuracy
> commensurate
> > with GPS-DO. No antenna required. Long-term performance is highly
> > dependent on the quality of the optical beam from the rubidium pump lamp.
> > Look for EF Efratom, Datum,
> >
> > Third, is a high quality oven-controlled crystal oscillator (OCXO).
> > Requires periodic calibration. Accuracy good to at least +/- 0.05 ppm
> and
> > offer the best phase noise performance among the three types of
> > oscillators,
> > but as noted earlier, the excellent phase noise attributes of the OCXO
> > will
> > not be carried over to the K3.
> >
> > A shack reference oscillator is good for use with other equipment too
> > (e.g.,
> > frequency counter). Although a bit lossy, I currectly use a
> > Mini-Circuits
> > passive three-way splitter, but one can purchase a distribution amp to
> > feed
> > many pieces of equipment from a single oscillator. Unlike the splitter,
> a
> > DA offers unity gain and very high port isolation.
> >
> > Finally, be mindful that most GPS-DO and rubidium units use internal
> > switch-mode DC-DC converters. Switching noise was bad enough on two of
> my
> > units that I decided to gut the converters and used an outboard
> > triple-output linear supply. The Trimble Thunderbolts that have been
> > retired from the cellular industry require an external triple-output
> > supply.
> > If choosing this model, get a linear type and avoid the headaches.
> >
> > Paul, W9AC
> >
> > ______________________________________________________________
> > Elecraft mailing list
> > Home: http://mailman.qth.net/mailman/listinfo/elecraft
> > Help: http://mailman.qth.net/mmfaq.htm
> > Post: mailto:<a href="x-msg://39/user/SendEmail.jtp?type=node&node=6192128&i=3&by-user=t" target="_top" rel="nofollow" link="external">[hidden email]
> >
> > This list hosted by: http://www.qsl.net
> > Please help support this email list: http://www.qsl.net/donate.html
>
>
> ______________________________________________________________
> Elecraft mailing list
> Home: http://mailman.qth.net/mailman/listinfo/elecraft
> Help: http://mailman.qth.net/mmfaq.htm
> Post: mailto:<a href="x-msg://39/user/SendEmail.jtp?type=node&node=6192128&i=4&by-user=t" target="_top" rel="nofollow" link="external">[hidden email]
>
> This list hosted by: http://www.qsl.net
> Please help support this email list: http://www.qsl.net/donate.html
>

______________________________________________________________

Elecraft mailing list
Home: http://mailman.qth.net/mailman/listinfo/elecraft
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n7ws

Re: Installed K3EXREF

In reply to this post by P.B. Christensen

I'm not picking on Paul, this is just a handy place to reply. I'm going to say this one more time (the first time was two years ago).

I really don't understand all of the fuss about 1 Hz accuracy when just changing the K3 Width and Shift controls moves the frequency more than that and this is band dependent.

On ten-meters I can listen to a crystal-controlled source and hear the beat note change as Shift and Width are adjusted.

Elecraft considers its frequency conversion scheme to be proprietary but it's obvious that not all of the oscillators are moving at the same rate.

Wes N7WS

--- On Sat, 3/19/11, Paul Christensen <[hidden email]> wrote:

> I installed it on Friday in about 30
> minutes, but I'm comfortable with my
> way around the K3. I would think that most users
> could install it in about
> an hour or less. Installation is actually very simple
> with very few parts
> involved. K3EXREF came with an SMA connector and SMA
> to BNC between-series
> adapter.
>
> Performance is exactly as promised by Elecraft.
> Although K3EXREF will not
> phase lock the K3 to the external frequency source, I'm
> finding that it
> stays within 1 Hz on 20m when locked to CHU at 14.670
> MHz.   I'm also
> finding that testing for zero-beat to WWV at 10 MHz is not
> a good idea in my
> shack, and perhaps yours too. There are many 10 MHz
> signals being emitted
> by nearby appliances, LAN routers, security system,
> Ethernet boards, etc.
> That common, even frequency is everywhere in a household
> these days.
>
> In much of North America, CHU is an excellent source for
> testing since it
> keeps cesium accuracy like WWV but the odd frequency of CHU
> is a real
> benefit since the chance for beating against extraneous
> signals is much
> smaller than at 10 MHz. Testing at a higher frequency
> rather than say the
> MW broadcast band also provides for a reasonably good
> account of how the
> K3EXREF performs.   After installation, I
> would also suggest not trying to
> test zero beat K3EXREF against commercial MW or SW BC
> stations since their
> carriers are allowed to deviate much more than the
> cesium-based time and
> frequency standards of CHU and WWV. Commercial AM
> broadcast station
> frequencies are typically only accurate to about +/- 20 Hz
> although most are
> better than that.
>
> The K3's 49 MHz oscillator is only adjusted at intervals
> between 4 and 8
> seconds by K3EXREF in order to minimize jitter. The
> K3 retains its original
> phase noise performance since the external reference is not
> used internal to
> the K3's frequency generating scheme. Think of it
> this way -- K3EXREF is
> like lightly touching the 49 MHz oscillator with a feather
> every few seconds
> if necessary to keep it within 1 Hz or so. Also, the
> K3 frequency stays
> accurate even at the moment of powering up the K3.
> Kinda' fun to watch the
> 49 MHz oscillator display change during warm-up as it's
> being corrected and
> compared against the external reference.
>
> External references: There are three primary types,
> and all can be
> purchased for less than USD $150 on the used market.
> Cesium standards (a
> fourth type) are also available but are generally much more
> expensive,
> complicated, and won't offer any benefit to K3 users since
> K3EXREF limits
> resolution and accuracy to about 1 Hz.
>
> The first type is the GPS Disciplined Oscillator
> (GPS-DO).   This type of
> standard locks itself onto the visible GPS satellites
> orbiting the sky.
> Requires a GPS antenna and is self-calibrating to the GPS
> satellites. The
> GPS-DO's time and frequency averages from the visible
> satellites, each
> satellite having it's own on-board cesium-based
> oscillator. Long-term
> accuracy is usually good to at least 1 x 10^-11.
> Extreme accuracy and only
> a magnitude or two behind cesium. Look for
> Hewlett-Packard Z3801A, Z3816A,
> Trimble Thunderbolt, Brandywine, Symmetricon, and Datum
> models. Short list,
> but many others available.
>
> Rubidium is the next type. No GPS tracking
> needed. Accuracy commensurate
> with GPS-DO. No antenna required. Long-term
> performance is highly
> dependent on the quality of the optical beam from the
> rubidium pump lamp.
> Look for EF Efratom, Datum,
>
> Third, is a high quality oven-controlled crystal oscillator
> (OCXO).
> Requires periodic calibration. Accuracy good to at
> least +/- 0.05 ppm and
> offer the best phase noise performance among the three
> types of oscillators,
> but as noted earlier, the excellent phase noise attributes
> of the OCXO will
> not be carried over to the K3.
>
> A shack reference oscillator is good for use with other
> equipment too (e.g.,
> frequency counter).   Although a bit lossy,
> I currectly use a Mini-Circuits
> passive three-way splitter, but one can purchase a
> distribution amp to feed
> many pieces of equipment from a single oscillator.
> Unlike the splitter, a
> DA offers unity gain and very high port isolation.
>
> Finally, be mindful that most GPS-DO and rubidium units use
> internal
> switch-mode DC-DC converters. Switching noise was bad
> enough on two of my
> units that I decided to gut the converters and used an
> outboard
> triple-output linear supply. The Trimble Thunderbolts
> that have been
> retired from the cellular industry require an external
> triple-output supply.
> If choosing this model, get a linear type and avoid the
> headaches.
>
> Paul, W9AC
>

wayne burdick

Re: Installed K3EXREF

Administrator

Wes Stewart wrote:

> I really don't understand all of the fuss about 1 Hz accuracy....

Because so many customers asked for it. I'll leave it to them to list
their reasons, but in my case, I like being dead-on over a wide range
of temperatures without having to occasionally recheck my manual REF
CAL setting using a beat note with WWV.

> when just changing the K3 Width and Shift controls moves the
> frequency more than that....

SHIFT and WIDTH move the I.F. by an accurate amount, and should not
introduce any error in the operating frequency beyond that of normal
DDS granularity, which can be +/- 1 Hz or so depending on the band.

> On ten-meters I can listen to a crystal-controlled source and hear
> the beat note change as Shift and Width are adjusted.

That is due to DDS granularity. There is no such error where phase
coherency really counts--in diversity mode. In that case the two
synthesizers are always phase-locked as long as the crystal filter
offsets are matched.

> Elecraft considers its frequency conversion scheme to be proprietary
> but it's obvious that not all of the oscillators are moving at the
> same rate.

They are all subject to our DDS step size of aprox. 1/5th Hz. In
diversity mode the DDS words are identical, but in other cases the two
synths can be off by this amount in either direction, resulting in a
small tuning error that is proportional to operating frequency. It
amounts to about +/- 1 Hz.

73,
Wayne

______________________________________________________________
Elecraft mailing list
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Help: http://mailman.qth.net/mmfaq.htm
Post: mailto:[hidden email]

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N5GE

Re: Installed K3EXREF

In reply to this post by n7ws

Glad you're going to give it a rest.....

N5GE

On Fri, 25 Mar 2011 09:45:31 -0700 (PDT), Wes Stewart <[hidden email]> wrote:

>I'm not picking on Paul, this is just a handy place to reply. I'm going to say this one more time (the first time was two years ago).
>
>I really don't understand all of the fuss about 1 Hz accuracy when just changing the K3 Width and Shift controls moves the frequency more than that and this is band dependent.
>
>On ten-meters I can listen to a crystal-controlled source and hear the beat note change as Shift and Width are adjusted.
>
>Elecraft considers its frequency conversion scheme to be proprietary but it's obvious that not all of the oscillators are moving at the same rate.
>
>Wes N7WS
>
>--- On Sat, 3/19/11, Paul Christensen <[hidden email]> wrote:
>
>> I installed it on Friday in about 30
>> minutes, but I'm comfortable with my
>> way around the K3. I would think that most users
>> could install it in about
>> an hour or less. Installation is actually very simple
>> with very few parts
>> involved. K3EXREF came with an SMA connector and SMA
>> to BNC between-series
>> adapter.
>>
>> Performance is exactly as promised by Elecraft.
>> Although K3EXREF will not
>> phase lock the K3 to the external frequency source, I'm
>> finding that it
>> stays within 1 Hz on 20m when locked to CHU at 14.670
>> MHz.   I'm also
>> finding that testing for zero-beat to WWV at 10 MHz is not
>> a good idea in my
>> shack, and perhaps yours too. There are many 10 MHz
>> signals being emitted
>> by nearby appliances, LAN routers, security system,
>> Ethernet boards, etc.
>> That common, even frequency is everywhere in a household
>> these days.
>>
>> In much of North America, CHU is an excellent source for
>> testing since it
>> keeps cesium accuracy like WWV but the odd frequency of CHU
>> is a real
>> benefit since the chance for beating against extraneous
>> signals is much
>> smaller than at 10 MHz. Testing at a higher frequency
>> rather than say the
>> MW broadcast band also provides for a reasonably good
>> account of how the
>> K3EXREF performs.   After installation, I
>> would also suggest not trying to
>> test zero beat K3EXREF against commercial MW or SW BC
>> stations since their
>> carriers are allowed to deviate much more than the
>> cesium-based time and
>> frequency standards of CHU and WWV. Commercial AM
>> broadcast station
>> frequencies are typically only accurate to about +/- 20 Hz
>> although most are
>> better than that.
>>
>> The K3's 49 MHz oscillator is only adjusted at intervals
>> between 4 and 8
>> seconds by K3EXREF in order to minimize jitter. The
>> K3 retains its original
>> phase noise performance since the external reference is not
>> used internal to
>> the K3's frequency generating scheme. Think of it
>> this way -- K3EXREF is
>> like lightly touching the 49 MHz oscillator with a feather
>> every few seconds
>> if necessary to keep it within 1 Hz or so. Also, the
>> K3 frequency stays
>> accurate even at the moment of powering up the K3.
>> Kinda' fun to watch the
>> 49 MHz oscillator display change during warm-up as it's
>> being corrected and
>> compared against the external reference.
>>
>> External references: There are three primary types,
>> and all can be
>> purchased for less than USD $150 on the used market.
>> Cesium standards (a
>> fourth type) are also available but are generally much more
>> expensive,
>> complicated, and won't offer any benefit to K3 users since
>> K3EXREF limits
>> resolution and accuracy to about 1 Hz.
>>
>> The first type is the GPS Disciplined Oscillator
>> (GPS-DO).   This type of
>> standard locks itself onto the visible GPS satellites
>> orbiting the sky.
>> Requires a GPS antenna and is self-calibrating to the GPS
>> satellites. The
>> GPS-DO's time and frequency averages from the visible
>> satellites, each
>> satellite having it's own on-board cesium-based
>> oscillator. Long-term
>> accuracy is usually good to at least 1 x 10^-11.
>> Extreme accuracy and only
>> a magnitude or two behind cesium. Look for
>> Hewlett-Packard Z3801A, Z3816A,
>> Trimble Thunderbolt, Brandywine, Symmetricon, and Datum
>> models. Short list,
>> but many others available.
>>
>> Rubidium is the next type. No GPS tracking
>> needed. Accuracy commensurate
>> with GPS-DO. No antenna required. Long-term
>> performance is highly
>> dependent on the quality of the optical beam from the
>> rubidium pump lamp.
>> Look for EF Efratom, Datum,
>>
>> Third, is a high quality oven-controlled crystal oscillator
>> (OCXO).
>> Requires periodic calibration. Accuracy good to at
>> least +/- 0.05 ppm and
>> offer the best phase noise performance among the three
>> types of oscillators,
>> but as noted earlier, the excellent phase noise attributes
>> of the OCXO will
>> not be carried over to the K3.
>>
>> A shack reference oscillator is good for use with other
>> equipment too (e.g.,
>> frequency counter).   Although a bit lossy,
>> I currectly use a Mini-Circuits
>> passive three-way splitter, but one can purchase a
>> distribution amp to feed
>> many pieces of equipment from a single oscillator.
>> Unlike the splitter, a
>> DA offers unity gain and very high port isolation.
>>
>> Finally, be mindful that most GPS-DO and rubidium units use
>> internal
>> switch-mode DC-DC converters. Switching noise was bad
>> enough on two of my
>> units that I decided to gut the converters and used an
>> outboard
>> triple-output linear supply. The Trimble Thunderbolts
>> that have been
>> retired from the cellular industry require an external
>> triple-output supply.
>> If choosing this model, get a linear type and avoid the
>> headaches.
>>
>> Paul, W9AC
>>
>______________________________________________________________
>Elecraft mailing list
>Home: http://mailman.qth.net/mailman/listinfo/elecraft
>Help: http://mailman.qth.net/mmfaq.htm
>Post: mailto:[hidden email]
>
>This list hosted by: http://www.qsl.net
>Please help support this email list: http://www.qsl.net/donate.html

Amateur Radio Operator N5GE

n7ws

Re: Installed K3EXREF

You should try it.

--- On Fri, 3/25/11, [hidden email] <[hidden email]> wrote:

> From: [hidden email] <[hidden email]>
> Subject: Re: [Elecraft] Installed K3EXREF
> To: [hidden email]
> Date: Friday, March 25, 2011, 1:02 PM
>
> Glad you're going to give it a rest.....
>
> N5GE
>
> On Fri, 25 Mar 2011 09:45:31 -0700 (PDT), Wes Stewart
> <[hidden email]>
> wrote:
>
> >I'm not picking on Paul, this is just a handy place to
> reply. I'm going to say this one more time (the first time
> was two years ago).
> >
> >I really don't understand all of the fuss about 1 Hz
> accuracy when just changing the K3 Width and Shift controls
> moves the frequency more than that and this is band
> dependent.
> >
> >On ten-meters I can listen to a crystal-controlled
> source and hear the beat note change as Shift and Width are
> adjusted.
> >
> >Elecraft considers its frequency conversion scheme to
> be proprietary but it's obvious that not all of the
> oscillators are moving at the same rate.
> >
> >Wes N7WS
> >
> >--- On Sat, 3/19/11, Paul Christensen <[hidden email]>
> wrote:
> >
> >> I installed it on Friday in about 30
> >> minutes, but I'm comfortable with my
> >> way around the K3. I would think that most
> users
> >> could install it in about
> >> an hour or less. Installation is actually very
> simple
> >> with very few parts
> >> involved. K3EXREF came with an SMA connector and
> SMA
> >> to BNC between-series
> >> adapter.
> >>
> >> Performance is exactly as promised by Elecraft.
> >> Although K3EXREF will not
> >> phase lock the K3 to the external frequency
> source, I'm
> >> finding that it
> >> stays within 1 Hz on 20m when locked to CHU at
> 14.670
> >> MHz.   I'm also
> >> finding that testing for zero-beat to WWV at 10
> MHz is not
> >> a good idea in my
> >> shack, and perhaps yours too. There are many 10
> MHz
> >> signals being emitted
> >> by nearby appliances, LAN routers, security
> system,
> >> Ethernet boards, etc.
> >> That common, even frequency is everywhere in a
> household
> >> these days.
> >>
> >> In much of North America, CHU is an excellent
> source for
> >> testing since it
> >> keeps cesium accuracy like WWV but the odd
> frequency of CHU
> >> is a real
> >> benefit since the chance for beating against
> extraneous
> >> signals is much
> >> smaller than at 10 MHz. Testing at a higher
> frequency
> >> rather than say the
> >> MW broadcast band also provides for a reasonably
> good
> >> account of how the
> >> K3EXREF performs.   After installation, I
> >> would also suggest not trying to
> >> test zero beat K3EXREF against commercial MW or SW
> BC
> >> stations since their
> >> carriers are allowed to deviate much more than
> the
> >> cesium-based time and
> >> frequency standards of CHU and WWV. Commercial
> AM
> >> broadcast station
> >> frequencies are typically only accurate to about
> +/- 20 Hz
> >> although most are
> >> better than that.
> >>
> >> The K3's 49 MHz oscillator is only adjusted at
> intervals
> >> between 4 and 8
> >> seconds by K3EXREF in order to minimize jitter.
> The
> >> K3 retains its original
> >> phase noise performance since the external
> reference is not
> >> used internal to
> >> the K3's frequency generating scheme. Think of
> it
> >> this way -- K3EXREF is
> >> like lightly touching the 49 MHz oscillator with a
> feather
> >> every few seconds
> >> if necessary to keep it within 1 Hz or so. Also,
> the
> >> K3 frequency stays
> >> accurate even at the moment of powering up the
> K3.
> >> Kinda' fun to watch the
> >> 49 MHz oscillator display change during warm-up as
> it's
> >> being corrected and
> >> compared against the external reference.
> >>
> >> External references: There are three primary
> types,
> >> and all can be
> >> purchased for less than USD $150 on the used
> market.
> >> Cesium standards (a
> >> fourth type) are also available but are generally
> much more
> >> expensive,
> >> complicated, and won't offer any benefit to K3
> users since
> >> K3EXREF limits
> >> resolution and accuracy to about 1 Hz.
> >>
> >> The first type is the GPS Disciplined Oscillator
> >> (GPS-DO).   This type of
> >> standard locks itself onto the visible GPS
> satellites
> >> orbiting the sky.
> >> Requires a GPS antenna and is self-calibrating to
> the GPS
> >> satellites. The
> >> GPS-DO's time and frequency averages from the
> visible
> >> satellites, each
> >> satellite having it's own on-board cesium-based
> >> oscillator. Long-term
> >> accuracy is usually good to at least 1 x
> 10^-11.
> >> Extreme accuracy and only
> >> a magnitude or two behind cesium. Look for
> >> Hewlett-Packard Z3801A, Z3816A,
> >> Trimble Thunderbolt, Brandywine, Symmetricon, and
> Datum
> >> models. Short list,
> >> but many others available.
> >>
> >> Rubidium is the next type. No GPS tracking
> >> needed. Accuracy commensurate
> >> with GPS-DO. No antenna required. Long-term
> >> performance is highly
> >> dependent on the quality of the optical beam from
> the
> >> rubidium pump lamp.
> >> Look for EF Efratom, Datum,
> >>
> >> Third, is a high quality oven-controlled crystal
> oscillator
> >> (OCXO).
> >> Requires periodic calibration. Accuracy good to
> at
> >> least +/- 0.05 ppm and
> >> offer the best phase noise performance among the
> three
> >> types of oscillators,
> >> but as noted earlier, the excellent phase noise
> attributes
> >> of the OCXO will
> >> not be carried over to the K3.
> >>
> >> A shack reference oscillator is good for use with
> other
> >> equipment too (e.g.,
> >> frequency counter).   Although a bit lossy,
> >> I currectly use a Mini-Circuits
> >> passive three-way splitter, but one can purchase
> a
> >> distribution amp to feed
> >> many pieces of equipment from a single
> oscillator.
> >> Unlike the splitter, a
> >> DA offers unity gain and very high port
> isolation.
> >>
> >> Finally, be mindful that most GPS-DO and rubidium
> units use
> >> internal
> >> switch-mode DC-DC converters. Switching noise
> was bad
> >> enough on two of my
> >> units that I decided to gut the converters and
> used an
> >> outboard
> >> triple-output linear supply. The Trimble
> Thunderbolts
> >> that have been
> >> retired from the cellular industry require an
> external
> >> triple-output supply.
> >> If choosing this model, get a linear type and
> avoid the
> >> headaches.
> >>
> >> Paul, W9AC
> >>
> >______________________________________________________________
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> >
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Dan AE9K

Re: Installed K3EXREF

In reply to this post by P.B. Christensen

This may be a naive question but...

If the K3EXREF keeps the K3's reference oscillator within 2 Hz, then what value is there in using the K3EXREF in conjunction with the KTCXO3 instead of just the native K3 oscillator?

K3EXREF: 2 Hz error @ 14 MHz : 0.1 ppm
K3TCXO3: 7 Hz error @ 14 MHz : 0.5 ppm

Is the stability in ppm an instantaneous measurement of random error and not a measurement potential drift over some time delta?

If this is true then using the K3EXREF alone presumably would exhibit the 5 ppm error of the native oscillator in the 4 to 8 second gaps between K3EXREF syncs. This would make the case for replacing the native oscillator with the K3TCXO3.

If the stability is measured over time, however, then the K3EXREF and native oscillator would appear to be sufficient since oscillator drift is insignificant in the 4 to 8 second time span.

Just curious.

Dan
AE9K

Edward R Cole

Re: Installed K3EXREF

In reply to this post by Edward R Cole

Dan,

The K3EXREF controls the TCXO-3 to maintain a near zero offset
compared with an external frequency reference. The K3 synthesizers
are still referenced to the TCXO-3 all the time. So during the
interval between frequency corrections, roughly every four seconds,
the radio frequency is controlled by the TCXO-3. So frequency drift
rate is not affected by the K3EXREF during this interval and only
periodically corrected.

But this does keep the TCXO within 0.05 ppm vs 0.5 ppm.

I was a beta tester and you can see my test results here:
http://www.kl7uw.com/K3EXREF.htm

The largest error observed was +2.5 Hz on 6m.
------------------------------

Message: 29
Date: Fri, 20 May 2011 08:58:55 -0700 (PDT)
From: Dan AE9K <[hidden email]>
Subject: Re: [Elecraft] Installed K3EXREF
To: [hidden email]
Message-ID: <[hidden email]>
Content-Type: text/plain; charset=us-ascii

This may be a naive question but...

If the K3EXREF keeps the K3's reference oscillator within 2 Hz, then what
value is there in using the K3EXREF in conjunction with the KTCXO3 instead
of just the native K3 oscillator?

K3EXREF: 2 Hz error @ 14 MHz : 0.1 ppm
K3TCXO3: 7 Hz error @ 14 MHz : 0.5 ppm

Is the stability in ppm an instantaneous measurement of random error and not
a measurement potential drift over some time delta?

If this is true then using the K3EXREF alone presumably would exhibit the 5
ppm error of the native oscillator in the 4 to 8 second gaps between K3EXREF
syncs. This would make the case for replacing the native oscillator with the
K3TCXO3.

If the stability is measured over time, however, then the K3EXREF and native
oscillator would appear to be sufficient since oscillator drift is
insignificant in the 4 to 8 second time span.

Just curious.

Dan
AE9K

73, Ed - KL7UW, WD2XSH/45
======================================
BP40IQ 500 KHz - 10-GHz www.kl7uw.com
EME: 50-1.1kw?, 144-1.4kw, 432-100w, 1296-testing*, 3400-?
DUBUS Magazine USA Rep [hidden email]
======================================
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Dan AE9K

Re: Installed K3EXREF

Ed,

Thanks for the response. Let me clarify my question. I'm wondering if the KTCXO3 0.5 ppm oscillator can be omitted and still get great results with the K3EXREF and the standard 5 ppm oscillator. This is of interest because I intend to acquire the K3EXREF but do not have the KTCXO3 and would prefer not to buy it if it doesn't add any benefit.

My logic: If the K3EXREF adjusts the TCXO (via REF CAL) every 4 seconds, then why not let it adjust the standard K3 TCXO instead of having it adjust the optional KTCXO3 oscillator?

Even though the two oscillators differ by an order of magnitude in their error, does that error make a difference when the K3EXREF adjustments are every four seconds?

ps - During your beta testing were you using the standard K3 5 ppm oscillator or the KTCXO3 0.5 ppm oscillator? I didn't find mention of that on your web site.

Dan
AE9K

Guy, K2AV

Re: Installed K3EXREF

I would use the KTCXO3 if I ever intended to use it apart from the
reference source. I take my K3 to multi op contest weekends, field
day, IOTA dxpedition class.

On Fri, May 20, 2011 at 10:47 PM, Dan AE9K <[hidden email]> wrote:

> Ed,
>
> Thanks for the response. Let me clarify my question. I'm wondering if the
> KTCXO3 0.5 ppm oscillator can be omitted and still get great results with
> the K3EXREF and the standard 5 ppm oscillator. This is of interest because
> I intend to acquire the K3EXREF but do not have the KTCXO3 and would prefer
> not to buy it if it doesn't add any benefit.
>
> My logic: If the K3EXREF adjusts the TCXO (via REF CAL) every 4 seconds,
> then why not let it adjust the standard K3 TCXO instead of having it adjust
> the optional KTCXO3 oscillator?
>
> Even though the two oscillators differ by an order of magnitude in their
> error, does that error make a difference when the K3EXREF adjustments are
> every four seconds?
>
> ps - During your beta testing were you using the standard K3 5 ppm
> oscillator or the KTCXO3 0.5 ppm oscillator? I didn't find mention of that
> on your web site.
>
> Dan
> AE9K
>
> --
> View this message in context: http://elecraft.365791.n2.nabble.com/Installed-K3EXREF-tp6188288p6388532.html
> Sent from the Elecraft mailing list archive at Nabble.com.
> ______________________________________________________________
> Elecraft mailing list
> Home: http://mailman.qth.net/mailman/listinfo/elecraft
> Help: http://mailman.qth.net/mmfaq.htm
> Post: mailto:[hidden email]
>
> This list hosted by: http://www.qsl.net
> Please help support this email list: http://www.qsl.net/donate.html
>

k.igor

Re: Installed K3EXREF

In reply to this post by Dan AE9K

Dan,
I cannot imagine ham radio application that requires stability and accuracy
better than standard K3 oscillator with K3EXREF, provided your reference
oscillator is good enough for the toughest amateur radio application. Don't
forget, with K3EXREF you still need some external reference oscillator,
either good calibrated OCXO, some kind of timing module based on GPS
technology (like Thunderbolt etc.) or Rubidium oscillator, like
Symmetricom/Datum LPRO or one of the FEI products. Note that in case of
OCXO, it will need to be periodically calibrated against better reference.
However, if you plan to use K3 on the go without k3EXREF and need better
accuracy/stability, then you probably want to consider KTCXO3. Using
permanently KTCXO3 with K3EXREF seems like waste of money, this will not
give much advantage over same setup with standard K3 oscillator.
73,
Igor, N1YX

-----Original Message-----
From: [hidden email]
[mailto:[hidden email]] On Behalf Of Dan AE9K
Sent: Friday, May 20, 2011 10:48 PM
To: [hidden email]
Subject: Re: [Elecraft] Installed K3EXREF

Ed,

Thanks for the response. Let me clarify my question. I'm wondering if the
KTCXO3 0.5 ppm oscillator can be omitted and still get great results with
the K3EXREF and the standard 5 ppm oscillator. This is of interest because
I intend to acquire the K3EXREF but do not have the KTCXO3 and would prefer
not to buy it if it doesn't add any benefit.

My logic: If the K3EXREF adjusts the TCXO (via REF CAL) every 4 seconds,
then why not let it adjust the standard K3 TCXO instead of having it adjust
the optional KTCXO3 oscillator?

Even though the two oscillators differ by an order of magnitude in their
error, does that error make a difference when the K3EXREF adjustments are
every four seconds?

ps - During your beta testing were you using the standard K3 5 ppm
oscillator or the KTCXO3 0.5 ppm oscillator? I didn't find mention of that
on your web site.

Dan
AE9K

--
View this message in context:
http://elecraft.365791.n2.nabble.com/Installed-K3EXREF-tp6188288p6388532.htm
l
Sent from the Elecraft mailing list archive at Nabble.com.
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Brett Howard

Re: Installed K3EXREF

In reply to this post by Dan AE9K

I was one of the beta testers and I tested the unit with the standard
oscillator. I haven't run into any issues and found the fixed error
across all bands to be quite nice. I never saw more than about 3Hz of
error no matter the frequency on the VFO dial. Thats not to mean that
if you have a standard oscillator that is at the outside of its bell
that you may not have enough pull with the KEXTREF3 to pull things
into place. Personally I never ran into this issue in my testing
however I will probably also get the tighter tolerance rock for use
when away from the 10Mhz reference. I find it really nice to know
that the radio is on frequency... However the P3 still has to warm up
before its frequency reference is accurate... ;)

~Brett (N7MG)

On Fri, May 20, 2011 at 7:47 PM, Dan AE9K <[hidden email]> wrote:

123