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Suggestions for 10 MHz Signal Source for the K3?

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dhhdeh

Suggestions for 10 MHz Signal Source for the K3?

Hi Everyone,

I am considering a K3EXREF just for fun, no other
reason.

Looking for suggestions for a reasonably priced 10
MHz external signal source.

Can anyone offer some suggestions? GPSDO? OCXO?
Rubidium Standard?

I have seen some used Trimble Thunderbolt GPSDO's
on eBay form China. I'm just not sure about the
wisdom of ordering any of these units.

Suggestions would be appreciated on or off the list.

73 de N1LQ-Dave

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Johnny Siu

Re: Suggestions for 10 MHz Signal Source for the K3?

I am also interested in that information . Could any of you share on this forum as 'OT'

Sent from my iPhone 4

David and Dianne on Comcast <[hidden email]> 於 2011年6月21日上午9:11 寫道：

> Hi Everyone,
>
> I am considering a K3EXREF just for fun, no other
> reason.
>
> Looking for suggestions for a reasonably priced 10
> MHz external signal source.
>
> Can anyone offer some suggestions? GPSDO? OCXO?
> Rubidium Standard?
>
> I have seen some used Trimble Thunderbolt GPSDO's
> on eBay form China. I'm just not sure about the
> wisdom of ordering any of these units.
>
> Suggestions would be appreciated on or off the list.
>
> 73 de N1LQ-Dave
>
> ______________________________________________________________
> 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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Jim-2

Re: Suggestions for 10 MHz Signal Source for the K3?

Me too!

Jim
Ke4wy

On Jun 20, 2011, at 9:31 PM, vr2xmc <[hidden email]> wrote:

> I am also interested in that information . Could any of you share on this forum as 'OT'
>
> Sent from my iPhone 4
>
> David and Dianne on Comcast <[hidden email]> 於 2011年6月21日上午9:11 寫道：
>
>> Hi Everyone,
>>
>> I am considering a K3EXREF just for fun, no other
>> reason.
>>
>> Looking for suggestions for a reasonably priced 10
>> MHz external signal source.
>>
>> Can anyone offer some suggestions? GPSDO? OCXO?
>> Rubidium Standard?
>>
>> I have seen some used Trimble Thunderbolt GPSDO's
>> on eBay form China. I'm just not sure about the
>> wisdom of ordering any of these units.
>>
>> Suggestions would be appreciated on or off the list.
>>
>> 73 de N1LQ-Dave
>>
>> ______________________________________________________________
>> 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

John Bekema

Re: Suggestions for 10 MHz Signal Source for the K3?

In reply to this post by dhhdeh

Hi,

Would this be interesting?

http://www.jrmiller.demon.co.uk/projects/ministd/frqstd.htm

OH2GBA,
John

2011/6/21 David and Dianne on Comcast <[hidden email]>:

Matt Zilmer

Re: Suggestions for 10 MHz Signal Source for the K3?

I'm using the Trimble Thunderbolt here, with good results. I ordered
two units from one of the eBay vendors. These shipped from within the
US and were less than $80 each.

eBay has a very well-structured buyer satisfaction policy. If you
choose this course, look carefully at the customer satisfaction index
your chosen vendor has earned via buyer feedback.

73,
matt W6NIA

On Tue, 21 Jun 2011 08:55:59 +0300, you wrote:

>Hi,
>
>Would this be interesting?
>
>http://www.jrmiller.demon.co.uk/projects/ministd/frqstd.htm
>
>OH2GBA,
>John
>
>2011/6/21 David and Dianne on Comcast <[hidden email]>:
>> Hi Everyone,
>>
>> I am considering a K3EXREF just for fun, no other
>> reason.
>>
>> Looking for suggestions for a reasonably priced 10
>> MHz external signal source.
>>
>> Can anyone offer some suggestions? GPSDO? OCXO?
>> Rubidium Standard?
>>
>> I have seen some used Trimble Thunderbolt GPSDO's
>> on eBay form China. I'm just not sure about the
>> wisdom of ordering any of these units.
>>
>> Suggestions would be appreciated on or off the list.
>>
>> 73 de N1LQ-Dave
>______________________________________________________________
>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

Dave, G4AON

Re: Suggestions for 10 MHz Signal Source for the K3?

In reply to this post by dhhdeh

Like I guess quite a few others, I have been down the high stability
reference route and currently have the following 10 MHz sources:

60 KHz (MSF and possibly WWV) locked plain crystal oscillator, it's
based on the G4JNT MK2 from RadCom (http://www.g4jnt.com/freqlock.htm).
It works well enough and is easy and cheap to build/align. The
limitation is the short term stability which is perhaps academic when
used to lock a HF transceiver and is around 1 part in 10^8 (same
stability as the older UK Quartzlock 198 KHz units), also I am not sure
how immune it would be in the presence of high levels of HF RF. Locks
and stable within 5 minutes or so from switch on, low current consumption.

Surplus rubidium... These appear from time to time, I was given one by a
local surplus dealer who seemed to have more than there was a market for
a few years ago. They are used in cellular and similar sites and are
probably good for quite a few hours of service, however they have a
finite life and appear on the surplus market when removed for upgrade or
on routine service, so don't pay much for one. Current drain is quite
high, typically needing 2 Amps at 24 Volts initially then dropping after
warm up. Stable around 15 ~ 20 minutes from switch on. Needs additional
power supply and cabinet/heatsink.

GPS controlled crystal oven... Mine appeared on eBay as a part home
built unit, there are a variety of these that pop up at times. Mine uses
a Toyo high stability OCXO and is superbly stable and will site in
perfect sync with the rubidium for days. Locked and stable around 15 ~
30 minutes from switch on, needs well sited external antenna (not one
sitting in the shack window). Current consumption around half that of a
rubidium when fitted with an OCXO. The best option of all for a long
term accurate reference.

If you want an OCXO there are currently several "double ovens" listed on
eBay.com for $45 including worldwide shipping from China. They need a
GPS or MSF/WWV locked oscillator to set accurately on frequency, warm up
time 15 ~ 30 minutes. High stability oscillators/sources can be compared
for phase/frequency with a dual beam oscilloscope, listening for a beat
note between them is not sufficient at this level of accuracy.

I don't plan to fit a K3EXREF, it seems like a nice idea but my K3 was
only 2 Hz off frequency at 50 MHz a few days ago and it hasn't been
adjusted for several months. My K3 has the KTCXO3-1 fitted and dates
from 2007, so the TCXO is fairly well aged by now.

73 Dave, G4AON
-----------------------
/I am considering a K3EXREF just for fun, no other
reason.

Looking for suggestions for a reasonably priced 10
MHz external signal source.

Can anyone offer some suggestions? GPSDO? OCXO?
Rubidium Standard?
<SNIP>
73 de N1LQ-Dave/

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hb9ari@bluewin.ch

Re: Suggestions for 10 MHz Signal Source for the K3?

In reply to this post by John Bekema

Hi John,

I'm using a G3RUH GPSDO for PC time setting and external 10MHz
reference, BUT not connected to my K3. I'm very satisfied with it.
I've not used this source for the K3, because i will not use the
"uCrtlr counting" method of "lock". Not sure if they are no
phase jump with this procedure? If a loop locked external reference
would be used, i certainly had connected the GPSDO.
I can understand that a "bad" external reference would lower the
very good phase noise figure of the K3.

My best 73,
Rudi, HB9ARI

On 21.06.2011 07:55, John Bekema wrote:

> Hi,
>
> Would this be interesting?
>
> http://www.jrmiller.demon.co.uk/projects/ministd/frqstd.htm
>
> OH2GBA,
> John
>
> 2011/6/21 David and Dianne on Comcast<[hidden email]>:
>> Hi Everyone,
>>
>> I am considering a K3EXREF just for fun, no other
>> reason.
>>
>> Looking for suggestions for a reasonably priced 10
>> MHz external signal source.
>>
>> Can anyone offer some suggestions? GPSDO? OCXO?
>> Rubidium Standard?
>>
>> I have seen some used Trimble Thunderbolt GPSDO's
>> on eBay form China. I'm just not sure about the
>> wisdom of ordering any of these units.
>>
>> Suggestions would be appreciated on or off the list.
>>
>> 73 de N1LQ-Dave
> ______________________________________________________________
> 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

Phil Kane-2

Re: Suggestions for 10 MHz Signal Source for the K3?

In reply to this post by Matt Zilmer

On 6/20/2011 11:35 PM, Matt Zilmer wrote:

> I'm using the Trimble Thunderbolt here, with good results. I ordered
> two units from one of the eBay vendors. These shipped from within the
> US and were less than $80 each.

What are the stability and accuracy of these devices in parts
per billion (10^12)? For 80 bucks you're not going to get a
rubidium or cesium standard, and zero-beating WWV will only
give you 1 part in 10^7 for a one-second measurement.

(Pardon my cynicism - my former network frequency standard
needed something like 1 part in 10^12 to do the job right.)

-- 73 de K2ASP - Phil Kane
Elecraft K2/100 s/n 5402

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P.B. Christensen

Re: Suggestions for 10 MHz Signal Source for the K3?

> What are the stability and accuracy of these devices in parts
> per billion (10^12)? For 80 bucks you're not going to get a
> rubidium or cesium standard

The $80 Trimble Thuderbolts as well as most GPS-DO units will do 10^-12. My
long-term 24 hour average is 10^-13 as reported by KE5FX software. So, as
long as the unit is locked to the GPS satellites, you can achieve long-term
Rubidium accuracy and about one decimal point away from cesium. Short-term
accuracy is around 10 ^-11 although one of my Thunderbolts shows 10^-12 at
start up and stays there. Locking the GPS-DO is as easy as throwing a tiny
GPS antenna out the window. Mine is resting on decorative brick wall and
fed with about 15 feet of RG-174. These antennas are plentiful on the
Internet for about USD $15 each.

True, the GPS-DO together with the K3 will not provide anywhere near the
accuracy stated above since the K3 will be frequency locked to the external
oscillator, and not phase locked. But, the output of the GPS-DO can be
split and fed to other transceivers (e.g., Icom 77700/7800, ADAT, etc), or
used as a test equipment reference. The Trimble Thunderbolt has
extraordinary phase noise performance as documented by KE5FX, typically
about 10 dB better than other GPS-DO units in the area of 10Hz to 1 kHz from
Fc. So, it may be overkill for the K3, but the device may come in handy at
a future date where its full potential can be exploited.

Paul, W9AC

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Matt Zilmer

Re: Suggestions for 10 MHz Signal Source for the K3?

In reply to this post by Phil Kane-2

Long term stability is in the 10^10 range, and short term one sees
<100 ppt generally. Quite often it's stable for minutes down to 25
ppt. The Thunderbolt is subject to GPS sats coming and going, and/or
noise from sats being too near the horizon. Each time a sat joins or
leaves the constellation, there is a little "few ppt" bounce in the
ppt.

I did some lab measurements against our Rb sources here at Magellan.
It takes special test equipment that we don't have to be able to sense
the difference. However, using a TIA locked to the GPSDO, the Rb
drifts in relation to the tune of +/- 50 ppt for a short term
observation. I don't have time to run it for months, just hours at a
time.

There will always be some question about the value of accurate
frequency sources used with ham radio. The K3 VFO has its own finite
resolution of 1 Hz, so that's the best quanta it can do anyway.
Watching the compensation using REF CAL, I can see it drift up from
49379.690 to 49379.776 over the span of several hours. But that's
just the compensation working against the TCXO and there is little or
no difference in pitch on air air for fixed sources like WWV or CHU.
There is no discernable beat note, since the heterodyne is below
audible frequencies. I don't see it on the s-meter either, so it's
probably around or below 1 Hz most of the time.

The K3 makes very fine adjustments using the source, only on RX I
believe, and only every few seconds.

The K144XV ref lock is still tied to the TCXO , not the external
reference. Dunno what the plan is to change this, but the TCXO-1 is
so much better than the xx PPM crystal injection oscillators at 116
and 118 MHz that it's remarkable. Maybe not yet good enough for
microwave work, but much better on 2m.

73,
matt W6NIA

On Tue, 21 Jun 2011 06:33:42 -0700, you wrote:

>On 6/20/2011 11:35 PM, Matt Zilmer wrote:
>
>> I'm using the Trimble Thunderbolt here, with good results. I ordered
>> two units from one of the eBay vendors. These shipped from within the
>> US and were less than $80 each.
>
> What are the stability and accuracy of these devices in parts
> per billion (10^12)? For 80 bucks you're not going to get a
> rubidium or cesium standard, and zero-beating WWV will only
> give you 1 part in 10^7 for a one-second measurement.
>
> (Pardon my cynicism - my former network frequency standard
> needed something like 1 part in 10^12 to do the job right.)
>
>-- 73 de K2ASP - Phil Kane
> Elecraft K2/100 s/n 5402
>
>______________________________________________________________
>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

Chip Stratton

Re: Suggestions for 10 MHz Signal Source for the K3?

In reply to this post by dhhdeh

I dont know how much accuracy you need, but if no more than 1 ppm or
so, find a Leader 823s frequency counter (S model is 1 ppm) cheap on
ebay. Its internal clock is 10 mHz and it will put that signal out via
a back panel BNC. You can zero beat it to WWV first to get it within a
few Hertz or better. Mine holds to much better than .5 ppm.

Other counters may have the same, I dont kniw, but this works for me.

On Monday, June 20, 2011, David and Dianne on Comcast
<[hidden email]> wrote:

P.B. Christensen

Re: Suggestions for 10 MHz Signal Source for the K3?

In reply to this post by P.B. Christensen

In holdover mode (e.g., no antenna connected), accuracy is typically
7x10^-10 for the Thunderbolt. So, still quite good. However, I don't
recall if the typical holdover specs require that the GPS-DO first initially
attain lock, then the antenna can be removed.

Paul, W9AC

----- Original Message -----
From: "Phil Kane" <[hidden email]>
To: "Paul Christensen" <[hidden email]>
Sent: Tuesday, June 21, 2011 11:30 AM
Subject: Re: [Elecraft] Suggestions for 10 MHz Signal Source for the K3?

> On 6/21/2011 6:49 AM, Paul Christensen wrote:
>
>> Locking the GPS-DO is as easy as throwing a tiny
>> GPS antenna out the window.
>
> True, but I was referring to applications where the standard is
> used as a "stand alone" device. My present comm room has
> little or no GPS or WWVB access because it is 3/4 underground.
> Were I to re-install it, I probably would have added a 14th
> antenna to the roof for GPS.... :-)
>
> That's what happens when one's experience was in the pre-GPS
> era......
>
> -- 73 de K2ASP - Phil Kane
> Elecraft K2/100 s/n 5402
>