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A new Elecraft product?

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Ken G Kopp

A new Elecraft product?

There appears to be interest in external frequency standards to enhance the
already outstanding stability of the K3.

Would an Elecraft accessory that uses the clocking from the GPS system be a
viable product? Perhaps hidden away in the P3 cabinet if there isn't
suffucient space in a "loaded" K3.

73

Ken - K0PP
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David Pratt

Re: A new Elecraft product?

No, I don't think so, Ken. There are plenty of frequency standards
already available. In any case, we would not want to direct Elecraft's
attention away from developing the K4 ;-)

Your suggestion of putting it in the P3 box is not practical. You make
the assumption that everyone that has a K3 also has a P3. Not so.

73 de David G4DMP

In a recent message, Ken G Kopp <[hidden email]> writes
>There appears to be interest in external frequency standards to enhance the
>already outstanding stability of the K3.
>
>Would an Elecraft accessory that uses the clocking from the GPS system be a
>viable product? Perhaps hidden away in the P3 cabinet if there isn't
>suffucient space in a "loaded" K3.

--
+ - - - - - - - - - - - - - - - - +
| David M Pratt, Kippax, Leeds. |
| Website: http://www.g4dmp.co.uk |
+ - - - - - - - - - - - - - - - - +

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alsopb

Re: A new Elecraft product?

In reply to this post by Ken G Kopp

Ken,

There is an Elecraft product called the TCXO. It is capable of
temperature stabilization BUT Elecraft has not implemented that function.

Perhaps though should be given to implementing the temperature
compensation capability. My understanding is that there is some
difficulty in doing that and maintaining low phase noise.

73 de Brian/K3KO

On 10/15/2014 21:06, Ken G Kopp wrote:

> There appears to be interest in external frequency standards to enhance the
> already outstanding stability of the K3.
>
> Would an Elecraft accessory that uses the clocking from the GPS system be a
> viable product? Perhaps hidden away in the P3 cabinet if there isn't
> suffucient space in a "loaded" K3.
>
> 73
>
> Ken - K0PP
> ______________________________________________________________

Ken G Kopp

Re: A new Elecraft product?

Brian,

I'm aware of the TCXO ... it's the only option I don't have ... thought it
might be just a small step to synch it to a GPS receiver instead of some
form of after-market / surplus standard.

Each cellular site has a GPS receiver for clocking, but I have no idea of
the size of the unit, or if the resulting accuracy is better / worse than
one of the surplus units.

73 - Ken
Ken,

There is an Elecraft product called the TCXO. It is capable of temperature
stabilization BUT Elecraft has not implemented that function.

Perhaps though should be given to implementing the temperature compensation
capability. My understanding is that there is some difficulty in doing
that and maintaining low phase noise.

73 de Brian/K3KO

On 10/15/2014 21:06, Ken G Kopp wrote:

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Don Wilhelm-4

Re: A new Elecraft product?

In reply to this post by alsopb

Brian,

The High Stability TCXO (1 ppm) is not a separate Elecraft product - it
is an option for the K3 offering better specs than the stock TCXO (5ppm)
- yes, both are a TCXO.

The temperature stability was found to be far better than the 1ppm
specification without the temperature compensation routine, so
implementation of that K3 routine was dropped from the plan (and also
from the manual).

73,
Don W3FPR

On 10/16/2014 7:39 AM, Brian wrote:
> Ken,
>
> There is an Elecraft product called the TCXO. It is capable of
> temperature stabilization BUT Elecraft has not implemented that function.
>
> Perhaps though should be given to implementing the temperature
> compensation capability. My understanding is that there is some
> difficulty in doing that and maintaining low phase noise.
>

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alsopb

Re: A new Elecraft product?

Don,

The issue isn't whether the TCXO is an improvement over the standard.

The issue is whether the TCXO is good enough for some of the wide range
of uses the K3 is put.

What you are hearing here is that it isn't. Elecraft has responded with
the external locking option. That option, being a discontinuous
correction, one has some significant disadvantages to some.

My original posting on this issue was related to the locking option. It
only seemed reasonable to have it do a sanity check on the difference
between the internal and reference oscillator implied correction before
doing a correction. Why do the correction is the external oscillator is
warming up and 250 Hz off initially? The K3 also drifts during warmup
with both the standard and TCXO. This amounts to between 20 and 50 Hz
(@ 10 MHz) for the first 15 minutes. Why do the correction until the K3
has is relatively stable. Perhaps the external locking should not be
done for say the first 15 minutes after K3 turn on?

73 de Brian/K3KO

On 10/16/2014 12:06, Don Wilhelm wrote:

> Brian,
>
> The High Stability TCXO (1 ppm) is not a separate Elecraft product - it
> is an option for the K3 offering better specs than the stock TCXO (5ppm)
> - yes, both are a TCXO.
>
> The temperature stability was found to be far better than the 1ppm
> specification without the temperature compensation routine, so
> implementation of that K3 routine was dropped from the plan (and also
> from the manual).
>
> 73,
> Don W3FPR
>
> On 10/16/2014 7:39 AM, Brian wrote:
>> Ken,
>>
>> There is an Elecraft product called the TCXO. It is capable of
>> temperature stabilization BUT Elecraft has not implemented that function.
>>
>> Perhaps though should be given to implementing the temperature
>> compensation capability. My understanding is that there is some
>> difficulty in doing that and maintaining low phase noise.
>>
>
> ______________________________________________________________
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>
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>

Elecraft mailing list

Re: A new Elecraft product?

I've been running with a Trimble Thunderbolt GPSDO and the Elecraft TCXO for
over a year now. I'm in a position to keep the Trimble powered up continuously,
but I can certainly understand the angst of those who can't. It's a trade-off. I also
keep an old laptop running, and have Lady Heather running on it to keep an eye
on things. Do I really *need* that level of precision? Probably not, for my current
operational needs (ordinary/casual HF operations, no VHF/UHF transverters, etc.).
Bear in mind that the GPS receiver decodes the signals from the various satellites
that can be seen at any given time, and then generates an error signal to its
internal TCXO running at 10MHz, which then spits out both a 10MHz signal, which
we typically feed to the K3EXREF, and a 1 pulse per second square wave (which
I'd love to feed to a wall clock). The issue is the 100 second warm-up time for the
Trimble's TCXO, not the GPS receiver, although the latter usually needs, like any
other GPS unit, a few moments to listen for, and synchronize, to satellite signals.

There are a couple of system design issues inherent in this, however. First, the
Trimble requires a triple-voltage power supply: +5V, +12V, and -12V. I'm using a
cheap commodity power supply that is in itself powered from AC mains (117V/60Hz).
So, if I lose AC mains, I lose the Trimble, and have to hope that the K3 and its TCXO
will stay accurate enough while I'm operating it off of a battery. For those purposes,
a few Hz isn't going to get me kicked out of an amateur net, but if I were a MARS
member (which I'm not), it might be dicey - I'd have to do an analysis.

The third issue, which has not been touched on AFAICT, is that the Trimble (and
probably its competition) really likes to have an external antenna. In my case, I was
lucky to find the actual Trimble antenna (which includes a preamp), and it's served
me well at both of my QTHs (So. Fla. and western NC), which is a square puck
about 2 inches/5 cm on a side with a magnetic base and 25 feet of RG-174/U coax.
It works, and it was cheap on E-Bay, so I'm happy so far.

So, a potential add-on product for the K3 could involve one of the newer single-board
GPSDOs (e.g., Sematron GPS-1000 or one of its competitors), feeding the K3EXREF
board internally and using the K3EXREF's input port on the back panel of the K3
for its antenna port. However, I haven't even priced one of these units, never mind
purchased and evaluated it, much less actually attempted to install it in my rig. So,
far, it's just an idea or springboard for further discussion. Brian makes an excellent
point about the overall temperature requirements, as well as the behavior of the K3
running with its TCXO synchronized to a potentially unsuitable reference signal. These
can be tricky design issues, and I'm sure Wayne and Eric have enough other things on
their list to tackle at this point, without a digression into this quagmire.

Just my 20 millidollars' worth,

73 de N1HO
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Don Wilhelm-4

Re: A new Elecraft product?

In reply to this post by alsopb

I am hearing that you have an external reference that takes some time to
warm up after you turn it on, and that causes the K3 to move frequency
with the warmup drift of the external reference.

If the external reference is stable when the K3 is turned on, there is
no need for the K3 to ignore the external reference.

If the K3 were to ignore the external reference for 15 to 20 minutes
after the K3 is turned on, then it would have to do the same thing after
every power cycle. If I were using an external reference, I would not
want the K3 to do that. If I use an external reference, I would want
that reference to be accurate at all times, I think the best answer is
to power the reference continuously.

As a parallel, the high stability 10 MHz reference oscillator in my
universal counter is powered whenever the counter is plugged in - when I
use the front panel switch to turn the counter on, I can trust its
accuracy without waiting for it to warm up. If I used an external
reference with the K3, I would want the same results.

73,
Don W3FPR

On 10/16/2014 8:39 AM, Brian wrote:

> Don,
>
> The issue isn't whether the TCXO is an improvement over the standard.
>
> The issue is whether the TCXO is good enough for some of the wide
> range of uses the K3 is put.
>
> What you are hearing here is that it isn't. Elecraft has responded
> with the external locking option. That option, being a discontinuous
> correction, one has some significant disadvantages to some.
>
> My original posting on this issue was related to the locking option.
> It only seemed reasonable to have it do a sanity check on the
> difference between the internal and reference oscillator implied
> correction before doing a correction. Why do the correction is the
> external oscillator is warming up and 250 Hz off initially? The K3
> also drifts during warmup with both the standard and TCXO. This
> amounts to between 20 and 50 Hz (@ 10 MHz) for the first 15 minutes.
> Why do the correction until the K3 has is relatively stable. Perhaps
> the external locking should not be done for say the first 15 minutes
> after K3 turn on?
>
> 73 de Brian/K3KO
>
> On 10/16/2014 12:06, Don Wilhelm wrote:
>> Brian,
>>
>> The High Stability TCXO (1 ppm) is not a separate Elecraft product - it
>> is an option for the K3 offering better specs than the stock TCXO (5ppm)
>> - yes, both are a TCXO.
>>
>> The temperature stability was found to be far better than the 1ppm
>> specification without the temperature compensation routine, so
>> implementation of that K3 routine was dropped from the plan (and also
>> from the manual).
>>
>> 73,
>> Don W3FPR
>>
>> On 10/16/2014 7:39 AM, Brian wrote:
>>> Ken,
>>>
>>> There is an Elecraft product called the TCXO. It is capable of
>>> temperature stabilization BUT Elecraft has not implemented that
>>> function.
>>>
>>> Perhaps though should be given to implementing the temperature
>>> compensation capability. My understanding is that there is some
>>> difficulty in doing that and maintaining low phase noise.
>>>
>>
>> ______________________________________________________________
>> 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
>> Message delivered to [hidden email]
>>
>>
>> -----
>> No virus found in this message.
>> Checked by AVG - www.avg.com
>> Version: 2012.0.2247 / Virus Database: 4031/7897 - Release Date:
>> 10/16/14
>>
>>
>
> ______________________________________________________________
> Elecraft mailing list
> Home: http://mailman.qth.net/mailman/listinfo/elecraft
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> Message delivered to [hidden email]
>

vk2rq

Re: A new Elecraft product?

In reply to this post by Elecraft mailing list

With this recent discussion around frequency references, some on this reflector may be interested in this GPS-locked agile frequency reference module that will cost you less than $30 delivered:
https://sites.google.com/site/g4zfqradio/u-blox_neo-6-7

The output is programable from 1Hz up to 10MHz. You can't use it directly to drove the 10MHz reference input of the K3; if the selected output frequency doesn't divide evenly into 48MHz, then you will get some short-term jitter in the output that you would need to clean up with some sort of TXCO PLL type of arrangement. But it is great for calibrating your frequency counter (the long gating time averages out any short term jitter), and the output is rock-steady and accurate source to zero-beat your radio against if you select an output like eg. 1, 3, 4, 6 or 8MHz. Output is a square wave, so harmonics could also be used.

73,
Matt VK2RQ

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Edward R Cole

Re: A new Elecraft product?

In reply to this post by Ken G Kopp

I assume anyone interested in this topic is reading all the
post...so, I randomly chose Brian's post to reply to:

First off, I read a lot of theorizing about the K3 TCXO's and The
K3EXREF. I was a field tester of the EXREF and have had it in
operation continuously since installing it...what follows is not theory:

I have a mw frequency counter that is good to 26-GHz reading down to
1-Hz accuracy (that is 25 parts per billion). The counter has an
internal TCXO which may run whenever the unit is plugged in (I
haven't checked so that is a guess). What isn't is that the counter
reads my rubidium reference oscillator as exactly 10-MHz. The Rb
stability (after warm up) is +/-5 E-11 = 5/100,000,000,000 Hz. This
is not as good a standard as using a GPS receiver but certainly good
enough for most of us (assuming you are not active on >10-GHz).

My stations 10-MHz reference is a $45 e-bay surplus Russian OCXO with
+/-5 E-12 short-term stability (after warm up). I run it
continuously on a battery that is float charged by my station 12v PS,
thus no wait when I turn on my K3/10.

You want to install the TCXO-3 (option) if you are going to install
the EXREF. The EXREF provides a reference frequency for the TCXO to
check against. The K3 uses the TCXO as reference osc for its DDS
VFO's and other LO's. The stability of the K3 is that of the model
TCXO you have installed, so if you are running the TCXO-3 that is
listed (pg73 of the manual) as having +/- 0.5 ppm or we could write
that +/- 5 E-7. Using 28-MHz as an example, that means the radio
keeps to +/- 14 Hz if 0.5 ppm is being realized.

The EXREF improves the stability by periodically checking the
frequency of the TCXO against that of an external 10-MHz reference
and generating a correction for the TCXO to bring it back to
48.380.000 MHz. This happens about every 4-seconds so the TCXO
drifts normally at 0.5 ppm in between times. That results in about
2-Hz drift, so the K3 is never more than +/-2 Hz off frequency when
using the EXREF. 2-Hz is approximately 0.1 ppm.

There is a momentary frequency step when the EXREF does its check and
compensation. This has been a criticism by many "purist". But I
have not had this cause any issues when I am running JT65C on 1296-MHz eme.

If +/- 28 Hz is acceptable for your ham radio use, then you will
probably be happy just running with the TCXO-3. If you need better
stability the EXREF will probably suffice (it does for me).

Oh some suggest that the K3 will still drift at power-up because the
TCXO-3 is warming up. If you do not use the EXREF that is true. I
see about 80-Hz movement after warm up. But the K3 is kept to +/- 2
Hz from start by the EXREF so it does not matter that the TCXO has
drift because that is compensated immediately at start up (if your
10-MHz reference is stable). And it continues to be corrected every
4-seconds after that.

OK, sorry for the long tutorial, but this should remove all
specializing on this topic.

73, Ed - KL7UW
600meters to 3cm (on 17 bands)
WD2XSH/45 experimental license for 600m
144-eme
1296-eme
--------------
From: Brian <[hidden email]>
To: [hidden email]
Subject: Re: [Elecraft] A new Elecraft product?
Message-ID: <[hidden email]>
Content-Type: text/plain; charset=utf-8; format=flowed

Don,

The issue isn't whether the TCXO is an improvement over the standard.

The issue is whether the TCXO is good enough for some of the wide range
of uses the K3 is put.

What you are hearing here is that it isn't. Elecraft has responded with
the external locking option. That option, being a discontinuous
correction, one has some significant disadvantages to some.

My original posting on this issue was related to the locking option. It
only seemed reasonable to have it do a sanity check on the difference
between the internal and reference oscillator implied correction before
doing a correction. Why do the correction is the external oscillator is
warming up and 250 Hz off initially? The K3 also drifts during warmup
with both the standard and TCXO. This amounts to between 20 and 50 Hz
(@ 10 MHz) for the first 15 minutes. Why do the correction until the K3
has is relatively stable. Perhaps the external locking should not be
done for say the first 15 minutes after K3 turn on?

73 de Brian/K3KO

73, Ed - KL7UW
http://www.kl7uw.com
"Kits made by KL7UW"
Dubus Mag business:
[hidden email]

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Elecraft mailing list

Re: A new Elecraft product?

Thank you for the explanation.

From: Edward R Cole <[hidden email]>
To: [hidden email]
Sent: Friday, October 17, 2014 3:17 PM
Subject: Re: [Elecraft] A new Elecraft product?

I assume anyone interested in this topic is reading all the
post...so, I randomly chose Brian's post to reply to:

First off, I read a lot of theorizing about the K3 TCXO's and The
K3EXREF. I was a field tester of the EXREF and have had it in
operation continuously since installing it...what follows is not theory:

I have a mw frequency counter that is good to 26-GHz reading down to
1-Hz accuracy (that is 25 parts per billion). The counter has an
internal TCXO which may run whenever the unit is plugged in (I
haven't checked so that is a guess). What isn't is that the counter
reads my rubidium reference oscillator as exactly 10-MHz. The Rb
stability (after warm up) is +/-5 E-11 = 5/100,000,000,000 Hz. This
is not as good a standard as using a GPS receiver but certainly good
enough for most of us (assuming you are not active on >10-GHz).

My stations 10-MHz reference is a $45 e-bay surplus Russian OCXO with
+/-5 E-12 short-term stability (after warm up). I run it
continuously on a battery that is float charged by my station 12v PS,
thus no wait when I turn on my K3/10.

You want to install the TCXO-3 (option) if you are going to install
the EXREF. The EXREF provides a reference frequency for the TCXO to
check against. The K3 uses the TCXO as reference osc for its DDS
VFO's and other LO's. The stability of the K3 is that of the model
TCXO you have installed, so if you are running the TCXO-3 that is
listed (pg73 of the manual) as having +/- 0.5 ppm or we could write
that +/- 5 E-7. Using 28-MHz as an example, that means the radio
keeps to +/- 14 Hz if 0.5 ppm is being realized.

The EXREF improves the stability by periodically checking the
frequency of the TCXO against that of an external 10-MHz reference
and generating a correction for the TCXO to bring it back to
48.380.000 MHz. This happens about every 4-seconds so the TCXO
drifts normally at 0.5 ppm in between times. That results in about
2-Hz drift, so the K3 is never more than +/-2 Hz off frequency when
using the EXREF. 2-Hz is approximately 0.1 ppm.

There is a momentary frequency step when the EXREF does its check and
compensation. This has been a criticism by many "purist". But I
have not had this cause any issues when I am running JT65C on 1296-MHz eme.

If +/- 28 Hz is acceptable for your ham radio use, then you will
probably be happy just running with the TCXO-3. If you need better
stability the EXREF will probably suffice (it does for me).

Oh some suggest that the K3 will still drift at power-up because the
TCXO-3 is warming up. If you do not use the EXREF that is true. I
see about 80-Hz movement after warm up. But the K3 is kept to +/- 2
Hz from start by the EXREF so it does not matter that the TCXO has
drift because that is compensated immediately at start up (if your
10-MHz reference is stable). And it continues to be corrected every
4-seconds after that.

OK, sorry for the long tutorial, but this should remove all
specializing on this topic.

73, Ed - KL7UW
600meters to 3cm (on 17 bands)
WD2XSH/45 experimental license for 600m
144-eme
1296-eme
--------------
From: Brian <[hidden email]>
To: [hidden email]
Subject: Re: [Elecraft] A new Elecraft product?
Message-ID: <[hidden email]>
Content-Type: text/plain; charset=utf-8; format=flowed

Don,

The issue isn't whether the TCXO is an improvement over the standard.

The issue is whether the TCXO is good enough for some of the wide range
of uses the K3 is put.

What you are hearing here is that it isn't. Elecraft has responded with
the external locking option. That option, being a discontinuous
correction, one has some significant disadvantages to some.

My original posting on this issue was related to the locking option. It
only seemed reasonable to have it do a sanity check on the difference
between the internal and reference oscillator implied correction before
doing a correction. Why do the correction is the external oscillator is
warming up and 250 Hz off initially? The K3 also drifts during warmup
with both the standard and TCXO. This amounts to between 20 and 50 Hz
(@ 10 MHz) for the first 15 minutes. Why do the correction until the K3
has is relatively stable. Perhaps the external locking should not be
done for say the first 15 minutes after K3 turn on?

73 de Brian/K3KO

73, Ed - KL7UW
http://www.kl7uw.com
"Kits made by KL7UW"
Dubus Mag business:
[hidden email]

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