[K3] KTCXO3-1 and standard TXCO drift rates

[Bill Frantz]

Since I started using the K3 for PSK-31 contacts, I've noticed
that I have to make many fine tuning adjustments during weak
signal QSOs. I don't remember having to make as many using the
Small Wonder Labs PSK-20 direct conversion receiver. I am using
Data-A mode and a SignaLink USB "sound card" to a MacBook Pro
running cocoaModem.


There are several possibilities here:

   * My memory is bad.
   * The other station is drifting.
   * The effect is caused by the SignaLink.#
   * The effect is caused by the K3.

# The signaLink is the same one I used with the PSK-20.

I have the stock 5ppm TXCO. I try to let the K3 warm up for 10
minutes before serious use, and I have observed the drift after
several hours of operation.

How do the short-term (5 to 10 minute) drift rates of the two
TXCOs compare? I think I need stability to about 1/2 to 1 Hz for
the duration of the QSO.

Cheers - Bill, AE6JV

-----------------------------------------------------------------------
Bill Frantz        | I like the farmers' market   | Periwinkle
[phone]      | because I can get fruits and | 16345
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CA 95032

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[Don Wilhelm-4]

Bill,

I would suggest that "The other station is drifting" is the best answer.
The drift of either the 1ppm or 5ppm TCXO is based on temperature, and
not on other factors - the 1% TCXO is better, but it is all with respect
to temperature, not any other considerations.

The 5 ppm TCXO vs the 1ppm TCXO should not be significant for PSK31 -
the only caveat I can offer is that if your shack ambient temperature is
changing rapidly, then you can consider that your K3 may be the cause of
the drift, but if your shack temperature is relatively constant, the
stock 5 ppm TCXO should perform quite nicely - it is all about
temperature changes.

The more likely scenario is that the the other station has not separated
his TX frequency from his RX frequency, and the result of the
accumulated Re-tuning  (and drift if any) results in the signals
"climbing the band".  To prevent that, once a QSO has been established,
turn off auto-tune and you should be able to continue your QSO.

73,
Don W3FPR

On 4/5/2012 5:54 PM, Bill Frantz wrote:

> Since I started using the K3 for PSK-31 contacts, I've noticed
> that I have to make many fine tuning adjustments during weak
> signal QSOs. I don't remember having to make as many using the
> Small Wonder Labs PSK-20 direct conversion receiver. I am using
> Data-A mode and a SignaLink USB "sound card" to a MacBook Pro
> running cocoaModem.
>
>
> There are several possibilities here:
>
>     * My memory is bad.
>     * The other station is drifting.
>     * The effect is caused by the SignaLink.#
>     * The effect is caused by the K3.
>
> # The signaLink is the same one I used with the PSK-20.
>
> I have the stock 5ppm TXCO. I try to let the K3 warm up for 10
> minutes before serious use, and I have observed the drift after
> several hours of operation.
>
> How do the short-term (5 to 10 minute) drift rates of the two
> TXCOs compare? I think I need stability to about 1/2 to 1 Hz for
> the duration of the QSO.
>
> Cheers - Bill, AE6JV
>
> -----------------------------------------------------------------------
> Bill Frantz        | I like the farmers' market   | Periwinkle
> [phone]      | because I can get fruits and | 16345
> Englewood Ave
> www.pwpconsult.com | vegetables without stickers. | Los Gatos,
> CA 95032
>
> ______________________________________________________________
> 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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[Bill Frantz]

Thanks for your answer Don. I guess I'll put the KTCXO3-1 lower
on my wish list.

Fortunately, with a little care cocoaModem automatically
preserves the transmit frequency. I also help it by using the
second receiver to retune the signal leaving the transmit
frequency unchanged. Being able to reinterpret the last 20
seconds or so of recorded audio with a slightly different tuning
also helps.

Cheers - Bill, AE6JV

On 4/5/12 at 16:57, [hidden email] (Don Wilhelm) wrote:

>The more likely scenario is that the the other station has not
>separated his TX frequency from his RX frequency, and the
>result of the accumulated Re-tuning  (and drift if any) results
>in the signals "climbing the band".  To prevent that, once a
>QSO has been established, turn off auto-tune and you should be
>able to continue your QSO.
-----------------------------------------------------------------------
Bill Frantz        | Truth and love must prevail  | Periwinkle
[phone]      | over lies and hate.          | 16345
Englewood Ave
www.pwpconsult.com |               - Vaclav Havel | Los Gatos,
CA 95032

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[Robert Young]

The AFC option in many of the digital software programs will cause the frequency to change. I use DM780 and if I have the AFC option enabled, it will cause my frequency to shift. In noisy band conditions it is very noticeable. Its as if the AFC is chasing the static crashes.

If both stations have that software option enabled, then its very likely that it has nothing to do with your rigs frequency stability.  Its actually the software causing the frequency to change. Take a look at that the next time you find yourself chasing a station up or down the band during a PSK contact.

73 de W9MO
Bob Young

[Tony Estep]

On Sat, Apr 7, 2012 at 9:15 AM, Robert Young <[hidden email]> wrote:

> ...If both stations have that software option enabled...

=======
Yep, that's almost certainly what is happening, making it seem as if
something is drifting. A little time spent operating PSK and/or reading the
mail on PSK contacts will reveal that this happens on many QSOs, especially
at the beginning. I think it's safe to say that your K3 isn't drifting.

If you want a more robust answer with regard to your signal drift, fire up
WSPR. First, receive a bunch of signals and not the numbers in your drift
column. They should be mostly 0, with a few -1 and +1. Then transmit and
see what the other guys say about your drift. Again, most should say 0 with
a few -1 and/or +1.

Tony KT0NY

--
http://www.isb.edu/faculty/facultydir.aspx?ddlFaculty=352
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