[Elecraft] K3 drift

[Erik N Basilier]

Jim,

If you aren't using digital modes, you probably don't need to worry about 
stability, but...

* Before I got a K3, I mostly used a TS-570 for digital modes, with somewhat 
limited success. It turned out it was drifting way too much, even during a 
quick qso. Transmitting would raise the temperature, causing the frequency 
to change, and during receive the frequency would gradually go back again. I 
paid about $200 to correct it by installing the optional Kenwood tcxo. I 
also noted, like many TS-570 owners, that the fan didn't kick in soon 
enough. I corrected that with a trimpot added to the rig. Before the 
upgrade, the size of the drift on a long transmission was way greater than 
going from perfect copy to no copy.

* Based on the above experience I ordered my K3 with the upgraded tcxo. 
Digital mode copy has been great. As I recall, the Elecraft option was a 
bargain compared to the Kenwood one.

* The other day I had a cw qso with another K3 user on 40. He drifted so I 
had to adjust my RIT 40 Hz during the qso. I was using a very narrow 
bandwidth setting. (Well, at least I *assume* that it was the other guy 
drifting...)

* The spec says that the standard K3 tcxo will vary no more than 5 ppm going 
from 0-50 degrees C. Suppose the rig warms 10 degrees C during warmup. That 
would be 1 ppm or 14 Hz at 14 MHz. That's enough to be very noticeable with 
PSK31.

73,
Erik K7TV

----- Original Message ----- 
From: "JIM DAVIS" <nn6ee at astound.net>
To: "John A. McCabe" <johnamccabe at verizon.net>; <elecraft at mailman.qth.net>
Sent: Tuesday, December 30, 2008 2:08 PM
Subject: Re:Re: [Elecraft] K3 drift




> Steven.Zabarnick at notes.udayton.edu wrote:
>> During the past week I have noticed my K3 drifting during the first 20
>> seconds after power up. I hadn’t noticed this previously in my three 
>> month
>> old K3 (SN 1672), so I’m wondering if this is normal? With winter here it
>> is colder in my basement shack (maybe down 55 F), so perhaps that could
>> explain the drift.
>>
>> I haven't measured the drift, but definitely have not noticed it in the
>> past.
>>
>> Does anyone else observe this drift? Is this normal during warmup?
>>
>> Steve N9SZ
>>   ------------------------------------------------------------------------
Steve,
With your question in mind is it REALLY NECESSARY to have temp. comp oven 
for our
rather stable rigs to begin with???  Our newer rigs a now measured in "PPM" 
instead
of KHZ. per hr. drift factor!!!

It seems that in our hobby why in the heck would any individual really need 
a TCXO or whatever
in the first place?  As most ovens are only switched on when the rig is 
instead of being
on CONTINUOUSLY whether the main rig is ON or OFF!!!  Ovens really don't 
make that much
sense!

Jim/nn6ee


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