[K2]: K2/100 Frequency Stability?

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[K2]: K2/100 Frequency Stability?

Rhulett
I built K2 s/n 06424 some time ago, then added KSB2 and finally converted it to 100W a few years ago.  Usually used it for CW only, but recently moved it to main operating position and started using it on 40M LSB mornings. To my chagrin, received comment few days ago that I was off frequency, and this morning confirmed with another op that I was 50 Hz low.  The problem cleared after about 10 minutes.

He mentioned that his K2/100 behaved the same way when first turned on and that this was known and "normal" behavior.

Is this true?  

Thanks and 73, Curt KB5JO
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Re: [K2]: K2/100 Frequency Stability?

Don Wilhelm
Curt,

A lot of information can be gleaned from reading the K2 specifications
which say the VFO stability is less than 100 Hz drift typical from a
cold start at 25 degC.

That means yours is well within specification.
That also means you should let it warm up for 15 minutes or so from a
cold start.

There is a means of adjusting the thermal compensation of the K2, but it
takes a bit of experimentation, patience, and measurement.
It involves changing the 1/4 watt resistor value on the Thermistor
board. Download the PLL Upgrade instructions and look at page 4 of those
instructions.
Your K2 already has the PLL upgrade installed (I can tell from the
serial number), but the upgrade instructions is the only place where the
additional compensation adjustment is documented.
Note that the first step of the instruction is to allow the K2 to warm
up for 30 minutes.
If your K2 does not drift excessively after a warmup period, you will
not be able to improve it after the extended stability procedure.

73,
Don W3FPR

On 9/11/2017 9:13 AM, Curt wrote:
> I built K2 s/n 06424 some time ago, then added KSB2 and finally converted it to 100W a few years ago.  Usually used it for CW only, but recently moved it to main operating position and started using it on 40M LSB mornings. To my chagrin, received comment few days ago that I was off frequency, and this morning confirmed with another op that I was 50 Hz low.  The problem cleared after about 10 minutes.
>
> He mentioned that his K2/100 behaved the same way when first turned on and that this was known and "normal" behavior.
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