[Elecraft] PBSK31

[Don Wilhelm]

Phil,

I cannot say if David did anything special for frequency stability, but 
any K2 above SN 3000 had the BFO stability mod and the PLL Temperature 
compensation mod installed which can achieve the necessary stability.  
K2s below SN 3000 can be upgraded with those upgrade kits.

The stock PLL Temperature Stability Mod has resistor RA as a 33k 
resistor.  That resistor value can be modified to achieve closer 
temperature stability for any particular K2.  The K2 manual does not 
contain information about how to vary and check the compensation, but 
that information is contained in the instructions for the PLL 
Temperature Stability Mod - download from Elecraft.

The temperature change in the K2/10 is not likely to be very much even 
for long periods of transmit because the PA transistors and heatsink are 
not close to the VFO/PLL and BFO areas and there is a lot of 'air space' 
inside the enclosure.
With the KPA100 added, that air space is much more confined and the heat 
from the KPA100 PA transistors will have an influence.
In other words, while the stock K2/10 may be sufficiently stable, the 
K2/100 may need some 'tweaking' of the RA resistor value for equivalent 
stability.

73,
Don W3FPR

On 4/24/2016 6:23 PM, Phil Wheeler wrote:
> David,
>
> Do you do anything special to ensure frequency stability in those 
> modes with your K2?
>
> Phil W7OX
>
> On 4/24/16 3:02 PM, David Giles wrote:
>> I've made hundreds of contacts using JT65 and JT9 with my K2 at 5W. 
>> Most of these portable on a 12v battery with solar charging. With a 
>> 48 second transmit period, it's probably more of a stress test than 
>> BPSK31.
>>
>> 73 de David VK5DG / VK3TUN