Ilya,
I am sorry you are having problems with the PLL Reference Oscillator.
Yes, there have been several reports of this same failure.
First try a small value capacitor (10 to 15pF) from the source of Q19 to
ground.
If that does not correct it, can you obtain a J310 FET locally? If so,
replace Q19 with it.
The problem seems to be that the J310 FETs in thru-hole format are fast
disappearing from the market, and the last batch purchased by Elecraft
does not operate well at the high frequency end of the PLL Reference
Oscillator.
I am currently testing the J309 as a possible replacement. The testing
should be completed in the next few days.
One ham with a similar problem wired an SMD J310 on the bottom of the
board with good results - if you cannot find a thru-hole J310, you might
consider that solution.
73,
Don W3FPR
On 8/27/2018 4:47 AM, Ilya wrote:
Hi Gentlemen!
I'm in progress of assembling my first K2 #7837 and now I'm stuck with PLL
reference oscillator test. Seems that I've already read all previous email
threads regarding similar problems all over the internet - and nothing
helped.
When I just turn on my K2 after some time it's been off - I'm getting the
following figures in PLL reference test (TP3):
- Band + is 12099.1 khz
- Band - is 12086.15 khz
After some time (just a minute or so), the BAND+ value starts drifting
down. Drifting slows down with time, but in 2-3 minutes I'm getting 12070
or smth like that. If I touch RIT/XIT knob - the value drops even lower -
to 12055 or about that.
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