[Elecraft] TP2

[W3FPR - Don Wilhelm]

Peter,

My guess is that there is a bad solder connection somewhere in the BFO area. 
The fact that things stabilize when you touch something in the area strongly 
suggests something wrong with the soldering.

Pressing BAND+, BAND- when in CAL FCTR should swing the voltage between 0 
and 8 volts, so it seems things are likely OK with the control voltage.

The only other thing I can think of which would cause similar behavior is a 
weak crystal.  If you suspect the crystals, try removing one of them and see 
if the behavior stabilizes (the BFO range will become more narrow - so that 
is only for a test, not a cure).  2 parallel crystals are used to 'de-Q' the 
crystals and provide a greater BFO range than one alone would provide.

73,
Don W3FPR

----- Original Message ----- 

> Some ask for more info.
>
> With the probe in TP2 and CALL on FCTR the reading jumps fast around 4.620 
> mc
> Then the voltage on RP6 is stable reading 6,48V
>
> Pressing BAND -
> The readout is 4,917 mc and stable but the voltage on RP6 has jumped to 
> 8,0V
>
>>
>> I have a K2 rig here for repair and this baby has a instable frequentie 
>> reading on TP2
>> After touching a part of the bfo its solid (4,917 mc)
>> Q24 is working good, but on  U11 (bfo) pin 6 and 7 are 1 volt too low.
>> I a have all ready replace D37 and D38 bun no effect.
>>
>> Question. Why are there 2 cristals? (X3 and X4)
>> The low voltage on  pin6 and 7 of U11 is this caused by a defect IC or 
>> something else?
>>
>> Peter
>> PC2A
>>
>
>
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