[Elecraft] Problem for K2 # 4498

[Don Wilhelm]

Bob,

I was on vacation, but I did not see any answer on the reflector.
Several questions:
Is this a K2/100 or a QRP K2?
Does the problem appear on all bands?
Which filter are you referring to - the bandpass filter or the Low Pass
filter?
Does the 450 kHz 'modulation' appear at the Transmit mixer inputs? Which one
(BFO or VCO)?
Do you have adequate oscillator injection levels (RF voltages) at the
transmit mixer?  See the manual Appendix E, page 10 and following for proper
levels as measured with the RF Probe.
What is the RF Voltage at the Transmit Mixer output when the power control
is set to 5 watts?
What is the RF Voltage at the Buffer output when set to 5 watts?
Compare the latter 2 RF voltages with the expected values shown in the
manual Appendox E page 14.
Have you done the DC voltage checks?  Do they compare within 10% of the DC
Voltage chart?

73,
Don W3FPR

> -----Original Message-----
>
> Hello the list !
> I'm calling "Au Secour" after a problem that I tried to solve without
> results.
> With power down to zero, on all bands, there is no output BUT I get a
> very healthy signal at about 450 khz up to the firlter input. When I
> start to increase power, up to about 7 to 8 watts, the output signal
> is shopped by this 450 khz "carrier", and when the power can be pushed
> over 10 w the 450 khz disapear completly. (On 1.8 output max is 0.2 w,
> 3.5 5 w, 7 12 w 10.1 8 w, 14 10w, 21 7 w, 24 6 w, 28 5.5 w. All
> transistors where changed ( 2N5109, 2SC2166, 2x2sc1969)without results
> so...
> Does anybody had this situation ?
>
> Thank you in advabce
> F5UL/Bob