Luc,
Those RF voltages look normal until one reaches the Q5 collector.
Changing R11 to 4.7 ohms (as in the power mod) will likely help, and you
can increase R30 to 33 ohms (the remainder of the power mod) if changing
R11 does not help enough.
I am concerned because you indicated only 0.2 watts output on 20 meters
- with 10.7 volts on the collector of Q6 you should have more output
than 0.2 watts unless you also have a problem in the low pass filter
area - check the number of turns on the toroids and check the values of
C46, C47 and C54. Too many toroid turns can reduce the cutoff frequency
of the 20 meter lowpass filter down into the 20 meter band and absorb a
lot of the signal. When counting toroid turns, count each pass of the
wire through the center of the core as 1 turn.
73,
Don W3FPR
luc Favre wrote:
Don,
Thanks for your quick reply. Following values are Vrms made with Elecraft RF
Probe and DDM.
(7 MHz value/14 MHz value)
Q1 gate : 0.17 / 0.16
Q1 Source : 0.11 / 0.18
Q4 base : 0.10 / 0.18
Q5 base : 0.9 / 1.1
Q5 collector : 4.7 / 6.0
Q6 base : 1.3 / 1.2
Q6 collector : 8.9 / 10.7
I suppose these values are quite consistent.
Q5 collector values and Q6 base values seem to have the same relation
betwenn them as the impedances (1:3). Am I right ?
Thanks for your help.
73
Luc/F6HJO/HB9ABB
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