[R-390] Carrier Meter adjustment

[windy10605@juno.com]

The Carrier Meter is a little sensitive to adjustment and I guess
that is why some people suggest that it be replaced with a 10 turn 
potentiometer ...or maybe it's burnt/worn because the majority of 
the current does not go through the 22 ohm, 1 watt resistor leg, it 
goes through the much less than 22 ohm setting of the potentiometer. 
My carrier meter is adjusted when the pot is at about 10 ohms 
...not much on a 100 ohm pot range.

If you look at the circuit, the 22 ohm resistor and 100 ohm pot 
are part of the cathode resistance circuit for the 4th IF and I
believe the 100 ohm pot was intended as a voltage divider for the 
meter. The way it's shown in the schematic it will affect the cathode
resistance some as you vary the "adjusted pot" value ....and it 
makes adjustment very sensitive.

If you move the green/blue wire to the center tap and remove the 
wire short from the center tap to one end, you have essentially
made the pot a voltage divider for the meter and the cathode 
resistance stays fixed at about 19 ohms (parallel 22 ohm and 100 
ohm). Seems to work fine and the pot is much easier to adjust.

Haven't found a down side yet.

73  Kees K5BCQ