[Heathkit] Mohican BFO question, other things.

[Philip Atchley]

Hi,

In working on this Mohican and going through it thoroughly I've found an 
anomaly in the BFO circuit (varactor tuned).

1.  The schematic (BAMA download) shows resistor R91, 1.5K between the 
low side of the Pot and ground.  On this set the low side of the Pot 
goes directly to ground, no R91.  Was this a design change or did 
somebody do it themselves, perhaps to get additional BFO range?  The 
problem I have with it is this allows the Varactor to have "Zero" bias 
on it, and it could then act as a "rectifier" of the generated signal 
Voltage, instead of a capacitor as it's supposed to be.  It just doesn't 
seem "right".

2.  The tuning of the antenna coils/trimmers, antenna tune control seems 
to have very little response.  The RF amplifier is now working after 
replacing it's RF amplifier, but the tuning is non critical/almost non 
existent.  Is this a very "Low Q" circuit and just not responsive or 
should I be looking for a problem component/wiring?

73 de Phil,  KO6BB
991 Different NDB's heard to date.

http://www.geocities.com/ko6bb/
Merced, Central California, 37.3N  120.48W  CM97sh