Well... I have investigated the printed circuit board on the 1R2 on
which the crystal ovens are mounted and find there have been several
modifications and/or repairs made through out this old girls life. My
intention, as advised by much more knowledgeable people on these
transmitters, is to put it back to it's original state, be sure it's
operating at the original specifications, then begin the conversion to
75 meters. My concern is that some of these mods may have been handed
down by RCA and should possibly be left in tact. Does anyone know of
any modifications that RCA issued concerning this portion of the
transmitter? I have found traces cut and spliced to other traces, a
small variable capacitor replacing a compression trimmer and two of the
three crystal sockets more or less taken out of use with that fact
marked in pencil on the board. My inclination is these are repairs made
due to failure of components, but with no documentation on the repairs
it's very difficult to be sure. The board is badly scorched beneath the
4000 ohm 10 watt resistor, but I have read this is a common issue.
There is no trace damage to the board from the heat.
Any advice will be very much appreciated. For those who subscribe to
more than one list, I apologize if you receive this post more than once,
but I want to reach the largest audience possible for assistance and advice.
Thanks,
Rick/K5IZ
- [AMRadio] BTA Mods Rick Brashear
-