[AMRadio] BTA Mods


KC8OPP Roger S. kc8opp at yahoo.com
Sat May 27 16:47:34 EDT 2006


Rick,

Just a thought on the osc circuit.  You could always
disconnect the osc board and use a signal generator to
feed the grid of the 6146.  This will let you test out
the remainder of the transmitter on the AM broadcast
freq.

I would think that the crystal osc will be removed
when you move it to 75M, so fixing it may not be worth
the effort.  

73's
Roger
KC8OPP

--- Rick Brashear <rickbras at airmail.net> wrote:

> 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
> 
> 
> 
> 
>
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