[MRCA] Looking for BC-AL-430 Transmittter Info and Related Items

[Michael]

-----Original Message-----
From: MRCA [mailto:mrca-bounces at mailman.qth.net] On Behalf Of Jack Antonio
> VT-25s are not cheap, but can be had, but the VT-52s are stratospheric in
prices, when you 
> can find them.

For my good BC-A*-430, I want to use VT-52s.  (I have the VT-25s.)  It's
only for demo use with the original glass so they don't have to be real
good, they just have to kinda sorta work ... more or less.

> All bias voltages in the transmitter are developed from the grid of the PA
stage, and the 
> 6AQ5 oscillator develops much more bias voltage than the original tube.
So, I had to shunt 
> some resistance to lower the bias voltages down to allow enough plate
current to flow.
> I'll dig up the details and let you know what I did.

I'd like to know as well, if you please.

> I am trying to find the time to try some other tubes like maybe some 6V6,
6Y6 or similar 
> tubes.

Something I've been eyeing for the same purpose is some of the Russian Cold
War leftovers.  There is a submini pentode - the 6P30B - that has a 5.5w
plate dissipation that should work nicely triode connected with 150v or so
B+.  There are a few other tubes but that one got my attention for another
application. 

> Another problem is that the can type capacitors are starting to show
problems, like leakage 
> (both electrical and oil), and need to be bypassed, or rebuilt. This
applies to both the tx and 
> rx.

Oooh, thanks for this.  I'll give mine a good once or twice over.

> The SCR-183(283) (BC-229(429))receiver does not have a BFO, so is limited
to voice and 
> MCW, 

A BC-183 Freq meter/signal generator/BFO works wonders for that lack.  (A
BC-221 or LM can manage in a pinch.)  This is apparently how it was supposed
to work in the liaison installation in the XB-15.

> but the tx control box does have a key jack, built in key, and mode switch
for Voice, CW 
> and MCW.

Yeah, but what's the Mic jack for?  Never did figure that out.  :-D

Best Regards,
 
Michael, K3MXO, CBLA #6, BL01hx15np24 ... or there abouts  
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