[Milsurplus] BC-9 Loop Test: Scratching My Head.

[Hubert Miller]

If you look at the partial manual that was posted, mentioned previously, what you are describing is the SCR-77-A, the early version. Except that they did run it at 120 volts, not 60. 
Altho no operating instructions are there for the SCR-77-A,  it's apparent the oscillator is continuously running, under receive, while for transmit, it's keyed.  The same power level
for receive and transmit, no receiver dropping  resistor. You can imagine this 
might make it difficult when more than two stations were operating and one was quite a bit weaker. This set did NOT have the frequency offset Dave's improved version exhibits. 
The dropping resistor in Dave's later BC-9 was an improvement, so-called, to decrease the radiating receiver level. That brought other problems, which maybe even are more 
difficult to overcome. But i think they "could" communicate, altho the stations would be chasing each other across the dial. 
-Hue 

-----Original Message-----
From: Milsurplus [mailto:milsurplus-bounces at mailman.qth.net] On Behalf Of Kenneth G. Gordon
Sent: Saturday, February 11, 2017 4:58 PM
To: Richard <brunneraa1p at comcast.net>
Cc: Milsurplus at mailman.qth.net
Subject: Re: [Milsurplus] BC-9 Loop Test: Scratching My Head.

On 11 Feb 2017 at 19:44, Richard wrote:

> 
> I think someone said the last change was higher voltage on transmit.  
> Some dim bulb who knew a thing or two, but not enough, probably 
> proposed it for more output, and it was accepted by a supervisor who 
> knew less.  I've seen this happen on big electrical equipment, with disastrous results.
> Richard, AA1P

Good thinking.

So, if David dropped the 120 V feed to 60 volts (which is the maximum rated plate voltage for a VT-1) then removed the capacitor and 100 K resistor, replacing them with a piece of wire, the system may work correctly?

Hmmm.....well, I don't see it. The "oscillating detector" will be oscillating at the same level of output in either case, it seems to me.

THe only thing the key would be doing is bypassing the meter and the audio stages by a bit.

David?

Ken W7EKB

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