[GreenKeys] Is There A Vacuum Tube Schematic?

[Roy Morgan]

On Nov 16, 2009, at 1:42 AM, Randy and Sherry Guttery wrote:

> PATRICK KELLY wrote:
>> Is there a vacuum tube schematic for the circuit to connect a  
>> serial ported pc to a teletype machine of any make of model? Is  
>> there a way to derive such a schematic?
> The output stage(s) of the URA-8 converter could be used...  shifting
> from +/-3V to enough voltage to drive the 6AQ5s would likely take
> another gain stage, but shouldn't be very difficult to put together...

Patrick,

The URA-8 includes the tone demodulator/loop-keyer CV-89, which is the  
thing Randy is suggesting you look at.  The basic tube lineup you are  
interested in is: 1/2 12AX7 amplifier to 1/2 12AU7 keyer that drives  
(through a neon lamp type 991) the grids of the two paralleled 6AQ5's.

There are somewhat less common dual triode tubes that combine high and  
low mu sections in one tube, and there are other tubes (such as sweep  
tubes) that would handily substitute for the two parallel 6AQ5's.   
Quite possibly there's a compactron that would have all three in one  
envelope!

I have a somewhat poor digital copy of the schematic in case you have  
not found it yet - glad to email the files to you.

Roy


Roy Morgan
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Groton NY, 13073
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