[ARC5] Added 6F6 audio stage.

[WA5CAB at cs.com]

The early receivers (RAT/RAT-1, RAV and ARA) , plus the AN/ARC-5, all have 
500 ohm output.  The early SCR-274-N had 4000 ohm output.  In the B models, 
the transformer has an added 250 ohm tap.

In a message dated 10/20/2012 00:02:22 AM Central Daylight Time, 
kgordon2006 at frontier.com writes: 
> Remember, the early receivers had something like 8000 ohms output instead 
> 
> of anything much lower. Then a 600 ohm tap was added to the output 
> transformer in later models.
> 

Robert & Susan Downs - Houston
wa5cab dot com (Web Store)
MVPA 9480