[ARC5] Selector Relay for ARC-5 Transmitter - some info.

[Jack Antonio]

On 10/13/2013 6:07 AM, Joel R Roberts wrote:
>According to
> one of the articles I have to reference, the audio output to the
> headphones should come from pin 4 on the front adapter, however reading
> the schematics for the R-26, there is no connection to pin four. Which
> pin should have the audio output? Thanks for your help everyone....Joel
> KB0FPT.


In the R-25, R-26 and R-27, there is no connection to pin 4, audio
output is not brought out to the front. Audio is brought to pin 4 only 
on the R-23 and R-24.  This was done to support an early ILS system that
was not widely used. The R-23 and R-24 are referred to in the manual
as "Navigation" receivers, the R-25,-26, and -27 are referred to
as "Communication" receivers.

In the Communication receivers, C-15 is the cathode bypass for the 
output stage.  In the Navigation receivers,
C-15 has its ground side lifted and fed to pin 4 of the front adapter
plug.  This makes the output stage a cathode follower. Whether this
audio could drive a headset, I don't know.

Jack Antonio WA7DIA/4