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

[David Stinson]

----- Original Message ----- 
From: "Hubert Miller" <Kargo_cult at msn.com>

> The only TR switch is the key, so you close the key to receive, 
> yes?

No, the fragment of the manual we have has
 an earlier itteration of the set.
The one I have here matches a later update.
The diagram is at:
https://goo.gl/photos/DycqNJdQ24aC2afF7

In receive, R5, 100K, is in the plate lead.
The stage draws 0.5mA, dropping 50V
and applying 70V to the plate.  This enables
a lower-level oscillation for regenerative detection.
When you press the key, the meter and R5
are bypassed and full 120 Volts is applied
to the plate shunt feed for the "TX Level"
oscillation.