[ARC5] Differences: plain models vs "B" models.

[Jack Antonio]

On 5/7/2014 12:08 PM, Kenneth G. Gordon wrote:
> I have been asked what the differences are between the plain models and the
> "B" models of the BC-45* receivers.

The -B models have the low impedance output tap on the
output transformer.

> I had never thought about this before, but now I am curious: I suspect that the
> difference is in an AGC or at least a better AGC circuit than the plain models.
> Anyone care to comment?

The "AVC" (or lack thereof) is the same in both -A and -B.

Actually there is a form of AVC in the -274N receivers, but the voltage
is developed across the 100K resistor in the grid circuit of the last
IF. It is not developed by the 12SR7 diodes.

What I am curious about, is the BC-456E modulator. I have an 
installation/operation manual which references the E model, but does not 
explain the difference is. The associated maintenance manual, does
not reference the E model at all.

As in the receivers, the difference between the BC-456A and B is the
addition of the low impedance output tap for sidetone.

Jack Antonio WA7DIA/4