NC-101X S-meter circuit

[stevef]

My 101X is a 1937 eye-tube version which a previous owner converted to an S-meter.  As I've been able to determine so far, the first version of the NC-101X had the eye tube, which National soon changed to an S-meter.  In that version, the S-meter bridge was in the RF amp plate lead across a 250 resistor.   In the next version of the 101X, National added a noise limiter and moved the S-meter bridge to the 2nd IF amp plate lead across a 1000 ohm resistor.

Is it therefore "better" to have the S-meter in the IF amp circuit or the RF amp circuit?

Steve, KK7UV

[WQ9E]

Steve,

It really doesn't matter.  In either case it is reading the change in plate current due to grid bias devloped via the AGC system.  S meters aren't precision devices  in any case and because it is AGC driven it is going to respond to any signal strong enough (including interfering signals) to develop AGC voltage regardless of  whether the actual metering source is at RF or IF.