[BC] AM Modulation Monitor Off Air Monitoring

[RichardBJohnson at comcast.net]

You need about a watt of RF to run a monitor. In the "olden days," we would build a TRF "tuned RF" amplifier with a carefully shielded front-end, that would amplify about a milivolt from an outside random-wire antenna to the required 7 to 10 VRMS needed for the monitor. It needed to be linear, and could not use AGC, which would introduce apparent carrier-shift with asymmetrical modulation.

Since some monitors do not care about the input frequency, one could amplify the 455 kHz IF of a conventional superheterodyne receiver using the same kind of linear amplifier. There should be some used RF amplifiers around that were designed for this purpose, even though you might have to put in new electrolytics and re-tube it with Russian components.

Cheers,
Richard B. Johnson
Book: http://www.AbominableFirebug.com/

----- Original Message -----
From: "Peter Deal" <petedeal1 at yahoo.com>

I have a spare Belar AM modulation monitor.