[BC] Audio "proofs"

[RichardBJohnson at comcast.net]

I do! Every station for which I worked would contract Cambridge Crystals for their monthly frequency measurement --even WCHA in Chambersburg, PA! I visited him once and he showed me how he would zero-beat a signal with a local generator, and with an interpolation oscillator, measure the local generator's frequency to within one-tenth of a cycle (in those days, before Hz).

He used a general purpose receiver made by Hammarlund and a tuned loop to do the actual reception. The station was zero-beat using the S-meter. Actually, distant stations could not be zero beat because of changing propagation. The local signal generator was tuned so that the slow beat on each side of the frequency was the same as it went through zero. Cheney's skills could detect ana measure your signal even when there was on-channel interference!

I heard that before the place was closed, they went to actual frequency counters and a "Panadaptor" receiver display, but the same basic idea of synchronizing a local signal generator to your carrier was used even then.

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

----- Original Message -----
From: "Rene Tetro" <rene at wfil.com>

Speaking of measurements, how many of you remember talking to Clarence
Cheney at Cambridge Crystals each month to get your frequency measured? I
remember that he would call sometime after midnight, I would put the station
on high power,