[BC] Frequency Measurements and 1000 Hz tone...

[Burt I. Weiner]

Tom,

I've been making off-air frequency measurements for close to 40 
years.  During that time I've had several clients that were on the 
same frequency, 1 KW or lower and more than 100 miles away.  Two that 
come to mind are on 1340 - a very crowded piece of spectrum.

What I have them do is in the middle of the night, separately, put a 
1000 Hz tone on from a cart.  This has become more difficult to get 
done as time has gone on because neither one of them has a sign off 
or middle of the night routine maintenance schedule and are 
automated.  That aside, with the 1000 Hz tone it is much easier to 
zero beat the carrier.  As you approach zero beat (with the transfer 
oscillator) you will hear the beat in your receiver and as you 
approach zero you will easily hear the beat in the 1000 Hz tone get 
slower until it stands still.  There's no issue in accidentally zero 
beating one of the sidebands because, first of all, they are 1000 Hz 
away from the carrier and if you want you can zero beat each one 
independently to be sure.  Once you've reached exact zero beat it's a 
simple matter of measuring the transfer oscillator with a counter.

I hope that answers your question but if you want a further or deeper 
explanation, let me know.

Burt

At 02:18 PM 3/20/2007, you wrote:
>Subject: [BC] Frequency Measuring
>To: broadcast at radiolists.net
>Message-ID: <3.0.6.16.20070320130158.28579438 at mail.box311.net>
>Content-Type: text/plain; charset="us-ascii"
>
>During my very limited experience in broadcasting back in the
>sixties, the station I worked for in central Pennsylvania
>used a person in Massachusetts to measure the frequency.
>
>I always wondered how he could hear the station well enough
>to make the measurement?
>
>The station was on 920 kHz with five hundred watts
>directional at night and one thousand watts nondirectional
>during the day.  When the station went off the air at
>midnight he would call and we would put the transmitter back
>on with the one thousand watt nondirectional signal with a
>one thousand cycle tone and he'd give the frequency measurement.
>
>How in the world did he do this?
>
>Tom

Burt I. Weiner Associates
Broadcast Technical Services
Glendale, California  U.S.A.
biwa at earthlink.net
K6OQK