[BC] Frequency Measuring

[WFIFeng@aol.com]

In a message dated 03/20/2007 05:30:52 PM Eastern Standard Time, 
tosenkowsky at prodigy.net writes:

> As I was driving towards the station, I heard the "tone". I
>  figured it was the Cubans. When Clarence called he had me
>  play the cart several times. This was unusual. He then asked
>  if I did any work on the transmitter. We were +420 Hz! That
>  was the tone! He explained that the old freq meters would go
>  to zero on overtones (above 40 Hz, I believe). So indeed he
>  was able to receive a 5kW 1380 KHz Naugatuck, CT station
>  in Mass.

That's quite the "tone", alright! ;)

When we first got our new transmitter, the *only* thing I didn't think to 
check was the frequency. Since everything was fine getting it on the air, we we
re 
just humming along every day for about a week. One Saturday morning, our 
Part-Timer got a call. It was the FCC, Belfast Maine monitoring station. I came
 
down to the station and fired-up our old TX into the dummy load. (I knew it was
 
very close to 5Hz high.) Using the FIM in just the right place, I could 
clearly see the heterodyne when I got the new TX closer to the old. I got them 
as 
close to zero-beat as I could.

The following Monday, I called the phone number the guy left with our PT'er. 
I told him who I was, and that i had made the adjustment later that same day. 
He said, "Hold on a second. OK, looks good."

We were 23Hz off freq.

Normally, I keep us running about 5Hz above WTWP. Why? The low freq flutter 
is far less annoying than a gradual zero-beat. It's quick enough that most AGC 
circuits aren't too bothered by it, and it's low enough that most receivers 
won't reproduce it.

Willie...





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