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Phil Kane · June 17th 07, 09:29 PM posted to rec.radio.amateur.moderated

On Sun, 17 Jun 2007 08:50:33 EDT, wrote:

In the bad old days, 27 MHz was an ISM band, reserved for things like
diathermy and heat-sealing machines. I remember one case, here in
Philadelphia, where a heat-sealing factory's machines put a strong
harmonic right on the Philadelphia Police dispatcher channel.

The major problem with the 27 MHz heat sealers was the 4th harmonic in
the aviation bands. The local FCC engineer in charge had the legal
authority to shut the plant down immediately without a warning or
hearing and the plant could not resume operation until it certified
by measurement and an FAA overflight that the IX was corrected. The
necessary shielding to accomplish compliance is the reason that the
characteristic "heat sealer buzz" is no longer a problem on 11 or 10
meters.

Of course FCC was all over them in a big way. But imagine if FCC had
dragged its feet...

Even today, FAA complaints take first priority, but in reality that
was a different FCC... g

In my first year with the agency we went out on about a half-dozen
such complaints in the San Francisco area, but 30 years later when I
retired we hadn't received such a complaint in many years.
--

73 de K2ASP - Phil Kane

From a Clearing in the Silicon Forest
Beaverton (Washington County) Oregon

e-mail: k2asp [at] arrl [dot] net