On Fri, 19 Aug 2011 12:59:57 -0700, "Sal" wrote:


"Jeff Liebermann" wrote in message
.. .

snip

Mini-rant: Why do almost ALL commerical radios have tx timeout
timers, while almost ALL ham radios don't have this feature?

Is it because we're all known to be gasbags?

Yes. That's also why many Japanese ham radios are severely lacking in
microphone gain. I guess they assume that all Americans are always
yelling.

Timeout? Why the very *impudence* of that radio!!!

Ok, bad choice of a name for the timer. Perhaps "anti-ratchet mouth"
or "monolog restrictor" might be better.

All kidding aside, we had a major repeater outage in San Diego some years
ago. A 50w mobile, in the middle of a hotel parking lot, was on the air for
hours, holdng the repeater. The T-hunters who found the car ID'ed the owner
by his callsign plate and contacted him in the hotel. It was the old
microphone-between-the-seat-cushions trick. Timeout would have helped that
day.

Yep. It's all too common. My guess is one every month or so.
Unfortunately, I managed to jam the microphone under the debris pile
that usually clutters the passenger seat, jamming the local repeater.
I was easily identified by the classical music in the background since
nobody else around listens to classical music. What's really
irritating are the number of packet radios that end up on repeater
frequencies. Usually, we can decode the call sign and contact the
culprit. Occasionally, there's no call sign as the owner is trying to
setup his TNC. There's also the stuck transmitter on commercial and
public safety frequencies. Those are fun and gets us plenty of points
from the various agencies. Extra credit to the local comm shop that
likes to defeat the timeout timer, for no obvious reason.

My favorite stuck transmitter was on marine channel 16. There was a
very strong carrier on Ch 16, that could be heard all over Monterey
Bay. Everyone dug out their DF hardware and the searching began.
Strong signal, no modulation, 100% duty cycle. This should be easy.
Right...

After 5 days of bad guesses and dead ends, the culprit turned out to
be a marine base station on Fremont Pk (3,000ft). It was rarely used
and was only functional in order to maintain the license. Something
went wrong with the DC wireline control system (with no timer) which
stuck it on the air. Why so difficult? The strong signal created a
wide assortment of reflections. Everyone had trouble separating the
strong reflections from the incident signal with the Doppler DF boxes.
I was using my rotating antenna kludge, but stupidly used a 5 element
yagi tuned to 146Mhz. At 156.8Mhz, I later discovered that it had
almost as much gain towards the back of the antenna as it did in the
forward direction.

Incidentally, there's another difference between ham and commercial
mobiles. Commercial mobiles have a PL hang up function, where the
receiver is in PL decode when the mic is hung in the hanger, and goes
to carrier squelch when removed. Many ham mobiles seem to be missing
this useful feature.


--
Jeff Liebermann
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558