Hi to all:
I never ever transmit on the air without having an oscilloscope in line
where I can see the shape of my transmitted signal. Hot switching looks
terrible, it not only sounds terrible. Recently I was called on 160 by a
W-station that sounded like a British M-station. I have heard JA's that
sound like OA's etc. Often all of the first dot is used only to create a
terrible click.
A second hand 20 MHz scope should not cost more than max 200$, and prevent
bad signals, ruined amplifiers and bad temper. Please let's all get a scope
and monitor our signals. It's a question of ethics.
73
John, ON4UN
-----Original Message-----
From: topband-bounces@contesting.com [mailto:topband-bounces@contesting.com]
On Behalf Of GEORGE WALLNER
Sent: Saturday, January 02, 2010 8:51 PM
To: topband@contesting.com
Subject: Re: Topband: Loud clicks -- Hot Switching
G'day TopBanders,
Hot switching -- or delayed PA RX/TX switching -- is a far
more common problem than is generally realized.
During a recent DXpedition I heard a lot of stations and a
significant percentage of them had some problem with their
PA RX/TX switch. At the RX end problem manifests itself in
the truncation or omission of the first dot of the
call-sing's leading character. After a while you learn
that OA1xxx is really JA1xxx, M0xx is really W0xx, NA3xx
is really RA3xx, and so on. Many of them probably had T/R
switching problems. (There have been some claims that the
AGC of the K3 can cause the leading leading dot become
inaudible. Maybe so, but I heard the same phenomena on an
Icom 746, which has a conventional AGC.)
The problem is hard to detect by listening to one's own
signal. From close up 100W sounds the same as 1000W. I
recommend that if you use an amplifier, you should check
your signal with an oscilloscope.
George, AA7JV
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"160-meters is a band for men, not for sissies!" - SM5EDX
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