Topband: Loud clicks -- Hot Switching

[john.devoldere, ON4UN]

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 at contesting.com [mailto:topband-bounces at contesting.com]
On Behalf Of GEORGE WALLNER
Sent: Saturday, January 02, 2010 8:51 PM
To: topband at 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
_______________________________________________
"160-meters is a band for men, not for sissies!" - SM5EDX

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