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Re: [Amps] Relays

To: "Amps Amps" <>
Subject: Re: [Amps] Relays
From: "Paul Christensen" <>
Date: Mon, 31 Mar 2008 07:15:36 -0400
List-post: <">>
> spend another $30" as someone put it.  I must be on my 4th relay now (MTBF 
> =
> 2-3 years) and noticed it sticking towards the end of WPX SSB this 
> morning -
> hardly an onerous job for a QSK-rated linear I'd have thought.

Gary, one root-cause of an R.F. vacuum relay's premature demise is related 
to hot-switching.  Oftentimes, the operator doesn't know its occurring. 
About ten years ago, I downloaded a firmware upgrade to my transceiver and 
began receiving key click complaints, owing to the fact that the 
hot-switched amp was destroying the ramped CW waveform.

Since that time, I routinely monitor my CW waveform with a Tektronics SC-504 
dual-trace scope.  Just six months ago, I upgraded the firmware of another 
transceiver, only this time, I caught the hot-switching, notified the 
manufacturer and the fix was sent through the Internet.  Anyone who owns a 
flash-upgradable transceiver really needs to consider adding a station 
scope.  For CW ops, its an easy exercise to trigger the scope from an 
external keyer and conduct the same measurements as used by the ARRL to 
determine waveform rise/fall times, and the latency between the time of key 
down and the presence of R.F.   I use the second channel for monitoring the 
incoming waveform of the received station.

Paul, W9AC 

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