I would be careful about running DC through the coax. Rapid rise and fall
times of the DC voltage can generate RF spikes, and the collapse of the field
in a DC relay if there is one at the business end can produce high
instantaneous voltages back down to the rig end of the feedline.
There are diode and capacitor-based circuit protections that can prevent this,
but those phenomena were the prime suspects for why a remote antenna switch
using DC inserted into the coax blew away the PA transistors and associated
circuitry three times in a K2, until I trashed the switch. I can’t describe
exactly what the protection circuits are, though as I recall they are pretty
simple. Should be something in the archives about it from a couple of years
ago.
Ted, KN1CBR
------------------------------
Message: 23
Date: Wed, 15 Nov 2017 10:42:19 -0800
From: Steve Sergeant <[email protected]>
To: [email protected]
Subject: Re: [Elecraft] Using T1 with KX2 or KX3
Message-ID: <[email protected]>
Content-Type: text/plain; charset=utf-8
Hmmm. That means that it should be trivial to make a DC-blocking circuit
that would allow you to pull the ring of J3 to DC (and not RF) ground
over the coax to initiate tuning. Then you would have part of the remote
control puzzle solved.
That's nearly enough to finally get me to buy a T1.
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