[Elecraft] K3 with a Kenwood TL-922A

[Fred Townsend]

Please see comments below.

-----Original Message-----
From: elecraft-bounces at mailman.qth.net
[mailto:elecraft-bounces at mailman.qth.net] On Behalf Of Vic K2VCO
Sent: Saturday, September 03, 2011 11:51 AM
To: elecraft at mailman.qth.net
Subject: Re: [Elecraft] K3 with a Kenwood TL-922A

Actually, I believe that the K3's amp keying output could handle the +120v
key line of the
922 with no trouble. My TL922 came with a diode across the t/r relay, by the
way.

BUT -- there is a much bigger problem with the TL-922. That is that the
relay is very, very slow. You would probably have to increase the TX Delay
of the K3 to prevent hot-switching, and increasing it beyond 12-15 ms messes
up your keying. Buffers and soft-keys CANNOT fix this problem.

Vic: Do you realize that placing a diode across the T/R relay slows it down?
If you are going to quickly swing the relay you are better off to shunt the
key line with a transient absorbing device like a transorb.  As the name
infers that's a zener that especially designed to absorb transients. That
will speed the decay of the relay field rather than delaying it. The type
transorb used must be selected to have a sustaining voltage greater than
normal key line voltage. You want the transorb to only conduct during the
transient period.

73
de Fred, AE6QL