[Elecraft] K3 with a Kenwood TL-922A

[Fred Townsend]

Granted. The point is where time is involved do not suppress the transient
by placing a diode across the relay coil. That doesn't necessarily solve the
problem. You may need to bypass slow mechanical devices with fast electronic
devices like optical isolators for break-in operation.
73
Fred, AE6QL
 

-----Original Message-----
From: elecraft-bounces at mailman.qth.net
[mailto:elecraft-bounces at mailman.qth.net] On Behalf Of Joe Subich, W4TV
Sent: Saturday, September 03, 2011 1:18 PM
To: elecraft at mailman.qth.net
Subject: Re: [Elecraft] K3 with a Kenwood TL-922A


 > Vic: Do you realize that placing a diode across the T/R relay slows  > it
down?

The diode only slows down the release ... the problem is the make time not
the release time.

73,

    ... Joe, W4TV

On 9/3/2011 3:38 PM, Fred Townsend wrote:
> 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
>
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