Oops, correction. Looks like the K3 will handle the SB-220's T-R
relay coil voltage after all. Sorry about that, my bad. You still
need to worry about the closure timing, though. I have my K3 set
to the max (20 ms) and there doesn't SEEM to be a probelm -- but
I've never actually measured how longs it takes the original Heath
frame relay to close. You really should do that.
Bill W5WVO
----- Original Message -----
From: "Bill W5WVO" <
[hidden email]>
To: "Dave G4AON" <
[hidden email]>;
<
[hidden email]>
Sent: Sunday, August 31, 2008 3:10 PM
Subject: Re: [Elecraft] Re: SB-221 for K3 need some help.
> As far as the bandswitch is concerned, a good source for them
are
> the guys who do the 6-meter conversions for SB-220s and SB221s,
> since they remove the whole bandswitch assembly. Check with Lou
at
> King Conversions (
[hidden email]). He may be able to help you
> out. Lou does a great job with his 6-meter conversions, BTW. I'm
> using one with my K3, but part of his conversion is installing a
> solid-state buffer for the T-R line, which in the unmodified
> SB-220 switches 120VDC. Do NOT connect an unmodified SB-220's
T-R
> switch line directly to the K3's T-R switch output jack. Your K3
> will NOT be happy.
>
> Bill W5WVO
>
>
> ----- Original Message -----
> From: "Dave G4AON" <
[hidden email]>
> To: <
[hidden email]>
> Sent: Saturday, August 30, 2008 11:50 PM
> Subject: [Elecraft] Re: SB-221 for K3 need some help.
>
>
> > Don, there isn't a diode across the relay coil in an SB220 -
so
> there
> > may be a nasty back emf voltage on key release. Also, the K3
> maximum
> > keying delay is 20 mS, will the relay in a SB220 switch in
that
> time?
> >
> > I don't want to dampen your enthusiasm, but old linears were
> designed
> > for relay contact switching and generally were slow on change
> over...
> > They can be modified, but in standard format may not work too
> well.
> >
> > 73 Dave, G4AON
> > K3/100 #80, Acom 1000
> > --------------------------------
> >
> > I found out this week that K3 is good with Heathkit
> > SB-220 amps, all you need to do is connect a shielded
> > RCA cable between the units - how easy is that? !!!
> > _______________________________________________
> > Elecraft mailing list
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