Substitute for Ameritron ARB-74 amp interface

Donald Hellen

Though this is a "repair" forum, I thought this might also be
appropriate to post here, especially since it's not a busy place at
the moment.

I decided to put some protection between my 7300 and my amplifier, and
Ameritron 811H, for the sake of the 7300, not for the sake of the

I was reading an article by a ham here:

and wondered if this SSR (solid state relay) might do the trick (see
below). It has all the connections protected and would look a little
nicer for about the same price as the SSR he used and the other one he
If it would work, I'm just a bit confused about the interconnections.
I know the #3 and #4 terminal faces the 7300, and the #1 and #2 face
the amplifier.

Is the center conductor of [SEND] positive and the center conductor on
the Ameritron also positive? Or do I need to provide 12V (or some
other voltage) to operate the SSR through the 7300's [SEND] jack?

As I understand it, each time the amp is energized, the SEND line
needs to ground the amp's send jack.

As for the ALC line, it looks like it's just a plain RCA to RCA plug

If I understand it correctly, I can also just cut an RCA to RCE plug
cable in half and wire it to this SSR and I'll have the essentials of
an amplifier interface.

I just want to check before ordering the item. I think it will sink
more current than the Crydom DMO063 or Crydom MPDCD3. I'm not
concerned about it being bigger as it will be plenty smaller than the
ARB-704 interface.

Your thoughts?

Donald -- AD8DY
Formerly KJ3I

Some ham radio groups you may be interested in: