[Icom] IC 746 Relay

[George, W5YR]

Tom, I do not know for sure about the 746, but the 756PRO uses a reed relay
that is rated at no more than 16 volts open circuit and 200 ma. keying
current.

Since it is a small reed relay, the contacts are small, closely spaced, and
easily damaged by either over=current or over-voltage.

I regret that from your description it sounds as if the relay contacts have
gotten welded together and are providing a permanent short circuit across
the Key line to the amps.

Some have had some success removing the cover and finding the relay and
lightly rapping the case to free the contacts. I have no idea where it is
located, but if you have a service manual, you should be able to find it.

Lacking that approach, a trip to the shop or a do-it-yourself replacement
is probably on the horizon. I have also heard that Icom may not honor such
a repair as a warranty job because the relay ratings were intentionally
exceeded.

Some folks have described using an intermediate small relay keyed by the
Icom which in turn keys the amp(s). This will take the load off the ICom
relay, but it may change the timing of the system such that the amps are
hot-switched, etc.

In defense of Icom, their relay will safely switch *their* amps but
problems like yours are not helped by that, are they?

72/73/oo, George W5YR - the Yellow Rose of Texas         
Fairview, TX 30 mi NE of Dallas in Collin county EM13qe   
Amateur Radio W5YR, in the 56th year and it just keeps getting better!
QRP-L 1373 NETXQRP 6 SOC 262 COG 8 FPQRP 404 TEN-X 11771
Icom IC-756PRO #02121  Kachina #91900556  IC-765 #02437

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Tom Johnson wrote:
> 
> I just got a new standard IC 746, after using Drake gear for over 30 years.
> I key both an Alpha 76 and a 6 meter SB 200 by way of an old Ameco PT
> preamp, and for years, this has worked fine. It is necessary to go this way
> due the 100+ volts that the SB200 uses in its keying line.
> 
> Now, with the 746, I find that as soon as I plug the relay line from the PT
> into the 746, both amps are keyed and stay keyed. Keying the 746 changes
> nothing.
> 
> The 746 manual says not to exceed 16 volts in the keying circuit, so
> something like this will have to be in the circuit if either of the amps is
> to be used.
> 
> Has anyone else run into such a situation, and how has it been corrected?
>