[Icom] More on isolation relay with non-ICOM amps

[Adam Farson]

Hi Larry,

Please refer also to Larry W0QE's posting on this topic.

I shall be looking out for the scan.

<< What about the typical contester sending at 35 - 40
wpm with a relay rated for 10 wpm, or am I missing
something? >>

I think you may have missed the thrust of my previous posting. The relay
manufacturer did not rate the relay for 10 wpm. As I mentioned, our
component engineers tested reed relays at 1200 ops/min (equivalent to 40
wpm, or 4 times the OMR-109F spec), without observable degradation. The
contact load for these tests was 50 ~ 100mA at 50V - far higher than the 5mA
at 12V which I suggested to maximise contact life.

<< Does this suggest that Alpha Power is incorrect in their diagnosis of the
cause of relay failure? >>

With infinite respect where it is due, Alpha/Crosslink are an amplifier
manufacturer, not a relay manufacturer.


<< Apparently, the safest course of action is to use a buffer circuit with
any rig and an amp of a different manufacturer. >>

I agree that this is the most prudent course. However, I would remark that I
have been using solid-state amplifiers - first an IC-2KL, now a Yaesu
Quadra - for a total of 14 years, without a buffer circuit. The reed relay
has never failed in any of my exciters.

Both amplifiers present a TTL-level keying load (5V at a few mA) to the
exciter. If the amplifier presents a 12V/7mA load, as do the current Alphas,
a buffer should not be necessary. As Larry W0QE stated, "as long as you
don't weld the contacts by exceeding their rating, [small reed relays] are
often good
for a billion operations.   The manufacturers regularly will guarantee
several hundred million operations if you are a really big customer. Don't
worry about it."

I am confident that the relay vendors are more than willing to extend such a
guarantee to Icom Inc.