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

[W3UIO]

The following references the Alpha Power web site
which in turn references another site posted on this
list recently. Apparently the problem with the ICOM
send relay is not related to voltage/current but to
the number of operations per minute that it will
sustain. This url indicates that CW operation above 10
wpm will exceed the relay specs.

This also explains why some have used non-ICOM amps
without a buffer or isolation relay and have not
experienced problems.

http://www.alpha-amps.com/html/icom.htm

"IC-756 and IC-746 family:
The Alpha 99 / 91B has 25vdc @ 7ma at the RELAY jack.
This is within the specs of 
the OMR-109 relay in the Icom radios (60v/500ma),
although Icom says it is rated for 16v/500ma.
The problem is not the voltage rating, but the spec of
the relay for operations per minute.
With NO electrical load on the contacts, it is rated
for 300 operations per minute,
or about 10 wpm QSK CW. Faster than this will cause it
to fail prematurely." -- Alpha Power

A simple schematic which does not require its own
power source will be posted here either by me or by
Dave (AA6YQ) as soon as I get it scanned or get a copy
to Dave for scanning. The circuit is from ICOM
Technical Service and contains one transistor, one 1 K
resistor, and one 1N4002 diode. This transistor will
key the amp.

Larry, W3UIO


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