Les,
I have built amplifier keying interfaces for all my Icom contesting radios
(IC-275, 375, 475, 575, 910H, etc) using the ACC jack on the rear. All of
these radios have been used at one time or another to drive KW amps and here is
the approach I have used.
Purchase an 8 pin (or even 7 pin) DIN plug that mates with the 910H ACC
socket. Wire pins 3 (Send) and 7 (13.8V) to the coil of a small SPST 12 volt
relay. Use a relay with contacts capable of switching whatever voltage and
current the amplifier keying line is. I use a small Potter Brumfield series
relay.
Solder a diode (1N4004) across the relay coil (cathode to the 13.8 V) to
prevent voltage kickback into the 910H.
The "Send" signal of the ACC jack on the rear of the Icoms is actually the
internal PTT buss. The description in the Icom manuals is somewhat misleading.
Besides grounding this signal to put the radio into transmit, you can also use
the signal as a low level PTT control line to drive a relay to key an external
amp or other device.
Ron
WW8RR
To: VHF Contesting Reflector; IC910H@yahoogroups.com; vhf@w6yx.stanford.edu
Subject: [VHFcontesting] Interfacing an IC-910H with TE Systems Amp
At the risk of enduring public ridicule, I'm going to confess to being
completely ignorant of the ways of amplifiers. In my ham radio career of nearly
40 years, I've never once ran an amplifier of any kind until now.
But I recently purchased a TE Systems 1412G to give me more punch on 2 Meters
for weak signal and WSJT work. I will be using this amp with an Icom IC-910H.
Many have pointed out the dangers of keying the amp via RF switching, and
suggested that I key the amp directly using the PTT line of the radio.
Most HF radios that I own have jacks on the rear (ALC) that are dedicated to
this purpose. The IC-910H lacks this, and I assume that I'll need to use the
ACC jack? But frankly, after reading the manual, and re-reading it, I'm stumped.
Can someone who has used this specific rig with outboard amps please provide
information on how to best accomplish this? As always, I'm indebted to the
members of these groups who have really helped get me started in V/U. All
replies are read, printed out, and placed into folders that I refer to often.
The advice has literally been invaluable. I'm very grateful!
73,
Les Rayburn, N1LF
Les Rayburn, director
High Noon Film
100 Centerview Drive Suite 111
Birmingham, AL 35216-3748
205.824.8930
205.824.8960 fax
205.253.4867 cell
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