[VHFcontesting] Interfacing an IC-910H with TE Systems Amp

[Rogers, Ron]

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 at yahoogroups.com; vhf at 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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