The "Send" signal from the output of the ACC jack (Pin 3) on the rear of the
IC-910H (or any of the Icoms) is actually the internal PTT bus logic signal. It
goes "low" anytime the radio is in transmit mode. If pulled "low" externally,
it will put the radio into Transmit mode.
It is not recommended that the signal be used to key an external amplifier
directly for a couple of reasons I won't go into detail on here.
However, you CAN use that signal to drive a small 12 volt relay (Omron, Radio
Shack, etc.) between pin 3 ("Send") and pin 7 (13.5 volts. Make sure the relay
used requires no more than 20 ma of current to drive. Be sure to also properly
install a "snubbing" diode, such as a 1N4007, across the relay coil to prevent
inductive kickback from the relay coil back into the IC-910H logic circuits.
The relay's contacts can then drive your Mirage amp's relay line to ground.
For years I have used multiple amplifier keying interfaces such as this with
all of my Icom radios used in contesting.
Ron
WW8RR
-----Original Message-----
From: vhfcontesting-bounces@contesting.com
[mailto:vhfcontesting-bounces@contesting.com] On Behalf Of Jon Casamajor
Sent: Monday, June 15, 2009 4:31 PM
To: vhfcontesting@contesting.com
Subject: [VHFcontesting] IC-910H and Mirage Amp keying
Had a great time this past weekend in the June contest! I put a new Mirage
brick on for a little more 2m power. I about went nuts listening to the relay
chatter so I want to hard key it but I'm not sure which pins to solder up a
cable to. The pin out for the accessory 8 pin show pin 2 as GRND and pin 3 as
SEND. Do I go from 3 to the center pin and 2 to the shield of the RCA? The
IC-910 manual says zip about keying an external amp and the Mirage amp only
says you need to pull the RELAY line low. (GRND)
I bought the B 2518 G Mirage amp from AES btw. The first two were DOA so I
called Mirage who sent me a new one, 2nd day air and a return label to send the
second one back directly to Mirage. If you ever need a contact at MFJ who
cares and will take care of you, ask for Bob Ellis who is the service lead. He
has helped me out twice recently. He has been there forever.
Thanks in advance for any help with the keying.
Regards,
Jon-K6EL
k6el@comcast.net
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