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Author Topic: Using IC-718 with an External Tx  (Read 1259 times)
AB8IF
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Posts: 22




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« on: January 05, 2014, 05:50:43 PM »

I'd like to operate a homebrew transmitter using an IC-718 as a receiver only. The necessary T/R switch is already in place. I just need to know how to mute the IC-718 during transmit. The instruction manual is not too helpful though I suspect the ACC socket may have the answer.

Thanks, Roger
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K7KBN
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Posts: 2813




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« Reply #1 on: January 05, 2014, 08:46:31 PM »

I don't see anything on the ACC connector that would be helpful.  50+ years ago, receivers were muted by opening the B+ circuit; a set of aux contacts on an old Dow-Key coax switch would handle this switching function, like on my old SX-99 and SX-111.  Depending on how much power your transmitter runs, you might -- that's might  want to try just shorting the RF input to the 718 when you transmit.
« Last Edit: January 05, 2014, 08:48:34 PM by K7KBN » Logged

73
Pat K7KBN
CWO4 USNR Ret.
G4AON
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Posts: 542




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« Reply #2 on: January 06, 2014, 02:21:20 AM »

You could add a diode to the AGC line at the anode end of D1802 (anode to anode) - a 1N4148 will do. If you check the AGC Voltage when you rotate the RF gain control you will see the effect and use a similar Voltage to mute via an external relay contact.

This method of muting is fairly straightforward to experiment with. It's the same method as used with many boat anchor receivers...

73 Dave
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KH2BR
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Posts: 103




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« Reply #3 on: January 19, 2014, 12:12:38 AM »

the 718 is prone to ESD damage. If you go in there use precautions.
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