[ICOM] IC-756Pro Linear amp SEND relay kaput

[Kenneth D. Grimm, K4XL]

Adam Farson wrote:

><snip>
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>Required reading when connecting an Icom transceiver to an amplifier whose
>keying V/I rating exceeds 16V/0.5A;
>
>http://www.qsl.net/icom/auxrelay.html
>
><snip>
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>Cheers for now, 73,
>Adam VA7OJ/AB4OJ
>
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>  
>
I couldn't agree more!  Rather than spending "real" money for an IC-756ProII relay to an Alpha 78 relay interface, click on the link at the bottom of the above linked page labeled "Here."  This simple little circuit works like a treat.  I've built several of them for myself and friends using "ugly bug", vero board and printed circuit techniques.  How can you go wrong with one transistor, one resistor and one diode?  

All of my amps, commercial and homebrew, use positive voltage keying on the relays, so I used the diagram at the bottom of the page.  (Why would anyone use negative voltage keying?)

Shopping at All Electronics you can find a TIP32C for .65, a neat little Hammond plastic box for $1.20, 1K resistor .50 (you get 9 spares at this price),  1N4002 $1.00 (11 extras), a 10' cable with RCA plugs on each end for $1.00.  So, not counting the bit of pc board, vero board or whatever you decide to mount this on, the total cost would be $4.35.  If you have any kind of junk box at all, the cost might be much lower!  This is not rocket science.  Anyone can build this gadget.  :-) 

All of the parts are available from other sources, I just happened to have the All Electronics catalog here at the computer and checked on their prices.

-- 

Ken K4XL
k4xl at arrl.net

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