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Need advice from our audio guru?s

NYTOM

Well Known Member
Installing PM 3000 . Have PTT?s on sticks with single unshielded wire that ground to frame near stick. I?m afraid there going to pick up noise so I thought I?d have them trip sub miniature relays right at the intercom so everything will be shielded. The short lines (4?) from the intercom to the relays will be shielded but will the line that is switched by the relay pick up buzz from the relay coil? The only other thing I can think of is running new two conductor shielded lines to each PTT so I can ground to the audio ground and not the power( frame) ground right at the stick. There?s a real science to keeping your audio clear and pure.
 
Your relays are not needed. Most intercoms use a relay internally for the PTT, so you are just adding unnecessary complexity. Wire it like the installation manual says and you?ll be fine.
 
What Mike said. There's no audio information on the PTT line; it's simple yes/no control. There's a pure current-limited DC voltage on the PTT line from the radio, and when the PTT button takes it to ground, the radio senses that at goes into transmit mode.

Charlie
 
Thanks Mike & Charlie.

That makes sense. I wasn?t aware of the internal relays. ;)
On the intercom schematic it shows both the pilot & co-pilot PTT activating by shorting the PTT with the audio Lo. I figured all that unshielded PTT wire length running along lighting, auto pilot and trim wiring might pick up a lot of noise. Been reading all kinds of articles on the web about eliminating audio noise and it?s got me over concerned. Thanks for slapping some sense into me. Sort of like consulting the internet about a slight pain in your finger and coming away thinking you have a terminal illness. :eek:
 
Sort of like consulting the internet about a slight pain in your finger and coming away thinking you have a terminal illness. :eek:
Or convinced you are dying because you remember being "vaccinated for cooties" while in kindergarten. :D
 
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