Rallye MS880B

[RotaryWingB2]

Hi,

I'm after some wiring diagrams for the above Aircraft, specifically the PTT switch in the control stick, and associated connections.

Can anyone point me in the right direction?

Thanks.

[happybiker]

Hi Geordie. You probably wont be able to get hold of generic wiring diagrams for the PTT and the interface to the intercomm and radios as these will have installed after the aircraft was delivered. The PTT switch will normally operate a relay to switch the microphone input from the intercom amplifier (if you have intercom installed) to the selected VHF transceiver. It will also provide a ground (earth) to the VHF transceiver to switch it to transmit mode. This can be via a bespoke relay switching unit or a propriety off the shelf unit. Your friendly neighbourhood avionics guy may be able to provide you with further information. You could also check back through your log books to see who installed the radio in you aircraft and ask them to provide the wiring diagrams from the modification.

[englishal]

We had some problems with our Sigtronics SPA-400 intercom. I googled it and found the wiring diagrams on Harry Mendelson's website.

[happybiker]

Try this link for the SPA 400 connection

http://www.sigtronics.com/pdf/air_pdf/spa-400.pdf

[RotaryWingB2]

Thanks guys, it doesn't have SPA400, it's fitted with a Narco CP136 and a MX170C, both of which I have the wiring/installation diagrams for.

A schematic of the relay/PTT set up would help though, the old relays fitted are thoroughly shot, so many broken connections it's impossible to tell what line went where!

[IO540]

I have a TB20 and loads of manuals; they won't be that different, so email on its way to you GS.

[RotaryWingB2]

Thanks very much IO540, much appreciated.