NAV Source Select
 

I'm just planning the wiring behind my panel and would like to be able to select the source (ie GNS430 or SL30) that drives the MD200-306 CDI.

Can I do this? If so I'd really appreciate some guidance :confused:

It can be done. There might be other ways, but I'm guessing you need one of these: http://www.periheliondesign.com/18polerelays.htm

Guy

CDI relay
 

Yes, you can wire two seperate sources (GNS430 & SL-30) into a single CDI. You should use the MD-200-306 indicator from Mid Continent if you wish to have the Back Course annunciator from the SL-30 displayed on the CDI. You would wire all the Main output analog lines from the 4001 plug on the 430 to the Normally Closed contacts of the relay. Wire all of the Nav analog outputs from the SL-30 to the Normally open contacts of the relay. Then the common poles of the relay to the CDI. Here is a list of the individual lines you need to keep in mind, as each one will use one pole of the relay.
Left, Right, Up, Down, Nav Flag +, Nav Flag -, G/S Flag +, GS Flag -, To, From, OBS H, OBS C, OBS D, OBS E, OBS F, OBS G.
In addition to these you should run the Back Course annunciator out of the SL-30 to a pole on the relay the to the CDI (Note there is no BC from the 430 so the NC contact on that pole will be unused. Also you need to run the 430's GPS and VLOC annunciation through the relay and to the CDI.
By my count it would take 19 poles if you include the BC, GPS annunciation, and VLOC annunciation.
You would then have to install a switch in the panel for "Source Select" GNS 430 or SL-30. You should ground switch the relay to energize it for the SL-30 select.
After the wiring is complete you will need to calibrate the CDI to both the 430 and the SL-30's OBS resolvers seperatly.
I have completed this very connection dozens of times in various panels I have built. If you have any question feel free to give me a call and I can explain in further detail. You can reach me 8-5 Monday-Friday at work at Aerotronics. 406-259-5006. Hope this helps.
Jason Smith

Thanks guys. Jason, what relay do you recommend/use?

Relay
 

Steve,
You can use a good quality relay intended for this purpose like the one here:
http://www.aircraftspruce.com/catalo...eri_remote.php
or you can use a combination of small relays, say five four-pole relays.You can find these at any electronics store. You just wire the coils of each one to activate at the same time.

Jason Smith
Avionics Tech