Comm wiring diagram help needed.

Hi all can anyone help me with reading this wiring diagram. Coming off pin #2, the microphone ground, is a circle with a line on top and bottom. What does this symbol mean? Need to know what to do with this wire. Also have a question on how to terminate the shield for the headphones and mics. I understand I should terminate it just at the radio but where? Do I terminate it to the db15 housing itself, to one of the 2 through bolts?

Thanks
Bill

The circle represents the shielding of the wires that needs to be grounded.

As noted, tbe circle represents the cable shield.
I do not know where this came from but I can tell you that it's a piece of junk.
The shield should be used to shield, not to carry the return current.
The mikes are connected in parallel. This may or may not work okay. Do you want ATC to hear both pilots at the same time? If this is an intercom do you want twice the background noise?

It's a Dittel FSG-70 radio with intercom. Here's a full schematic. Also where do I run the wire coming off the microphone jack tab 3/barrel?

William said:

It's a Dittel FSG-70 radio with intercom. Here's a full schematic. Also where do I run the wire coming off the microphone jack tab 3/barrel?

Click to expand...

They show you using the shield to run from tab 3 back to the intercom ground. No modern avionics recommend this. Instead use a multi-conductor shielded cable. Use one of the wires to run from tab 3 back to the mic ground. Ground the shield only at the radio end.

This is a 'hot mikes' (no squelch) intercom. In an RV I can guarantee you will not be happy. Spend a few hundred dollars and get a PS intercom.

Thanks Bob! This radio is going in a kit fox I own. I'm sure it's not a optimized
Setup but the radio will rarely be used in my kitfox and I'm hoping the hot mic will be fine on the rare occasion I have a passenger? Also where do I ground the shield at the radio end?

Thanks
Bill



QUOTE=BobTurner;991204]They show you using the shield to run from tab 3 back to the intercom ground. No modern avionics recommend this. Instead use a multi-conductor shielded cable. Use one of the wires to run from tab 3 back to the mic ground. Ground the shield only at the radio end.

This is a 'hot mikes' (no squelch) intercom. In an RV I can guarantee you will not be happy. Spend a few hundred dollars and get a PS intercom.[/QUOTE]

Ground all the shields at the pin 11 or 12. the headset ground wire there too. The mike ground wire at pin 2.
Even if you use no speaker be sure to wire the intercom off/on switch so you can turn it off when solo.

BobTurner said:

Ground all the shields at the pin 11 or 12. the headset ground wire there too. The mike ground wire at pin 2.
Even if you use no speaker be sure to wire the intercom off/on switch so you can turn it off when solo.

Click to expand...

Will do Bob, thanks for your help! I was a bit confused on grounding the shields because I read a post somewhere that had the shields being grounded to the casing of the db15 connector.

Thanks
Bill

Looks like a 20 year old radio from a glider-----Cumulus Soaring.com????

Agree with Bob, there are better setups out there these days.

Note the listing for "Carbon Standard Microphone"

Mike S said:

Looks like a 20 year old radio from a glider-----Cumulus Soaring.com????

Agree with Bob, there are better setups out there these days.

Note the listing for "Carbon Standard Microphone"

Click to expand...

Yes, I looked up the manual. Use 'carbon standard mike' for any standard aircraft mike. The Dynamic mike input is for a Radio Shack equivalent that puts out much lower voltages than standard aircraft mikes.

The hot mikes intercom is probably okay in a glider, but likely very uncomfortable noise-wise in a powered airplane.

Mike S said:

Looks like a 20 year old radio from a glider-----Cumulus Soaring.com????

Agree with Bob, there are better setups out there these days.

Note the listing for "Carbon Standard Microphone"

Click to expand...

Picked it up for next to nothing and really only need it as a emergency. Will be used in my kitfox not my rv6a.

BR
Bill

BobTurner said:

Yes, I looked up the manual. Use 'carbon standard mike' for any standard aircraft mike. The Dynamic mike input is for a Radio Shack equivalent that puts out much lower voltages than standard aircraft mikes.

The hot mikes intercom is probably okay in a glider, but likely very uncomfortable noise-wise in a powered airplane.

Click to expand...

Thanks Bob for all you help. I'll upgrade it eventually but hopefully it doesn't end up being a paper weight.

BR
Bill