aftermarket PTT switch

[Jim Peace]

Just flew a J model that has an older king audio control panel and maybe a sigtronics intercom.  There was no PTT switch on the right side last time I flew it so I asked that my friend install one of those portable ones.

It has a mic jack that plugs into the airplane and another jack that my headset mic plugs into and a switch to velcro to yoke.

When I plug in using this configuration we cannot talk to each other and I cannot transmit out.  Removed the PTT and we can talk to each other.....

Anyone have any idea what the deal is?  Is life really this hard?

The dip switch on my Bose a20's are in mono... but should it really have anything to do with dip switches?

 

 

[tmo]

12 minutes ago, Jim Peace said:

The dip switch on my Bose a20's are in mono... but should it really have anything to do with dip switches?

No, this would only matter if you had audio on just one side.  Mono is basically the lowest common denominator, you're good for troubleshooting.

Can the other pilot hear you over the intercom when you press the secondary PTT and speak?  If yes, then here goes your answer - it's really much more involved to properly wire an intercom / switches than adding one inline.  I pretty much gave up for now and will soldier on with a portable solution till I can do it the right way with a PMA450B.  So yes, I'm afraid audio panel / intercom stuff is really hard.

Edited February 2, 2020 by tmo

[Jim Peace]

45 minutes ago, tmo said:

Can the other pilot hear you over the intercom when you press the secondary PTT and speak?  If yes, then here goes your answer - it's really much more involved to properly wire an intercom / switches than adding one inline.  I pretty much gave up for now and will soldier on with a portable solution till I can do it the right way with a PMA450B.  So yes, I'm afraid audio panel / intercom stuff is really hard.

No they cannot...they meaning the pilot in the left seat and the pax in the back

This is a portable unit....

[tmo]

Then your setup is similar to mine.

In my setup the portable intercom "outputs" are plugged into the LHS airplane jacks, so technically I could press the LHS PTT and let the RHS (or passenger) speak, but that's borderline useless.  I have a RHS PTT, but if we're plugged into the portable intercom, it doesn't work, since the source of the audio (portable intercom) is plugged into the LHS connections.

I really hope you manage to figure something out and I can copy your solution.

Also, doesn't the portable PTT switch need to be hooked up to the portable intercom?  Not sure if it changes anything, not even sure I recall correctly.

[Jim Peace]

Just now, tmo said:

Also, doesn't the portable PTT switch need to be hooked up to the portable intercom?  Not sure if it changes anything, not even sure I recall correctly.

The intercom is a panel mounted sigtronics......just using the external PTT switch on the right side and it does not allow the right seater to hear or transmit or be heard....

[tmo]

In that case the panel mounted intercom most likely has a pair of pins labelled "co-pilot PTT", in addition to the "pilot PTT".  The pilot ones are connected to your yoke-mounted PTT switch, the portable one on the co-pilot yoke is not, hence the audio from the co-pilot jacks isn't routed to the transmitter / radio when the PTT is pressed.

IOW the portable PTT isn't doing anything.

I know it's not the unit you have, but for a high-level overview of the wiring take a look at the second page of the PM 501 data sheet.

[carusoam]

Jim,

See if you can find the manuals for the intercom and audio panel...

Their set-up is complex enough that it can’t be done by one set of ears...

On ancient equipment... the standards were to have options turned off....

And quirky words to describe things were all the rage...

I think ‘side-tone’ describes what to turn on so you can hear people in the cockpit talking....

In my plane... everything is great... until SIC pushes the PTT button to talk to ATC...

They are having a private conversation at that point...

Good luck finding the right set-up...(?)

Best regards,

-a-

[tmo]

14 hours ago, carusoam said:

I think ‘side-tone’ describes what to turn on so you can hear people in the cockpit talking....

In my plane... everything is great... until SIC pushes the PTT button to talk to ATC...

They are having a private conversation at that point...

Sitetone is audible feedback to someone speaking when using a handset or headset as an indication of an active transmission. IOW, it is you hearing yourself talking while transmitting (on purpose, so you don't shout, not voices in head).

I think that when the RHS PTT is pressed the sidetone should go to all headsets (or at least the front ones) but the source should be the RHS mic.  @carusoam - do you perhaps have some kind of [co-]pilot isolation enabled (perhaps inadvertantly)?

[RLCarter]

Check the new PTT switch on a different aircraft, sounds like the headset jacks aren't wired correct. Sidetone is hearing yourself transmit, The PTT is fairly simple it just grounds the wire IIRC... I have an old headset with a PTT button on the earmuff

[N201MKTurbo]

I had the same problem with my old M20F. 

I cut the plugs off the PTT switches and wired one dry contact directly to the PTT terminal on the jack. Everything worked properly and it was much cleaner with no big plugs dangling around.