Fighter Style Comm control on Throttle

[BHunt]

Hey everyone

For some background, I?m a USAF pilot, having flown T-38s and F-16s. In those jets, the comm control is on the throttle controlled by a switch that had a Forward and Aft position that would auto return to center. Each position would key the Mic for each radio. For example, in the T-38 forward would be UHF and aft would be VHF. I am trying to set up my RV-8 in a similar manner. I have an IFD-440 as my Comm1, a Dynon comm radio as my Comm 2 and both go into a Garmin 345 audio panel. I am trying to have one position key the mic for one radio, the other position key the mic for the other, and the center just be intercom.

I found the below throttle which is CLOSE to what I want. Although, talking to Paul the owner, how he has it set up is one position keys the radio, the other keys in intercom and the center is off. He was unsure how to set it up like I am requesting but said if someone could figure it out he?d make it! Has anyone tackled this before or knows how it could be done with the below product or know of another switch that would allow it?

https://www.3dstickandrudder.com/sho...-slider-switch

[rmartingt]

Originally Posted by BHunt

Hey everyone

For some background, I?m a USAF pilot, having flown T-38s and F-16s. In those jets, the comm control is on the throttle controlled by a switch that had a Forward and Aft position that would auto return to center. Each position would key the Mic for each radio. For example, in the T-38 forward would be UHF and aft would be VHF. I am trying to set up my RV-8 in a similar manner. I have an IFD-440 as my Comm1, a Dynon comm radio as my Comm 2 and both go into a Garmin 345 audio panel. I am trying to have one position key the mic for one radio, the other position key the mic for the other, and the center just be intercom.

I found the below throttle which is CLOSE to what I want. Although, talking to Paul the owner, how he has it set up is one position keys the radio, the other keys in intercom and the center is off. He was unsure how to set it up like I am requesting but said if someone could figure it out he?d make it! Has anyone tackled this before or knows how it could be done with the below product or know of another switch that would allow it?

https://www.3dstickandrudder.com/sho...-slider-switch

I've been looking into something similar, though my plan was to run Com 1 off the stick and Com 2 off the throttle.

The trick isn't the switch--any (on)-off-(on) switch can do the job--but rather that you need a relay to switch the mic input and drive the PTT input on the radio.

It came up a few years ago and I found it when I was doing my research:
http://www.vansairforce.com/communit...ad.php?t=60249

[Terry Lutz]

I am of the same way of thinking. On my RV-8, I have a standard throttle on the left side. The handle is basically a tube, so I installed a miniature coolie hat switch in the end of the tube. Pushed forward, it keys the mic, and it is spring loaded to center. Then I got to thinking, why not put the flaps on the up and down functions of the switch. So for flap operation, I don't have to take my hand off the throttle. Still nothing in the aft position, but I guess I could make it key my #2 radio.

For wiring, I made a slightly thicker throttle arm, then cut a slot in the back side to allow a ribbon of wire to nest down the back side. Works fine, and hopefully will last a long time.

[rapid_ascent]

I would think that a DPDT switch could work. One side for switching the mic input and one side for the PTT. I'm not sure why you would need to use a relay.

[N941WR]

That quadrant is made by Dayton Murdock (DJM, Mfg) and the grip is an overlay that goes on tope of it.

Why don't you try to contact Dayton and see if he can't turn out what you are looking for?

[Agent86]

Hi all, Long time lurker here.
Have a look at this schematic. It uses one DPDT relay to switch the output from the comm panel (with COM 1 selected as Tx). The Throttle Switch need to be a DPDT (or you could use two DPST Mom switches on a Mil style Stick grip...just don't push them both at once as Com2 takes priority!)

You select Com 1 as tx and receive on both Com 1 and Com2
You won't get the indication on the GMA that you are Tx on Com 2.

[Agent86]

I just had another thought. The GMA 3xx and 2xx support Split-Com mode. This is where the Pilot and Copilot can each transmit on their respective radios.

If you wire the Pilot and Copilot "Forward/Com 1" switch together and connect to Pilot Mic Key in and the "Aft/Com 2"switch together and connect to Copilot Mic Key in, then either pilot can TX on Com 1 by pressing the fwd switch and Com 2 using the aft switch ...when Split-Com is selected.

When Split-Com is NOT selected, then pressing fwd OR Aft by either pilot will transmit on the Com selected for TX on the GMA.

If you don't want the dual com in the "other" seat, then that seat will only have one switch connected to Copilot Mic Key in. The down side of that is they would only be able to Tx on Com 2 in the Split-Com mode.

Would this work?

..Edit. This won't work as each mic is switched by the GMA ie Pilot Mic to Com1 and Copilot mic to Com2 ... so back to needing a relay as my post above.

[FinnFlyer]

Originally Posted by BHunt

Hey everyone

...I am trying to have one position key the mic for one radio, the other position key the mic for the other, and the center just be intercom. ...

PTT inputs are just "ground to talk". So a simple (on)-off-(on) switch should do: the center connector to ground, the outer connectors to the respective radios.

No sure why you'd have to switch mic between inputs, unless the radios loads the mic too much when both radio inputs are attached to a mic.

Finn

[fl-mike]

I used this, glued into a sleeve that slides into the standard DJM handle and is retained with a small screw.. Drilled a small exit hole for the wires and secured to the lever.
https://www.otto-controls.com/t1-2-way-mini-trim

[BobTurner]

Originally Posted by FinnFlyer

No sure why you'd have to switch mic between inputs, unless the radios loads the mic too much when both radio inputs are attached to a mic.

Finn

That?s the answer. Aircraft mikes are relatively low input impedance devices, and when you plug into two radios that input impedance is effectively cut in half. It will work, but the output will be reduced.