Ebaybanned headset, ptt

[Gasmlt]

Hello all,

 

I have just received my Cav. replica headset and it's for a Kenwood, I would like to convert it for my Midland G7 ! Any one have a circuit diagram of this head set or the pin layouts of the Midland G7. aNY Idea for a PTT works electrically ?

 

Come guys this has been done before!

 

Thanks

 

Pierre

[Spam]

Right, I'm not sure if the G7 is the same, but i have converted several of the Cavalvy headsets to work with the Midland GTX700-900 range.

 

The guys at Midland are actually very helpful and if you e-mail them, they'll gladly send you a circuit diagram showing how the headsets are wired.

 

As to how to redo the Cavalvy headsets, I've actually been meaning to do a how-to guide for a while, so I'll get one knocked up just now.

[Gasmlt]

Right, I'm not sure if the G7 is the same, but i have converted several of the Cavalvy headsets to work with the Midland GTX700-900 range.

 

The guys at Midland are actually very helpful and if you e-mail them, they'll gladly send you a circuit diagram showing how the headsets are wired.

 

As to how to redo the Cavalvy headsets, I've actually been meaning to do a how-to guide for a while, so I'll get one knocked up just now.

 

The headset I have is wired this way:

 

 

Now what I need to know about the midland !

 

Let me know when you write up something ! Also onmidland, pins are swapped but not sure of all pins, close but need help! If you can send me only the pin layout, will be great on my email gasmlt@onvol.net or even here !

 

Pierre

[Spam]

Right, first things first - the Headset Jacks for the Midlands are a 3.5mm Mono Jack and 2.5mm Stereo Jack with 10mm between the Pins. Motorola 2 pins are slightly closer together (8mm I think) and Kenwoods slightly further apart (12mm). Icom connectors are 10mm as well and fit perfectly.

 

It doesn't actually matter at all if the jack connectors are Mono or Stereo, and its usually the 3.5mm jack for the earpiece speaker and the 2.5mm jack for the microphone, so you only need to change the connector end if its a Kenwood or Motorola style 2-pin connector.

There's several ways you can adapt it to fit your radio - Either:

a. Buy an adaptor

b. Chop the connector off and wire on new jack plugs

c. My preffered method : connector surgery

 

What I do is take a sharp knife and slice off the hard plastic shell surrounding the 2 pin connector. Be careful when doing this to not cut too deep and catch some of the wires within, Usually the shell will come off fairly easily and inside the connector will be all the wiring coated in hot glue or soft plastic (see first pic attached) which you can either heat up with a lighter and stretch/squeeze the connectors together, or cut off with a sharp knife to leave the 2 jack plugs hanging loose.

 

Either way, you want to then test fit the jacks in your radio, then fix them in place - a coupla dabs of hot glue does the trick, then I like to seal the connector back up with epoxy (Games Workshop Green Stuff / Kneadatite does the trick perfectly - second pic attached) so the wiring doesn't get damaged.

[Spam]

Is that circuit diagram for the Cavalvy Headset? because it looks nothing like the actual wiring inside one..

 

 

Wiring for a midland is attached:

[Spam]

Basically, every cavalvy headset I've done, once I've made sure the 2-pin connector fits the radio, I've done all the re-wiring inside the PTT box itself.

 

All thats really required is to add a 2.2KOhm resistor to the PTT switch, then change the mic wiring so that the switch and resistor is in parallel as opposed to in series.

 

On the 5-pin connector the headsets use, pins 1+2 are the headset, 3 is ground (not connected usually) and 4+5 are the Mic +/-

 

Pin outs on the 5-pin connector go clockwise from the nub on the PTT male connector (they should be numbered on the actual headset connector as well).

 

1. 3.5mm Jack Tip: Ear Piece +

2. 3.5mm Jack Outer: Ear Piece -

3. Not Connected

4. 2.5mm Jack Outer: Mic -

5. 2.5mm Jack Tip: Mic +

[Spam]

Righto, techy stuff you can ignore if you want:

 

Midland Headsets have the PTT switch wired in parallel to allow for VOX functionality and for the PTT button on the radio itself to still function.

 

Standard Push to Talk headsets have a basic momentary switch in series with the microphone in the circuit, thus when the button is pressed, the circuit is complete and the microphone goes on, and when the button is released, the circuit is broken and the microphone doesn’t work.

 

If the circuit is broken in the PTT, neither VOX or the radio PTT would work.

 

The midlands get round this by having the Switch (and a resistor) in parallel with the microphone. This means that the microphone in the headset is constantly connected, however the radio itself will only transmit if either:

 

a. The PTT button on the radio is pressed.

b. Vox functionality is enabled and the mic picks up sound.

c. The resistance in the microphone circuit is below 1KOhm

 

The microphone has its own internal resistance (on the cavalvy ones, its usually between 1.2 and 2 KOhms, which is fine for the circuit diagram above), and how you wire the mic is dependant on what the resistance of the mic is.

How the PTT in parallel works is that when the switch is triggered, it drops the overall resistance of the circuit below 1KOhm. The 2.2KOhm resistor is required, as without it when the switch is triggered the circuit would short and bypass the microphone altogether.

 

You can actually use a headset where the PTT wiring is in series with the midlands, however the resistance of the mic circuit must be below 1KOhm, and you won't be able to use VOX or the radio PTT button.

 

Likewise if you have a headset where the mic resistance is below 1KOhm and you want it wired in parallel so that Vox/radio PTT still works, you would need to add in an extra resistor to take the overall mic resistance above 1KOhm, otherwise the headset would just constantly transmit regardless of whether any buttons were pressed.

[Gasmlt]

Righto, techy stuff you can ignore if you want:

 

Midland Headsets have the PTT switch wired in parallel to allow for VOX functionality and for the PTT button on the radio itself to still function.

 

Standard Push to Talk headsets have a basic momentary switch in series with the microphone in the circuit, thus when the button is pressed, the circuit is complete and the microphone goes on, and when the button is released, the circuit is broken and the microphone doesn't work.

 

If the circuit is broken in the PTT, neither VOX or the radio PTT would work.

 

The midlands get round this by having the Switch (and a resistor) in parallel with the microphone. This means that the microphone in the headset is constantly connected, however the radio itself will only transmit if either:

 

a. The PTT button on the radio is pressed.

b. Vox functionality is enabled and the mic picks up sound.

c. The resistance in the microphone circuit is below 1KOhm

 

The microphone has its own internal resistance (on the cavalvy ones, its usually between 1.2 and 2 KOhms, which is fine for the circuit diagram above), and how you wire the mic is dependant on what the resistance of the mic is.

How the PTT in parallel works is that when the switch is triggered, it drops the overall resistance of the circuit below 1KOhm. The 220 Ohm resistor is required, as without it when the switch is triggered the circuit would short and bypass the microphone altogether.

 

You can actually use a headset where the PTT wiring is in series with the midlands, however the resistance of the mic circuit must be below 1KOhm, and you won't be able to use VOX or the radio PTT button.

 

Likewise if you have a headset where the mic resistance is below 1KOhm and you want it wired in parallel so that Vox/radio PTT still works, you would need to add in an extra resistor to take the overall mic resistance above 1KOhm, otherwise the headset would just constantly transmit regardless of whether any buttons were pressed.

 

Thanks very much about your info, will let you know ! The headset in question is an Ebaybanned clone of the Cavalary headset,made for Kenwood, infact diagram is from a Kenwood manual and when I checked mine is same!

 

Thanks

 

Pierre

[Gasmlt]

Is that circuit diagram for the Cavalvy Headset? because it looks nothing like the actual wiring inside one..

 

 

Wiring for a midland is attached:

 

Seeing the midland wiring diagram you posted, I will have to check as on mine, as on my G7, where I have the holes for the plugs,one is mic and other speaker,and noton same hole, is yours same ?

 

Pierre

[Spam]

Seeing the midland wiring diagram you posted, I will have to check as on mine, as on my G7, where I have the holes for the plugs,one is mic and other speaker,and noton same hole, is yours same ?

 

Pierre

 

I have done one of the Kenwood headsets, and I don't remember it being as complicated as that circuit diagram, but I think it might be right enough that the speaker and mic jacks are switched.

 

The larger 3.5mm jack plug should be the speaker, and the smaller 2.5mm one the mic.

 

You can check the jack plugs are wired right by hooking the probes of a multimeter to the bottom and tip of the jack connector and checking the resistance (continuity works as well), the value should be nearly 0 for the speaker, and somewhere between 700-1800 (depending on polarity) for the microphone when the PTT button is pressed.

[Weirdguy]

I just finished converting my ebaybanned TASC kenwood headset to midland. It was pretty easy, all I had to do was switch around some wires, add a resistor, and fix the connector.

 

This is how the wiring looks stock, nothing like that schematic above

[Gasmlt]

I just finished converting my ebaybanned TASC kenwood headset to midland. It was pretty easy, all I had to do was switch around some wires, add a resistor, and fix the connector.

 

This is how the wiring looks stock, nothing like that schematic above

 

True,

 

If you remove resistors, the schematics will be good!

 

This is how mine was done

 

 

 

 

I also glued a small 2mm disk to the switch tip, as a spacer, to take all the slack and work wonders! REs added is 2.2K

 

Regards

 

Pierre

[Spam]

Woops, just noticed that I typed the wrong resistor value in all them posts I made - It is 2.2KOhm you're supposed to use (and what I used in mine).

 

**Edit**, sorted now

 

Glad you got it working ok

 

 

[baelinn]

can some give me a detailed picture of the needed wiring in de PTT for the midland G7 ?

[Spam]

can some give me a detailed picture of the needed wiring in de PTT for the midland G7 ?

 

 

I would suggest reading the entire thread over again and look at the circuit diagram I posted (the last one Gasmlt posted works too, but not when the button on the radio itself is pressed).

[baelinn]

 

I would suggest reading the entire thread over again and look at the circuit diagram I posted (the last one Gasmlt posted works too, but not when the button on the radio itself is pressed).

 

i dont understand the diagram

[Samm]

i dont understand the diagram

I would suggest you do some reading on electronics then

[Spam]

In that case, I would suggest you get someone else to do the re-wiring for you then - it's a fairly straightforward mod, but still requires a reasonable amount of circuit wiring skills.

 

Ask around your friends/family to see if any of them are good at stuff like this and willing to do it for you?

[baelinn]

In that case, I would suggest you get someone else to do the re-wiring for you then - it's a fairly straightforward mod, but still requires a reasonable amount of circuit wiring skills.

 

Ask around your friends/family to see if any of them are good at stuff like this and willing to do it for you?

yeah maybe thats a better idea i'm a welder but dont understand electronic wiring

[DecReg_Jupiter]

I have a question about this as well. except that i have an icom PTT and connector. I saw that the mono vs stereo means nothing earlier in the thread (?). with it plugged into my midland VHF radio I can receive clearly, and when i depress the PTT nothing happens. Will i need to get a new mic pin? Or is it about being serial vs parallel? I will admit that i am not good at electronics but a team mate of mine is and i would just like to know what to tell him needs to happen when i hand over my headset for work.

[Spam]

I saw that the mono vs stereo means nothing earlier in the thread (?).

 

Yep thats right.

 

with it plugged into my midland VHF radio I can receive clearly, and when i depress the PTT nothing happens. Will i need to get a new mic pin? Or is it about being serial vs parallel?

 

Did it work before and its stopped working now? If it worked previously it could be a dodgy mic pin, but I highly doubt it - the connectors themselves won't break in a hurry. Most likely it is either:

 

a: Microphone unit itself is gubbed

b: Wiring needs looked at in PTT

 

First port of call is to borrow a multimeter and check the resistance/continuity over the mic pin.

Hold one of the probes to the tip of the 2.5mm mic jack connector, and the other to the base of the same connector (meter leads with crocodile clips are best for this). You should get a high value if your multimeter is set to resistance (about 1400 Ohms, or off the scale depending on it is wired), or low if set to continuity (not sure of values, but probably something around about 0.0 - 0.1).

Then press the PTT button with the probes still in place, the resistance value should drop to about 700-900 ohms, or continuity will go up (to about 0.5 I think?). If your meter is in continuity mode, it might beep as well when the PTT button is pressed - that's a good sign

 

Check the above and we might be able to help you more.

[Spam]

Bear in mind, that the readings you get will be slightly different depending on whether you have the red or black probe connected to the tip due to the polarity of the mic - that doesn't matter as long as the resistance value goes down/continuity value goes up when the PTT button is pressed - just testing to see if you have a complete circuit.

 

If the resistance value is off the scale/doesn't show when the PTT button is pressed, you have a break in the circuit somewhere.

If it doesn't change the PTT is wired wrong.

If the resistance is near 0.0 you have a short circuit (bare wires touching somewhere).

 

Oh, and the resistance of the larger (earphone speaker) connector should be about 0.0 - make sure you test the right connector .

[halcon_del_sur]

I'm getting the same problem as well:

 

ComTac II with Icom 2 pin on my Midland LXT328.

 

I tested the boom-mics, they work just fine.

 

I'm able to receive radio transmissions but when pressing the PTT nothing happens, can't transmit at all.

 

I'll try these directions and see what happens!

 

Regards.

[halcon_del_sur]

Any help on this will be really, really, extremely appreciated!

 

Cheers.

[xav.100]

UP.

 

i have the same problem, do i need to bridge with a 2.2oHm the mic + & - wires ?