Making an adapter

This question is aimed at Alan but anyone else with knowledge please feel free to help.

I have just realised (partially because I was trying to remember the MicroAvionics headset jack from memory rather than seeing one) that I have a problem with the mic side of an adapter I am trying to make to connect a MicroAvionics headset to a Kenwood 2 pin radio. The Kenwood has speaker on the 2.5mm socket and I have no issue with making the speaker part from a 2.5mm pin to a 3.5mm socket.

The radios 3.5mm mic socket supplies the pin tip with 5v with ring for mic and sleeve for ground. I need to make a 3.5mm pin to connect to a 2.5mm socket. I thought the MA headset jack used a mono 2.5 mm pin but it is stereo. I was planning to leave the 5v supply (that the Kenwood is trying to push through the tip) disconnected as it is not wanted in the headset and had thought that I needed to connect the ring to the 2.5mm mono jack tip and the ground to the 2.5mm mono sleeve. Now I see there is a ring there on the MA headset (the 2.5mm is stereo not mono) so I presume this is for the earcup PTT. Would connecting the mic tip and ring together work meaning that the only PTT available is on the radio itself? Is there a way of wiring this so the headset PTT can still function?

Hi Fanman,

What model Kenwood have you got. Seems odd that the 3.5mm and 2.5mm jacks are reversed compared to the 'standard'.

I haven't any experience with Kenwood but if I can find the circuit on the net I can confirm how the PTT functions. I think the MA headset just uses the tip and sleeve, I don't think the ring is used. The PTT connects the mic into circuit and the small current flow is sensed to put the radio into transmit.

Wire it as you suggest leaving the +5 disconnected and let me know if it works.

Found this on t'web, can't vouch for its accuracy

Alan, it's actually a Puxing PX777 2m band VHF which is effectively a Chinese copy of the Kenwood sets.

Here is a website showing the radio connections for a headset...

http://www.swharden.com/blog/2009-04-22 ... schematic/

I'm happy with the crossover of the speaker from 2.5mm Kenwood to 3.5mm MA, it's how to swap the mic from the 3.5mm Kenwood to the 2.5 MA that I am unsure of. I know the Kenwoods 3 parts to the 3.5mm pin are tip - 5v supply (to be left disconnected), ring - mic, sleeve - ground. How the mic and ground connect to the tip, ring and sleeve on the 2.5mm MA jack is what I need help with.

Interesting, the web site you gave confirms the connections on the picture I posted.

I know the Kenwoods 3 parts to the 3.5mm pin are tip - 5v supply (to be left disconnected), ring - mic, sleeve - ground. How the mic and ground connect to the tip, ring and sleeve on the 2.5mm MA jack is what I need help with.

The connections on the Puxing are not as you think, the sleeve is the PTT connection (for a separate switch, not one that connects the mic) and the common of both the microphone and the PTT switch go to the sleeve of the 2.5mm jack.

The tip of the 2.5mm socket for the MA headset should be connected to ring of Puxing 3.5mm jack, then sleeve for the MA headset to the sleeve of the Puxing 2.5mm speaker jack.

Now here is the problem, I don't know if the MA headset can be configured with the PTT switch to a separate connection. Has the headset got some DIP switches so that it can be configured to work with different radios? I don't know if the dedicated paramotor headset has this facility as does the model aimed at microlighting.

It sounds like you might need a little interface unit.

Cheers,

Alan

Some very interesting developments on this one! Yes the MA paramotor headset does have 12 dip switches inside one earcup. I'm splitting this project into 2 parts and calling part 1 a complete success...

I had a spare CT44 cable lying around. This is an adapter with a 2 pin MA socket to connect to Yaesu/VS radios with single pin (tip, ring, another ring, sleeve). I cut off the Yaesu end and did some circuit continuity testing with the 3 wires and the shielding that remained. The shielding was wired to the sleeve of both 2.5mm and 3.5mm sockets. One wire went to the 3.5mm tip (MA speaker), while the other 2 went to the 2.5mm tip and ring (MA mic).

So... I hooked up the audio as planned... Puxing 2.5mm tip to MA 3.5mm tip and Puxing 2.5mm sleeve to MA 3.5mm sleeve. Tested at this stage and the audio was coming out of both headset speakers nicely. I then went to connect the mic. I connected the Puxing 3.5mm ring to the MA 2.5mm tip and then misread what you wrote next! I connected the Puxing 3.5mm sleeve to the MA 2.5mm ring. This happened because my wife has hasseling me to clear the dining table for dinner and I rushed! Anyway, when I then tried it it all worked!!!

So what is the current state of play? Well, it works a treat and doesn't require any switching of the dip switches from using Vertex Standard airband radio, PMR radio or Alinco 2m sets. So I declare phase 1 a success.

So why do I need a phase 2? Well at present the only functioning PTT is the one on the side of the radio itself and the sidetone in the headset is not functional (sidetone allows you to hear your transmission to stop you thinking you need to shout!).

Having got the basic architecture in place, is there an enhancement to allow the earcup PTT to function which should bring the sidetone into play? Failing that can a separate PTT be incorporated into the adapter for ease of access, (although I suspect a separate PTT will not enable sidetone)?

These radios cost me £25 each brand new for 5W transmitting power 2m band radios that are at least equal to the Alinco except they have lithium ion batteries with intelligent chargers, are smaller and much lighter. The Chinese companies bought the license to manufacture Kenwood radios under their own names so many of them are quality pieces of kit. The downside has always been that the Kenwood mic/speaker jacks have no commercially available adapter to work with Lynx or MA headsets and experts will tell you it can't be done, however now we know it can!

That's excellent news Fanman.

Firstly do you have instructions on what all the DIP switch settings do?

You struck lucky with the mic connections due to the sleeves of the MA sockets being common, this gives the return connection for the mic.

I connected the Puxing 3.5mm sleeve to the MA 2.5mm ring.

This may be your saviour which is why I ask about the DIP switches. I imagine one of the settings will give the headset PTT on the ring of the MA 2.5mm.

You could continuity test (providing it's low power off a multimeter or similar) to find if there is a setting as I imagine. If this isn't the case then a little circuit with 2 transistors and 4 resistors will make the PTT setup work.

The sidetone will only work from the MA PTT as you say. I have modified two radios so the sidetone function is in the radio but it is a bit technical. They then provide sidetone with a simple passive headset which is great.

Cheers,

Alan

Having woken up at 4am some further testing has taken place!

I have a Jingtong JT208 radio (2.5W transmit power 2m band) that has a single pin (stereo 2.5mm) for headset. A few years ago I found a Maplin connector that allows the MA headset to operate fully giving full use of earcup PTT and therefore its sidetone as well, so we know now it can be done! I used my multimeter like before to identify the wiring in this adapter and found that again it has both MA sleeves connected to the Jingtongs sleeve, the MA 3.5 tip to the Jingtong ring and the MA 2.5 tip to the Jingtong tip.

On the basis of this I disconnected the Puxing 3.5mm sleeve to MA 2.5mm ring and left this open. The effect on operation was zero so obviously not required for basic transmitting and must be part of the earcup PTT circuit (and therefore sidetone).

So then I changed the Puxings 3.5mm mic connection so the Puxing 3.5mm now has its ring to the MA 2.5mm ring and the sleeve to the MA 2.5mm tip. I now have use of the headset PTT and sidetone but the received audio (on another radio) from transmission through the MA mic using the earcup PTT is poor. This may well be because the wiring is just twisted together while I establish the connections! Perhaps it's time to go to solder.

The dip switches in the headset are currently set for -

EQ gain off

Mic gain medium

Mute sensitivity off

Transmit level high

Second radio lead mic output high

PTT type resisitive ground

Mic audio on tip

Mobile phone transmit level high

Mobile phone receive level high

These are the standard settings for the MA headset as it comes from the factory and are the settings for... Some Icom airbands, PMR sets, Alinco 2m radios, Vertex Standard airbands and various other 2m band radios.

I think I know what's happening.

Because of the way the MA mic is wired I think you have a series resistor in line with the mic connection to the Puxing. The PTT is now connected as it should be to the Puxing.

Try this:

Get hold of a 1/2.2/4.7 microfarad minature electrolytic capacitor.

Whilst in transmit measure the voltage between the MA 2.5mm tip and ring and note the polarity.

Connect the capacitor between the tip and ring observing the correct polarity, + to +.

See if the received audio is now as it should be . This is a little bit of guesswork so may not work.

The DIP switch that selects Mic on tip, is the other setting Mic on ring by any chance That may be your answer.

Cheers,

Alan

Hmmnn... soldered it all up and nothing on the mic front! Took it apart and reconnected the previous except this time using terminal block for all connections rather than twisting. Nothing until I swapped the dip switched from mic on tip to mic on ring. Now I have the earcup PTT working perfectly but no sidetone

I can live with having to change the dip switch setting, am pleased to have earcup PTT but I would like to have the side tone.

OK, good so far, try one more thing.

Change the switch that you have labelled 'PTT type resisitive ground'

Just a hunch,

Alan

I did try that but on reflection I think it was before I changed the mic from tip to ring so it warrants another try. Another thing I have realised is that if I can't get the sidetone working in conjunction with the PTT then there is a separate remote switch for selectable sidetone within the MA headset. It would mean it is on all the time (it is used for tandem work normally) but it is an answer.

Phase 2 complete and again total success. 2 adapters made up in full. With mic set to ring rather than tip and PTT type changed from resistive ground to hard ground I have full functionality with perfect transmit and receive quality. I have full use of headset PTT with sidetone coming in when PTT is depressed without having to engage selectable sidetone within the headset. This solution is everything I wanted to achieve and totally the result of Alan's patient assistance. Thankyou very very much.

So £25 radio (license built Kenwood copy) better than Alinco with lithium ion battery and intelligent charger with £7 adapter to suit MicroAvionics headset. Result!

It's good to help fellow PMC members.

We've all got different skills so I like to chip in where I can to improve the paramotoring pleasure.

Where did you get your Jingtong radios for £25?

Cheers,

Alan

I paid £9 for a brand new Jingtong JT208 and £25 for Puxing PX777 but these were in China. They are still pretty cheap when bought through ebay in the UK and shipping is paid.

Hopefully I will be able to repay your efforts if my FB harness tests work out as they should.

Hi,

I have just bought a Microavionics MP001 headset. I have cheap 2M radio that is wired the same as Kenwood radios.

I stupidly thought that the connectors were standard on the radios and headset.

Am I correct in thinking that I need to make an adaptor from the headset to the radio?

If I plug the radio in as it is it goes into constant transmit mode.

If so I can see above that there is talk of having a working solution, could you please post a wiring diagram so that I can make one.

Or supply a link where I can buy one.

Thanks

Barry

I wonder if anybody can help with a little headset problem I have ....

Ive got a airzone microlight headset that I wondered if I could just put the lynx connectors on to make it work with a lynx microlight powered interface.....

I also have a microavionics paramotor headset do you think this might be adapted to work with the lynx interface ?

LOL there was me thinking I was clever working out the correct resistance for a given LED LOL

SW

Barry, is it the Puxing radio you have?

SW

We each have our own skills, where would the PMC be without you Simon?

Cheers,

Alan

I wonder if anybody can help with a little headset problem I have ....

Ive got a airzone microlight headset that I wondered if I could just put the lynx connectors on to make it work with a lynx microlight powered interface.....

I also have a microavionics paramotor headset do you think this might be adapted to work with the lynx interface ?

Have you got any connection details of the Airzone headset.

Speak to Eddie at Microavionics about the paramotor headset, he's very helpful.

Cheers, Alan

SimonW, would you like me to write a short tutorial (in laymans terms) of how headsets work and typical connections?

Alan

Why not. I am sure that many will find it useful over time when projects like this come up.

SW

Barry, is it the Puxing radio you have?

[attachment=0]Puxing adapter.jpg[/attachment]

Cheers,

Alan

Thanks very much,

No it is not the Puxing radio. It is a tyt-800, all the Kenwood accessories work on it.

It looks like the Puxing is the same so I will try the provided diagram and see how I get on.

Thanks again.

Barry

Alan,

Thanks very much for you help, that diagram worked perfectly. (including sidetone)