Transmit from ear-piece

Hi, I know this is a bit cheeky posting this here, but I am at my whits end with a pmr446 problem.
I currently use Cobra pmr446 radios with over-ear speakers for use by student motorcyclists. The ear hangers have 3.5mm jack plugs and have been working well for a few years.
I have decided to buy new radios and these have come with 2.5mm jacks. Fair dinkum, new ear pieces ordered. When plugged in they make the radio turn on to Tx!
Spoke with importer and they sent me their special 2.5mm plug (turned out to be exactly the same as I had been using. They now don’t want to return my emails).
Just bought some Motorola TLKR T6 radios and these are also doing the same…
Am I missing the point? All I am plugging in is a single, mono jack-plug connected to a small over-ear speaker. What have the manufacturers changed?
Your thoughts would be appreciated,

In reply to G1STQ:

Am I missing the point? All I am plugging in is a single, mono jack-plug
connected to a small over-ear speaker. What have the manufacturers changed?

Just a thought … are the sockets perhaps stereo type, with three separate conductors? If you plug a mono jack plug into such a socket, it will short out two of the conductors, with unpredictable results.

Walt (G3NYY)

In reply to G1STQ:

Hi, I know this is a bit cheeky posting this here, but I am at my
whits end with a pmr446 problem.

Any Real Radio Ham would have modified them to work on all bands and all modes, using nothing more than an empty baked bean can, a rusty six inch nail, and a bag of Pork Scratchings :wink:

Club tomorrow nite?

73 Mickey

In reply to 2E0YYY:
With comments like that - more like fight nite tomorrow…

In reply to G3NYY:
The plugs have 2 contacts only Walt…the plot thickens…?

In reply to G1STQ:

The plugs have 2 contacts only Walt…the plot thickens…?

Yes, but do the SOCKETS also have only 2 contacts?

Walt (G3NYY)

In reply to G3NYY:
Don’t want to break the seals on the radio in case they have to go back…

In reply to G1STQ:
Plug in a 2.5 three band plug - unwired.
Transmit Yes Walt’s wrong.
Transmit No Problem solved.


Roger G4OWG

ps Walt is never wrong
pps If he is it’s a brave man who tries to tell him :-o
ppps It might not be that simple as the earpiece may be needed to make the contact :slight_smile:

In reply to G4OWG:
I agree Roger…braver man than me anyway.

I’ll pick a 2.5mm plug up tomorrow/Friday and have a play.
I had not thought of that.
Any idea what bands I’d need to solder to for a mono-speaker

In reply to G1STQ:
2.5mm TRS / jack plug…
“1. Sleeve: usually ground
2. Ring: Right-hand channel for stereo signals, negative polarity for balanced mono signals, power supply for power-requiring mono signal sources
3. Tip: Left-hand channel for stereo signals, positive polarity for balanced mono signals, signal line for unbalanced mono signals
4. Insulating rings”

Would I therefore wire the speaker to the tip (+) and Ring (-) and join the ring to the sleave…or leave separate?

In reply to G1STQ:

Hi John, if all you are trying to do is use the earpiece for listening & the radio only has a single 2.5mm jack socket for a speaker-microphone, I would suggest using the ring & sleeve only, as the tip is more likely to be the mic / ptt line. If this is wrong the simply use the tip & sleeve only. No link between ring & sleeve will be necessary.


Mark G0VOF

In reply to G1STQ:

Ten seconds with Google turns up all sorts of speaker mikes or headsets for use with a T6 all showing the stereo plug on the cable.

Typically these headsets/mikes use an electret element so there is a small voltage available to power the unit. PTT is signaled not by earthing one connection but by the impedance of the mike appearing across the connections. i.e. connect the mike to the input and earth and the rig will PTT. It’s been this way on handies since the mid-80s.

The fact that when you connect a fairly low impedance speaker across the tip and sleeve causes the rig to PTT suggests the tip is the mike input, the ring is the speaker and the sleeve is earth.

It could be the other way around and the mono plug you are inserting is shorting the ring and sleeve. However, the sleeve is the earth so you have a 50% chance of getting it right 1st time whichever of the ring or tip you connect to.

Here’s a hint: one way it will work and the other will cause it to PTT.


In reply to MM0FMF:
I need better eyes and not-so sausage fingers…OMG, 2.5mm plugs are small!

In reply to G1STQ:
OK then.
I seem to be needing help, although it appears a bit stupid of me to ask on here about connecting 2 wires up for a speaker.

PMR446 radios have changed the way they accept over-ear type speakers and I cannot fathom out what the hell they have done. This is afecting my new Motorolla radios and some Cobra ones bought last week.

I have a piccy of the offending little socket…

I have tried a 2 band plug and gone through all connections possible and the same with a single band plug. Am I really that stupid?

In reply to G1STQ:

I’ve needed glasses for reading for 10 years now. Until about 9 months ago I could get by in good light. Now I need glasses for any close in work. They even help when using a computer although I can get away still without them. So I have total sympathy for you.

The secret is to have a small vice that holds the plug and to ensure you have the correct cable size. Preparing the cable first is very important. Trim to length, bare conductor and tin, the solder. You need a decent iron and tip too.

Practicing the preparation on scraps of wire again and again helps. When you are confident, you can do it live on the real wire. Then take it apart and put the cover on that you forgot and solder again. Then start again with a new plug and cable! :slight_smile:


In reply to MM0FMF:
I think it is tip and ring…the problem may well lie with my eyesight.
Not realised how bad it has got lately :frowning: