Antenna function in PS Speaker Mic NMN6243B not working

[Leadenwah]

I bought a Motorola speaker mic NMN-6243B which has the provision of attaching the antenna to the speaker mic itself.

The Received audio is great, the Hi-Lo volume switch works fine, but when I attach the ( Jedi ) radio's antenna to the speaker mic, there's no reception with the known good antenna
.
Is there something I'm overlooking in the programming of the radio or is the NMN6243B more model specific than just Jedi series? I'm using this on a UHF HT1000, but tried in on 2 different MTX series radio with same results.

Of course, I didn't get any paperwork or instructions so I'm again having to rely upon this forum for help. Thanks.

[N4KVE]

Some Jedi's don't have the required relay on the RF board to allow this. I think 2 ch jedis, & MTX 8000's built after 93 don't have this relay but all MTS 2000's have the relay. Check out your radio. Good luck. GARY N4KVE

[Leadenwah]

Thanks a lot, Gary,

That looks like the answer. The HT1000 is a 16 ch. I'll check it out, but I'm sure that you're right. I didn't recall anything in the RSS about the speaker mic antenna routing.

Thanks again,
Geo.

[phrawg]

There will BE nothing in the rss. The switch
is a piece of hardware in the side of the radio. See the small
round spot near the top of the acc conn ? that is the button that
pushes the switch if it exists. best to be sure is to pop open the
radio and see if there is a real switch in there on the ckt board.
even with no switch the plunger will be there just as a hole plug.
Phrawg

[MTS2000des]

There will BE nothing in the rss. The switch
is a piece of hardware in the side of the radio. See the small
round spot near the top of the acc conn ? that is the button that
pushes the switch if it exists. best to be sure is to pop open the
radio and see if there is a real switch in there on the ckt board.
even with no switch the plunger will be there just as a hole plug.
Phrawg

if you don't feel like opening the radio, simply tune the radio to an active freq, and use a small pointed object to depress the plunger on the outside of the radio. If there is an RF switch, you will no doubt hear the white noise go way up (or the signal disappear completely if it's weak). If there is NO change, you have an RF board which doesn't have the switch.

Is your HT1000 a factory 16 channel or a hack? Look at the model number, a true factory 16 channel will read H01KDC9AA3xN (x being whatever rev A-D), a two channel RF switchless radio tag would have a 1 in this position. Then there's always the possibility that someone swapped out RF boards and and put one in that came from a 2 channel radio.

99 percent of the MTX8000/9000's I've owned did NOT have a RF switch in them as they were never designed to be "public safety" radios.

[Leadenwah]

Good suggestions.

I located the small button in the connector, hadn't paid any attention to those and found the HT1000 had one and it contacted a spring loaded button on the board, but it doesn't affect the received audio. That is, pressing the button did not interrupt the received audio.

Neither of the MTX's had even a contact on the board as predicted.

This answers my question. I should have looked into this before and it's unfortunate that I can't put the antenna up on the speaker mic. I do get very good audio, however, so it's not a complete loss.

I've had a number of Jedis of assorted types, but never knew about that little button. There's always something to be learned and I appreciate you fellows helping me out.

Many thanks,
Geo.

[phrawg]

you are quite welcome to the help. that is the whole idea
behind why we are here. Oh and sometimes pressing the button
will NOT make the reciever go deaf.. If you are in a strong
enough signal area you may not see a change at all.
The radio will receive quite well anyway. The best way to test
is to find a signal that you can hear well with the antenna mounted
but if you take it off the sig is barely there or not at all.
Then use that sig to listen for the change, as pressing the switch
pin will efectively "remove the antenna" from the receive signal
path. If the change is almost as apparent as the complete
removal of the antenna then you have a switch installed.
glad we could be of service to you. Phrawg

[MTS2000des]

that's the one thing about hacked 2 channel HT1000's is they still can't be used with PSM's (well the audio part works but no RF is routed to the remote antenna) and it really sucks as you can't use them effectively in a JVA as the antenna on your vehicle will not be connected...kinda defeats the whole purpose doesn't it!

[craig]

This is a long shot, but another thing you can check is that the psm has the little silver pin on it that actuates the rf switch. I once bought a psm off of ebay in which the previous owner removed the pin because he didn't like the rf energy by his head, but still wanted to use the mic. He would just use a rubber cap to cover the antenna connector on the mic and put his antenna back on the radio. Without that pin sticking out of the mic connector, there will be no rf switch either.

[Leadenwah]

Thanks once again, folks.

Most of the traffic is from repeaters in the UHF business band, but I'll try with a handheld on the talkaound which will assure a borderline signal.

I'll also check for that silver pin. Quite a few users make such custom modifications to personalize their radios and may well forget that they've done so.

Sometimes the detective work, greatly aided by knowledgeable and helpful folks on the board, can be as much fun as correcting the problem. I've learned that the Jedi and Spectra lines have many facets and respond to many tricks which never got into the manuals.

All the help is much appreciated.