Tone Remote to PM1500 TIB

[kEph13]

Hey Everyone,
My agency got a new PM1500 to use as a base radio, and the company that won the contract wired most of it up but seemed stymied by the tone remote box from dispatch (Motorola L3276). Our dispatch center has one transmitter and 3 receivers, so when they want to simulcast they use our radio to transmit.

One major question is, does anyone have a pinout of the L3276 DB25 connector? I've been singularly unable to find it - it's currently hooked up to the old radio, so if I really need to I can try to trace backwards, but the current wiring is really ugly.

Otherwise, my thought is to connect from the L3276 to the PM1500 DB25 like so:

(L3276 -> PM1500)
PTT(?) -> Pin 1, AUX_PTT
Audio -> Pin 7, AUX_RX and Pin 8, AUX_TX (this is so that it transmits the simulcast and we hear it in the base - will this work at all?)
GND -> Pin 10, GND (Do I need a ground? More than one?)

Is there anything I need to know regarding these connections? Does this look like it'll work? I know I need to play with CPS settings, I'm more comfortable with that then the wiring side of things.
Additionally, pins 24 and 25 on the PM1500 are speaker + and -, can I use these to connect to the standard remote speakers that the control heads hook up to?

Thanks!

[Jim202]

Hey Everyone,
My agency got a new PM1500 to use as a base radio, and the company that won the contract wired most of it up but seemed stymied by the tone remote box from dispatch (Motorola L3276). Our dispatch center has one transmitter and 3 receivers, so when they want to simulcast they use our radio to transmit.

One major question is, does anyone have a pinout of the L3276 DB25 connector? I've been singularly unable to find it - it's currently hooked up to the old radio, so if I really need to I can try to trace backwards, but the current wiring is really ugly.

Otherwise, my thought is to connect from the L3276 to the PM1500 DB25 like so:

(L3276 -> PM1500)
PTT(?) -> Pin 1, AUX_PTT
Audio -> Pin 7, AUX_RX and Pin 8, AUX_TX (this is so that it transmits the simulcast and we hear it in the base - will this work at all?)
GND -> Pin 10, GND (Do I need a ground? More than one?)

Is there anything I need to know regarding these connections? Does this look like it'll work? I know I need to play with CPS settings, I'm more comfortable with that then the wiring side of things.
Additionally, pins 24 and 25 on the PM1500 are speaker + and -, can I use these to connect to the standard remote speakers that the control heads hook up to?

Thanks!

If you send me a PM or email, I may be able to help you a little. Include a valid email in your message.

Jim

[Dorf411]

Manual:

https://www.google.com/url?q=http://rep ... HWVd02Ozhg

We find the L3276 to be a bit of a PITA but not really that bad, is this dealer a M dealer?

[d119]

I'd sure like to know how the PM1500 is interfaced to a TRA. I'm an experienced technician, and I ended up with two dead TIB's over this exact project.

I was using TNA200's to do the interface. I never could get the damn thing to work right, and for some reason two TIB's failed in the process.

According to Motorola, interfacing a TRA to a PM/XTL series radio is "Not a supported configuration". Go figure. Wonder why.

So they can sell you a consolette, of course.... Except you can't get them in 110W.

And yes, you can attach an external speaker to pins 24 & 25 without issue. Beyond 1 speaker, I'd think you'd need to make sure the impedance is properly matched to avoid audio PA issues.

[kEph13]

Thanks! And no, not to my knowledge.
Since you've worked with these before, am I correct that RADIO_RX+ on the L3276 side should go to AUX_RX or AUX_TX on the PM1500? Do you know if I can bridge the pins so it goes to both? Or would that drop the amperage too low?

[kEph13]

Whoops, just saw the other response. That makes me a little nervous...
I don't need anything fancy, I'm not trying to hook up channel selecting or anything. This radio is always on the same frequency. So I'm assuming just connecting audio isn't going to break anything? I hope? I guess this also explains why a ready-made cable doesn't exist.

[kEph13]

One more update - it *seems* to be working. I have the PTTs connected, GND to GND, and RADIO_TX on the TRA connected to AUX_TX on the PM1500. I'm going to play with the pot on the back tomorrow to match up volumes, but when the dip switch was in test mode, it was putting out almost 300mV, which is what the PM1500 claims to want. Strangely, it was still on the factory setting, which claims to output 80-140mV. So I'm not sure how that happened. I'll post any more issues I run across.

[Jim202]

One of the issues with trying to interface to most Motorola radios with any tone remote adapter is that most people forget that there is a DC bias on both the TX audio input lines and the RX audio output from the radio. You may need to add about a 1.0 uf cap in series with the hot connection to prevent shorting out this bias. It will depend on how the remote adapter was constructed.

PTT is on pin 1 of the DB25.

TX audio input on the DB25 is on pin 8.

RX fixed audio output filtered is on pin 9 of the DB25.

Ground is on pin 10 of the DB25.

TX audio low is on pin 11 of the DB25.

Now using the TX aux input may require you to go into the software under the "TX AUDIO CONTROL PER MODE" tab. Uncheck the AGC and add the gain you need in the blank box to the right of the check box. In my application, I had to push the gain all the way up to a +12.

If you still don't get any TX audio, then you have to flip the setting under the "Advanced" tab, the "AUX PTT AUDIO". There are only 2 selections in this box. Just pick the other one. Can't tell you the correct one as the GREAT MOTOROLA software geeks can't seem to make up their minds with all the software versions they keep trying out on us program testers out in the field. Nothing like using all the radio shops around the country to do your testing for you at no cost.

Jim