Pm 1500 simulcasting problem

[BENWSI]

O.k., guys, I need help. We've installed several dual con. head PM1500's for an ambulance svc., and for the most part, no problem. BUT, we have one unit that is transmitting on two freqs. at once. One of our better techs went over it with a fine tooth comb, and found nothing. He pulled the transmitter, we shipped back to Moto and they found nothing. What now Batman?

Ben

[escomm]

Transmitting on two frequencies at once-- Can you elaborate on this? How have you determined it's transmitting on two frequencies at once? Do you know the second frequency? What is the firmware version in the radio?

[BENWSI]

Transmitting on two frequencies at once-- Can you elaborate on this? How have you determined it's transmitting on two frequencies at once?

It is the two EMS freqs our Ambulance customer uses. They typically do all their radio traffic on one channel, but a dispatcher happened to catch the phenomena while it was happening. Again, it only happens to one vehicle.

Do you know the second frequency? What is the firmware version in the radio?

The firmware version is the most up to date. We've kept up on all of that, (I don't know the version off the top of my head, it's in my laptop.)

We got the original transmitter back from Moto and I put it back in the vehicle today, VOILA! No problem. BUT, this does not tell us why it was doing it.

Still looking.

[jackhackett]

Possibly it was spurious due to a loose connection which was cleared up when it was put back in.

The radio will only transmit on one channel at a time no matter how many control heads or what firmware, it has one synthesizer and that will only generate one frequency at a time.

[BENWSI]

Possibly it was spurious due to a loose connection which was cleared up when it was put back in.

The radio will only transmit on one channel at a time no matter how many control heads or what firmware, it has one synthesizer and that will only generate one frequency at a time.

I know, but it was coming in on both freqs just as clear as a bell. For the record, those freqs were:

155.305
155.750

[escomm]

Again, I will ask-- How do you know it was transmitting on both of these frequencies at the same time? Did you use a spectrum analyzer??

[Motoboy]

What is the receiving equipment in dispatch? It wouldn't, by chance, be a T22R station, would it?

[BENWSI]

Again, I will ask-- How do you know it was transmitting on both of these frequencies at the same time? Did you use a spectrum analyzer??

Sorry for the delayed response, yes, our tech did use a spec. analyzer and commented that it had a "high noise floor," and a spike on the alt. freq.

Home freq: 155:75
Alt. chan: 155.205

The base at the amb. svc. is an MTR3000.

[BENWSI]

What is the receiving equipment in dispatch? It wouldn't, by chance, be a T22R station, would it?

It's an MTR3000