Batboard

I have a customer that has an issue were the XTL5000 (Remote Mount) PTT's when the Federal Q is used. I have narrowed it down to the radio itself as it does have a Firecom attached. I fixed it a few years ago with an inline power filter on the radio but it seem to be acting up again. One of the local Fire truck builders recommended a "switch back solenoid" on the Federal Q. Has anybody heard of this before or experienced this issue?

Could be the vehicle batteries are getting weak, those Qs draw a lot of current.. rated at 100A.

I have seen noise triggering through the Firecom as well.

Batteries are a good thought though

Unhooking the Firecom radio interface / intercom yielded the same results.

Have you measured the 12 volt line feeding the XTL when the siren is lit off?

Low voltage can cause wired problems.

When you said you unhooked the Fire Com / intercom, are you saying the accessory connector was pulled from the XTL? Trying to see just what is left connected to the radio to help with ideas on your problem of the radio going into a keyed (TX) condition if I am understanding your post correctly.

Jim

Hi Jim,

I unhooked the radio interface at the Firecom intercom gateway. I haven't gotten into any deep troubleshooting as of yet. I was just looking to see if anybody else had seen this issue as it's a fairly common setup.

Ive seen a real deal airhorn do this in a fire engine. No solution I've found.

Ran into the exact problem with an XTL2500 remote mount. We had the firecom unit wired to the acc port on the control head. Moving the firecom interface to the db25 on the transceiver fixed the problem. I believe Firecom has a special cable to resolve the issue now.

I would try disconnecting the Firecom cable from the radio end. I don't see how having the cable on there but disconnected would still cause the problem unless the siren was emitting RF, but if you take the cable off completely that should rule out the Firecom. You might also try disabling the PTT input that the Firecom is using in the radio programming if that's possible.

I'm still suggesting to check the vehicle batteries. If a power line filter solved the problem before then it's probably noise on the power feed causing it. Batteries act like a giant capacitor, filtering the DC voltage from the alternator. As they age their internal resistance go up and they don't filter as well, much like a capacitor with a high ESR.

One other thing to consider might be a power line conditioner that filters and adjusts for voltage surges and drops.