Voltage below 13v causes radio to reset.

[alannerd614]

Good afternoon to all,

So here is what I am running into on 2 radios so far:

They are 800 MHZ XTL 2500. Flashed with 96/36 inter, ADP (not that it matters, but just in case someone asks). They are operating on a 7.4, 4 site, simulcast system.

I have this radios that will shut off arbitrarily. I have put them on a bench adjustable voltage / amperage power supply for testing and I find similar issues on both.

When I have the radios at 13.20 volts or above, the radio performs fine. Keys, etc...

When the radio is below 13.20, and I key the radio, it cause the radio to drop the voltage down to around 8 volts, then back up to 13 when it stops keying. The amperage also spikes, like expected, as it keys.

This causes the radio to reset.

Any thoughts / comments?

[akardam]

Sounds like the radio is drawing way more than it should be (or your power supply isn't capable of providing the necessary current). Max TX current draw on an 800MHz XTL should be around 12 amps. With your supply set at 13.8v, measure the current draw of the radio when it's keyed.

[Jim202]

As AKARDAM has said, you need to look at your source voltage. The newer radios have voltage regulators in
them that don't like low voltage. If you have a strong bench supply (30 amp) and the voltage is still dropping
at the radio, I would look at my wiring and or any fuses that might be inline.

You didn't say if the radios are doing this in a vehicle install. If this is going on in a brand new vehicle install,
you need to test the vehicle battery voltage and the vehicle load voltage. With the engine running and the
headlights and heater or A/C on, measure the voltage on the fuse block under the hood. Also at the same
time measure the battery terminal voltage. If the battery is using top battery posts, this is even more important.
When you measure the battery terminal voltage, use the top post itself and not on the cable clamp.

Reason I say the battery post and not the clamp, I have seen brand new police package vehicles have very
poor connections right at the battery post. I have been surprised they were even able to start the engine.
Cleaning of the battery post solved the problem. The way I found it way there was very high alternator
wine on the radio transmission. The headlights went real dim during the transmission. After cleaning the
battery terminals and the battery post, problems gone.

You haven't told us yet about the vehicle, I am just giving you a heads up.

Jim

Good afternoon to all,

So here is what I am running into on 2 radios so far:

They are 800 MHZ XTL 2500. Flashed with 96/36 inter, ADP (not that it matters, but just in case someone asks). They are operating on a 7.4, 4 site, simulcast system.

I have this radios that will shut off arbitrarily. I have put them on a bench adjustable voltage / amperage power supply for testing and I find similar issues on both.

When I have the radios at 13.20 volts or above, the radio performs fine. Keys, etc...

When the radio is below 13.20, and I key the radio, it cause the radio to drop the voltage down to around 8 volts, then back up to 13 when it stops keying. The amperage also spikes, like expected, as it keys.

This causes the radio to reset.

Any thoughts / comments?

[alannerd614]

No thank you both. Very good ideas.

They were both in '02 CVPI vehicles.

We are just finding this so we havent had an opportunity to test the vehicles just yet, as they are out on the streets. However, I will do so ASAP.

And just FWIW, we had hot going straight to battery term, neg on frame, and soft power off switch.

[alannerd614]

With your supply set at 13.8v, measure the current draw of the radio when it's keyed.

It starts at roughly 8.25 and after holding it for 30 seconds it was steady at roughly 9 amps.

[Winger2002]

Ship it to the depot, have had a few xtl's with this issue, cant remember what the problem was but its firmly in M's court.

[ka8ypy]

Just out of curiousity, what gauge wire are you running from the radio to the battery? I had a department that had this happen out of the blue with a couple of cruisers, the culprit was under rated wiring, if the wiring is sufficient, then as stated above, punt them back to Motorola.

[alannerd614]

Yea its actually Motorola wiring straight from a box.