Batboard

I have a CDM 1250 Vhf mounted in a 96 e-350 diesel that has recently started to emit 2 chirps similar to the low battery chirps on a Moto portable when transmitting. The radio does this intermittantly when keying the mic. The radio will tx for a second then drop out.

I'm guessing it is a power supply problem but I can't figure where from. The radio is set to follow ignition and the ig. sense is piggy backed to the 12VDC main line because it is a switched source. This problem has just started, the radio has been installed for three years. Any ideas?

Well is sounds like from your description who wired it up installed it so that the main power goes direct to the battery/or to a power pole location under the hood and the ign sence is wired to a swiched or how ever u want to wire the ignition sense.

also how old are the batteies. when my batteirs were on the way out my did the same thing

also check the alternator

It is installed in an ambulance with a Cole Hersee battery switch that kills all of the vehicle power.

The batteries are 5 months old. There is a Spectra that is installed on a different circuit that has no problems tx'ing.

I'm just curious if it is a problem with the radio or the power supply lines.

i have NEVER heard of a CDM doing a PRO series lo battery chirp. this is strange. even for an undervolt. I've had CDMs do everything short of fold the laundry and lock on TXmit, but never heard a Pro-series lo-battery chirp.

Trust me, they do. Just saw it this week. Sounds like a Jedi low battery chirp. Batteries in the truck were low, and it exhibited this behavior on transmit.

commtek wrote:Trust me, they do. Just saw it this week. Sounds like a Jedi low battery chirp. Batteries in the truck were low, and it exhibited this behavior on transmit.

Potentially a firmware-specific issue?

... you can have the radio sense for voltage and adjust the radio to operate according to it so as not to drain your battery or something like that ... chances are it is sensing the battery is crapping out and adjusting accordingly ... it is emitting the beep to let you know it is running in that mode ... i may be wrong though since i have never seen this first hand ... the cdm's i have worked with will just shut off and then back on when the power is too low for a transmit

Put a volt meter on the power source and see what it's doing at standby and at TX. That should give you a pretty good indication if it is a low voltage problem. Just because a batter is new doesn't mean you're getting correct voltage.