Batboard

I recently installed a MCS 2000 dual head setup in an Ambulance. When the engine is not running, the front and rear speakers have a terrible squeal in them. The squeal is also in a Kenwood portable and a Minitor IV pager. We located the source ,it appears to the control boards mounted in a cabinet about 3 feet away.

The interference can be heard in the pager and portable outside the vehicle. When the engine is startted however, the MCS works fine on transmit and receive.

Any ideas?

JD wrote:I recently installed a MCS 2000 dual head setup in an Ambulance. When the engine is not running, the front and rear speakers have a terrible squeal in them. The squeal is also in a Kenwood portable and a Minitor IV pager. We located the source ,it appears to the control boards mounted in a cabinet about 3 feet away.

The interference can be heard in the pager and portable outside the vehicle. When the engine is startted however, the MCS works fine on transmit and receive.

Any ideas?

I would look at how all the power wires are run to the radio.

Secondary to that - install another MCS2000 radio in it, and see if it produces the same noise, and also, install the MCS drawer in another truck and see if the noise follows the drawer or the truck. If it follows the drawer, I would suggest sending it back to Motorola for warranty or flat rate repair.

-Alex

We had the same problems with ours, come to find out it was the inverter/charger that was making the noise. When the truck was turned off and plugged into a shore line the problem was there, when the truck was started the automatic spit-off would disconnect the shoreline and the problem was gone. Replaced onboard inverter/charger and problem disappeared.


Mikey

That is exactly the same conditions we are having. At first I thought it was in the MCS, I have had several issues with them over the years. However, the portables and pagers are picking up the interference 3 to 5 feet from the ambulance.

Another question, does it make much difference if the transceiver is mounted behind one of the seats in the front or a compartment in the back ? Usually the units electronics are in the patient compartment, but mounting in the rear or behind the seats is about the same distance.

I have seen both ways.

I don't think it matters were you mout the RF deck, it will still interfere if the Inverter/Charger is the problem. We had our RF packs mounted behind the drivers seat against the wall, tried moving it to the passenger side behind seat and still had the same problem. We took out the inverter and called the company that manufactured it and told them what was going on and they were nice enough to send us a loaner inverter to use while ours went back to them for repair.

I had a problem sort of like this with an MCS in an ambulance, it wouldn't transmit when the generator was on. Seems it was getting noise on the power leads that disturbed the radio's micros.