Thread: what UHF set works best

Originally Posted by JDNSW

I have tried both direct from battery and via ignition. No difference in performance, but I have had flat batteries on quite a few occasions as a result, particularly with vehicles that are not regularly used. My 2a is now wired both ways - with a changeover switch so you can switch on the radio with the ignition off only when you really need to, but normally leave it on the ignition position.

John

Speaking of 2a's, are there any positive earth UHF sets around? I guess it's probably easier to convert the vehicle to neg earth.

Originally Posted by dm_td5

Battery drain from a CB UHF is minimal when left on, even when receiving. In the case of the IC-440 its listed as Rx (standby) 400mA and Rx (max audio) 1500mA.

Of course, the current will increase quite a bit whenever you transmit. Sometimes if you tap off an iginitio switched wiring, the wiring will not be heavy enough, and the voltage at the radio will drop when you transmit. This will cause a drop in transmit power or possibly even distorted transmissions.

If you really wanted the radio to go off and on with the ignition, I'd be suggesting you still wire the radio power direct to the battery but switch it via a relay from the ignition. ( similar to the setup for driving lights. )

Some UHF sets have an "ignition sense" wire that is basically does the same thing.

Originally Posted by dm_td5

Battery drain from a CB UHF is minimal when left on, even when receiving. In the case of the IC-440 its listed as Rx (standby) 400mA and Rx (max audio) 1500mA.

Of course, the current will also increase quite a bit whenever you transmit. ( I see for the IC-440 Tx current draw is listed as 2 amps which is better than the old 400 which was spec'd at 4 amps ).

Sometimes if you run the radio off an iginition switched wire, the car's wiring will not be heavy enough, and the voltage at the radio will drop when you transmit. This may cause a drop in transmit power. It would be hard to detect unless you put a power meter in the antenna line, but it would reduce your range a bit. ( sometimes might cause distortion or buzzing on your transmission too ).

Some UHF sets have an "ignition sense" wire that means you can wire the main power lead to the battery but switch the radio off from the ignition. The old 400 had this option via the accesory connector, I am presuming the 440 has it too.

great advice as usual. thanks fellas.