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I Love My Landy!
7th December 2009, 04:05 PM
G'day all,

I have got an AM CB radio connected to a speaker in the dash of my County. I would also like to connect a UHF radio to this same speaker. I would like to be able to operate both radios at once. Does anybody know if there is any problem with connecting the wires from the UHF to the speaker at the same terminals where the wires from the AM CB are connected?

Thank you in advance!

Edward :)

mike_ie
7th December 2009, 04:11 PM
From an electronics point of view, as long as both radios use the same speaker type (usually an 8 ohm speaker), then there shouldn't be a problem. If you want to be careful then you can put a diode in the positive side of the speaker connection from each radio, but it's probably not essential.

From a practical point of view, do you plan on running both radios at the same time?? If so, I can see it being very annoying of transmissions come in from both radios at once....

I Love My Landy!
7th December 2009, 04:21 PM
Thanks mike ie!

Well i generally would not be using both radios at the same time, however i was thinking more about problems that may occur if both radios were turned on accidently.

Edward :)

charlesdillon
7th December 2009, 04:44 PM
hi. I agree, from an electronics point of view there would be no problems, but having worked as a strike team leader in the C.F.A. , we can have up to 4 radio's in the one command vehicle, so we generally space each speaker at distance from each other so that you know which radio to respond to. Even still you do get easily confused!

miky
10th December 2009, 08:41 PM
... we generally space each speaker at distance from each other so that you know which radio to respond to. Even still you do get easily confused!

Most radios have a squelch hi/lo line which can be brought out to a timer (555 works well) bringing a small led on.
2 secs works well, but of course you can adjust.

rogan
13th December 2009, 06:45 PM
If you want to be careful then you can put a diode in the positive side of the speaker connection from each radio, but it's probably not essential.
Please don't do this. Speaker signal is sinusoidal and doesn't work like dc current.

mike_ie
13th December 2009, 10:03 PM
Please don't do this. Speaker signal is sinusoidal and doesn't work like dc current.

Indeed. Think my brain must have been switched off when I wrote that :eek:

waynep
19th December 2009, 02:16 PM
I wouldn't be doing it.

There's various reasons - impedance mismatch, possible AC and DC components feeding back into the other amp. You could cook either the CB or your AM radio.

You COULD do it with a properly designed impedance bridge made up of resistors and capacitors, but then that would cost you.

Just fit another speaker.

I Love My Landy!
27th December 2009, 12:13 PM
Thanks again for everyone's replies!

Edward :)