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Author Topic: Sharing speaker on 3 mobile rigs ok ?  (Read 580 times)
G7IVJ
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Posts: 83




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« on: April 10, 2010, 06:00:18 AM »

Hi everyone

Thanks for the help in advance.

Just installing three radios in the car - dedicated HF radio, 2&70 FM only radio, and 70mhz 4metre FM radio

(70mhz is a band we are allowed to operate on in the UK and some countrys in Europe - becoming quite popular over here)

Instead of having three seperate extension speakers - can I use one speaker, and simply solder onto the speaker contacts two extra sets of speaker wires with the 3.5mm jack on ?

And therefore plug three seperate radios into one speaker and importantly listen to all three at once ?

I am just curious and dont want to do this if it could cause damage to the radios ?

Any comments pls ?

Thanks - Simon
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K0BG
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« Reply #1 on: April 10, 2010, 06:11:17 AM »

It isn't that simple, unfortunately. However, if you buy an amplifier mobile speaker, you can sum the input easily with just a few resistors. Ten ohm ones across the speaker leads and perhaps 10 k ohms in series with the input of the amplifier. By the way, W&S sell the MFJ amplified speaker.
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AA4PB
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« Reply #2 on: April 10, 2010, 06:34:49 AM »

Alan is right. You can't just simply parallel the outputs of the three radios. If you did that, the output voltage of one radio would be feeding back into the output circuit of the other radios. At a minimum it is likely to cause distortion and quite possibly cause damage to one or other of the radios.

Assuming that you want to run more than one radio at a time, the only solutions are to sum and amplify the outputs as Alan described or to use separate speakers.
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Bob  AA4PB
Garrisonville, VA
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