James
If you really mean loudspeaker, then simply connect a buffer resistor,
about 33 ohms should do it, in series with each radio output, on the hi
side, then connect their junction to the speaker hi. Common the lo
connections.
If you mean headset phones, then adopt the same principle, but use about
470 ohms.
Incidentally, many radios have an auxiliary input. A more elegant solution
to your problem is to allocate one radio as the master, with its output
connected normally, and the second as slave, feeding into the auxiliary
input of the first. That way you hear both radios. Check the handbook to
make sure you don't exceed the maximum input signal on the aux. input.
(Usually a few hundered millivolts).
Good luck.
Dave Simpson #47 (and still no top on)
----------
> From: James Naylor <jnaylor@avnet.co.uk>
> Subject: Audio mixer
> Date: 12 October 1998 08:51
>
> A question for the radio experts out there.---
>
> I want to connect two radio's together so that I can switch to either for
> transmit and receive, with the option to receive on both. I know audio
> panels are available commercially, but they usually contain Markers ADF
etc
> which I do not need, not to mention the cost.
>
> The only problem I have encountered, is feeding the two audio outputs
into
> one speaker at the same time. Some form of isolation circuit is required
> to prevent the two radios trying to drive each other backwards, so to
> speak.
>
> I'm sure there must be a simple design that could be built into a small
box
> with just one switch for selecting the radio (I have got this far) and
one
> to select the speaker for both or individual.
>
> Any help would be appreciated.
>
> Jim Naylor
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