Most car radios also have the antenna grounded both at the antenna mount
and at the radio.
I once saw an MGA catch fire because it had the "cross-wired" solution
suggested by Trevor ! (no fuse in the hot wire, ala British tradition <g>)
The internal conversion should be possible, but difficult. You will need
to provide DC block in the antenna connections and from the circuit board
ground to chassis ground. Probably also a high resistance DC bleed to
remove any static buildup from the antenna.
Converting the car to negative ground is much easier !
Randall
On Tuesday, March 02, 1999 5:26 PM, Trevor Jordan
[SMTP:tjordan@vic.bigpond.net.au] wrote:
>
> At 10:56 AM +1100 3/3/99, Zempel, David W wrote:
> >Does anybody have any notes on converting a negative ground TR radio to
> >positive ground? My '63 TR4 came with a POC aftermarket radio which I
> >removed when I started my restoration 18 years ago. I've since obtained
a
> >real Triumph radio (negative ground) that I hope to convert.
>
> It would be very dificult to convert a radio internally. One solution is
> to completely insulate the frame of the radio so that the polarity of the
> radio is no longer important. The ground wire can then be connected to
the
> battery and the battery wire to the ground. However, it is not easy to
> insulate a large lump of metal like a radio; particularly when it has to
be
> solidly mounted to the dash. The frame would still be positive and it
> becomes a potential source of short circuits in a negative ground
> environment.
>
> I would suggest that it is simpler to convert the car to negative ground.
> This has the added benefit of eliminating the problem forever.
>
> As far as originality is concerned, if you have a real Triumph radio with
> negative ground, it probably came from a later model. If you want to
keep
> the car original, try to find an earlier positive ground radio (or
> reproduction).
>
> Trevor Jordan
> 74 TR6 CF29281U
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