In a message dated 1/5/99 12:57:39 AM Eastern Standard Time, vafred@erols.com
writes:
> > Meanwhile, I assume you're aware of the rather simple procedure for
> > changing your system to negative ground using your existing generator,
> > starter, etc. BTW, I use a negative ground stereo in a positive ground
> > car -- was really fairly easy to isolate the unit and antenna from the
> > body.
> >
> > Geo Hahn
> > 59 TR3
>
>
> George, just for future info, how do you isolate the radio and what does
> the antenna have to do with polarity as well as the starter ???
Fred and George,
George is correct, but there are a couple of things that need to be
considered.
1) There is a bit of a hazard associated with using a negative ground radio in
a positive ground car. In almost all instances, the case of the radio is at
ground potential. With a negative ground radio in a positive ground car, there
is 12 volts between the radio case and the car chassis. You can isolate the
case from the car chassis, but unless you insulate the radio case, you must
exercise great caution when working under the dash not to let your screwdriver
or wrench - or watch band for that matter - come into contact with both the
radio case and the chassis. Maximum sparks - great for the 4th of july, but
not very welcome under the dash! It can certainly work, but just be careful.
2) The efficiency of the radio antenna will be dramatically reduced. Maybe
some of the Ham radio operators on the list can explain this better than I
can, but a car antenna relies on the sheet metal of the car to act as a ground
plane, improving the range. It will work without this ground plane, but not as
well. You can, if you want, just stick a piece of wire into the antenna
socket, let it hand down in the floorboard, and it will work quite well in a
strong signal area, but out in the country, away from the stations, you will
find your reception less than with a correct antenna installation.
To my way of thinking, an antenna that doesn't work very well is much
preferred to one that does. In fact, my ideal antenna is one that doesn't work
at all, so there is absolutely no chance that I'll ever have to listen to a
radio station! Most folks, though, feel differently. One of the things that
frustrates me no end is that I can't buy a tape/CD player without getting a
radio, and I can't buy one with a radio without getting the feature know as
"tuner recall" that plays the radio when the tape is rewinding. Grrrrrr! Do
any of you Hams out there know how to add an NPR or a PRI filter, such that
those are the only stations my radio will pick up? I love music, all kinds of
music, but I HATE, DESPISE, LOATHE and DETEST commercial radio stations!
Dan Masters,
Alcoa, TN
'71 TR6---------3000mile/year driver, fully restored
'71 TR6---------undergoing full restoration and Ford 5.0 V8 insertion - see:
http://www.sky.net/~boballen/mg/Masters/index.html
'74 MGBGT---3000mile/year driver, original condition - slated for a V8 soon
'68 MGBGT---organ donor for the '74
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