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+ Ground on MGB

Discussion in 'General Technical Questions and Answers' started by N9GBI, Apr 27, 2005.

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  1. N9GBI

    N9GBI Ham Member QRZ Page

    Want to install 2m rig in 1965 MGB with + ground. I can attach rig to plastic speaker housing, power cord to battery, but what about the antenna? Will mag-mount be ok? or is the best bet a hand-held?

    N9GBI
    [​IMG]
     
  2. WB2UAQ

    WB2UAQ Ham Member QRZ Page

    There are DC to DC converters that you can use to get +12 v above ground from a + gnd system. Do a search on them here on the web.
     
  3. K7FE

    K7FE QRZ Lifetime Member #1 Platinum Subscriber Life Member QRZ Page

    You can also re-polarize the the generator in about two min.  You will need to replace the am/fm radio with a
    -12V ground one, but considering you may want a CD player etc. that may be no problem.

    73,
    Terry, K7FE
     
  4. W7DJM

    W7DJM Banned QRZ Page

    There's more to it than repolarizing the generator.

    First, this may be a classic worth preserving, IE don't hack it up.

    However, if you DID want to convert from pos to neg ground, the coil will have to be reversed, and repolarizing the generator may lead to problems. Many regulators have the chemical/ physical makeup of the relay contacts such that they will only tolerate one or the other polarity. Some replacement aftermarket regulators have the contacts built such that they don't care.

    The gauge's may or may not work reversed, or need to be rewired. The starter, fuel pump, wipers, heater, may not care, I don't know if any of these rigs used permanent magnet fields or (probably) not.

    I'd vote for one of the polarity converters. Having a "great big" piece of equipment above ground in a car is NOT a good idea, and on most 2 meter rigs I'm familiar with, the antenna cable (shield) WILL ground the radio.
     
  5. KB2VXA

    KB2VXA Ham Member QRZ Page

    Hi all,

    If I had a classic MGB I would be having so much fun driving it I wouldn't have time to play radio.
     
  6. K9STH

    K9STH Platinum Subscriber Platinum Subscriber QRZ Page

    Back in college I had a 1959 Triumph 10 Estate Wagon. I was working for Motorola at the time and the parts department had a large number of "exchange" AM/FM car radios that were more than 2 years old (brand new) but were no longer needed for warranty replacement purposes. So, the radios were sold to the employees for $1 each.

    The Triumph 10 was positive ground with a Lucas electrical system. All that I had to do was to reverse the battery connections to make the automobile negative ground so that I could install one of the solid-state AM/FM radios. The only instruments were the fuel gauge and a current meter (which read both positive and negative - center zero). For some reason the fuel gauge worked with either negative or positive ground and the ammeter didn't care since it was center zero. The generator polarized correctly when I started the car and I never had any problems with the electrical system.

    Of course no one "argued" with the Lucas "flamethrower" headlights that came standard on the Triumph 10. If someone "flashed" their lights thinking that I was on "high" beams and I "flashed" right back the other vehicle usually dropped their headlights VERY fast! The reverse was also true, if I "flashed" my lights at a car that had their headlights on "high" they usually dropped them VERY fast!

    Glen, K9STH
     
  7. K7FE

    K7FE QRZ Lifetime Member #1 Platinum Subscriber Life Member QRZ Page

    Like Glen, I changed polarity on a 1968 British Austin that I had bought new in 1968, so I could put an American AM/FM tape in the car. I reversed the battery and started the car. Then I took a clip lead connected to the positive terminal of the battery and touched the field terminal on the voltage regulator. Done.

    All gages and other things worked fine.

    73,
    Terry, K7FE
     
  8. W7DJM

    W7DJM Banned QRZ Page

    ""For some reason the fuel gauge worked with either negative ""

    Many gauge circuits, including the popular Stewart Warner black face gauges, are a bridge circuit, and "don't care" as to polarity.

    If you think your Lucas' were bright, you "ain't" seen my 4537's. (used to be less than 5.00 each)

    Anybody that knows what a 4537 is, knows what it is.
     
  9. K9STH

    K9STH Platinum Subscriber Platinum Subscriber QRZ Page

    I am not absolutely sure, but is a 4537 used for certain purposes in aircraft (like landing lights)?

    I have known some people who used to put lights from aircraft in place of their headlamps.

    Glen, K9STH
     
  10. W7DJM

    W7DJM Banned QRZ Page

    Give the man a prize. First time I saw a pair of those, were installed in K7WWA's 65 Chevelle at Treasure Island, later in my '70 6 pack Roadrunner, having been previously owned by WWA.

    Those things were just great in their day, not bad now, if you can afford them.

    I'll tell ya one thing. You don't get into little arguements about who is going to dim or not.
     
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