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Re: How to become a DPO

Subject: Re: How to become a DPO
From: Eddie Sheffield <>
Date: Sat, 15 Sep 2001 12:24:37 -0400
On Saturday 15 September 2001 11:06 am, wrote:
> In a message dated 09/15/2001 9:31:44 AM Eastern Daylight Time,

> Mostly correct.  The antenna and speakers have to be isolated as you said,
> but the original poster is converting from pos to neg ground and wants to
> use a pos ground radio for originality.  Either buy a NEG ground radio or
> have one converted by someone who knows how.

Hmmm. There seems to be some misunderstanding about this question. Here's the 
original question again, with some comments:

>Now to the question.   I recently acquired a 1962 MGB (#656).  It has been
>changed to a single 12 volt battery but is still wired positive ground.  I

OK, the car is still positive ground. 

>have read about how to convert it but I have this question.  

What kind of conversion? Positive ground to negative ground? Is that what's 
being planned? Or you've read up on the dual to single battery conversion so 
you could understand what's been done so far?

>Radios?  It
>appears they were optional in 1962 but assuming they were positive ground
>where can you find one?  Or is there some kind of converter you can put on a
>negative ground radio to make it work? 

Now it sounds like no conversion is planned and the poster wants to use a 
modern negative ground radio in the positive ground car. This is what I 
assumed was being asked - now I'm not so sure.

Tom, can you clarify what it is your doing?

1) Positive ground car to negative conversion? If you do this you can use 
pretty much any later negative ground radio (British Leyland or not) with no 
problem. If you want to perform such a conversion but use an earlier positive 
ground radio then you'll need lots of careful isolation. I don't know of any 
converters that work for this kind of arrangement.

2) Keep car positive ground and use a later negative ground radio. If so, 
then you'll still need to isolate everything. If you do it right, you 
probably don't need a converter. Even with a converter you still need things 
isolated since the radio chassis will be neg and car chassis will be pos. The 
converter I believe also acts as a regulator, and is good if you have, say, a 
pos ground 6 volt system but need negative ground 12 volts for radio.

3) Keep car positive, use early positive radio. Easiest solution - drop right 
in. Just have to find one. Try MG classifieds and ebay and of course, this 

Sorry that's kind of long. Just trying to figure out exactly what's being 

1971 Midget

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