The Ford Barn

nick's41 · 03-12-2020, 07:07 PM

I Have the original Motorola 505 radio that was put into my '41 Ford pickup in late 1947. I had it restored and I need to know the best way to instal it with my newly converted 12 volt Negative Ground system. The manual says it requires 6.3V DC so can put in a regulator to convert from 12V back down to 6V, but..... does the radio case need to be isolated from the truck cab because it used to be on a Positive Ground? It was mounted to the inside of the firewall with 2 "radio hooks" that will ground the case right to the cab. Or did Motorola isolate the radio's chassis to allow installation in either positive or negative ground systems of the day? Anybody have experience with this?

philipswanson · 03-12-2020, 07:19 PM

Most 6v radios run fine on reversing polarity. If in doubt, have an expert look at the schematic.

WABOOM · 03-12-2020, 07:26 PM

You had the radio restored? Ask the guy who restored it.

cmbrucew · 03-12-2020, 08:03 PM

I believe the vibrator is poliarty sensitive. Your tech could tell you.
Bruce

meric42 · 03-12-2020, 09:18 PM

Quote:

Originally Posted by cmbrucew

I believe the vibrator is poliarty sensitive. Your tech could tell you.
Bruce

Modern 'solid state' vibrators are polarity sensitive, the original ones are not.

ford38v8 · 03-12-2020, 09:47 PM

Sponsored Links (Register now to hide all advertisements)

Quote:

Originally Posted by meric42

Modern 'solid state' vibrators are polarity sensitive, the original ones are not.

As I remember from my youth, the digital model I used always pointed south.

03-12-2020, 07:07 PM	#1
nick's41 Junior Member Join Date: Nov 2019 Posts: 1	Original Radio with new 12V Neg Gnd system I Have the original Motorola 505 radio that was put into my '41 Ford pickup in late 1947. I had it restored and I need to know the best way to instal it with my newly converted 12 volt Negative Ground system. The manual says it requires 6.3V DC so can put in a regulator to convert from 12V back down to 6V, but..... does the radio case need to be isolated from the truck cab because it used to be on a Positive Ground? It was mounted to the inside of the firewall with 2 "radio hooks" that will ground the case right to the cab. Or did Motorola isolate the radio's chassis to allow installation in either positive or negative ground systems of the day? Anybody have experience with this?

03-12-2020, 07:19 PM	#2
philipswanson Senior Member Join Date: Oct 2015 Location: Bonita, CA Posts: 1,374	Re: Original Radio with new 12V Neg Gnd system Most 6v radios run fine on reversing polarity. If in doubt, have an expert look at the schematic. Last edited by philipswanson; 03-13-2020 at 10:37 AM.

03-12-2020, 07:26 PM	#3
WABOOM Senior Member Join Date: Jun 2018 Location: Minnesota Posts: 347	Re: Original Radio with new 12V Neg Gnd system You had the radio restored? Ask the guy who restored it.

03-12-2020, 08:03 PM	#4
cmbrucew Senior Member Join Date: Dec 2010 Location: North of sandy ago, CA. Posts: 2,064	Re: Original Radio with new 12V Neg Gnd system I believe the vibrator is poliarty sensitive. Your tech could tell you. Bruce __________________ Works good Lasts long time