The Stovebolt Site Forums The Shop Area The Electrical Bay The Radio Bench Finally going to wire my radio.

I think I will run power from the ignition switch. I believe there is an accessory post on it. How do I determine which post that is? Can I use a test probe to check it?

Yes

Check which post is hot when the key is off.

If it is hot that means there is always power to it. If I should leave the radio on it would drain the battery would it not? I do not see me leaving it on as I do not plan to use but it would be nice to be working.

That is correct.

You could connect to an "accessory" lead/post that is off when the ignition switch is off. Check for the post that meets that requirement.

Will do. Not too many posts on the switch I don't believe.

Do you have an original 1949 truck ignition switch?

How many posts does it have on the back of the switch?

It is an original 1949 switch. I do not know the number of posts as I cannot get it out very easily. Somewhere I thought there might be 3 as that is what is shown on the schematic.

My switch on the 51 does have three terminals. The original instructions for the radio installation call for the radio to be wired to the always hot feed to the switch. I believe this is because the switch wasn't rated to take the ignition, heater and the radio at the same time.

Thanks Fred. When it comes to the radio bench we can count on you. I think I tried to remove the ignition switch once before but had difficulty with the bracket attaching it to the lower dash.
So given your comment that post on the switch would be a stand alone with nothing on it now. And it would be hot when the ignition is turned on?

There is a wire that goes from the ammeter to the ignition switch. That wire is always live so that is where you would want to attach the feed if following the original instructions.

Thank you. Now being always live would that mean if I left the radio on for an extended period of time I could drain the battery?

That is correct.

I believe the original installation kit had a fuse holder that actually threaded onto the stud of the ammeter so that it was completely protected from the source. I don't think anyone reproduces those.

Thanks. Never seen them either. But of course I never looked as I didn't know of them.

The inline fuse holder is a slightly different version of this. They are a hard Bakelite that was prone to overheating and cracking few survive other then NOS.
https://www.flickr.com/photos/advance-design_parts_co/8129302395/in/album-72157631868452754/

seen something similar but not for a car radio.