New life to old radio?

[John_Mc]

I have an original British Motor Corporation radio that came with my TR6 (though not installed) as well as an aftermarket MetroSound Radio/Cassette player that was installed and semi-functioning when I got the car, but has been out for a long time. I thought I'd check and see if either still works and maybe install one. I hooked up the radios to my 12V charger (on 2 amp slow charge) and hooked up alligator clips for speaker wires to the speaker. On both radios all I heard was a low monitone hum that didn't change as I scrolled through the stations. I did not have any antenna connected. Now, I know very little about electronics. I can use a voltmeter, but as far as amps and ohms and faradays and giga-hertz and neutrinos I'm pretty clueless. So, first of all, should what i did have worked if the radios were still working? And if not, what should I change? Thanks for any and all advice, suggestions, and comments.

 

[TR3driver]

Very unlikely it would have worked, even if the radios were functional.

Try again, using a battery (not a battery charger) and an antenna. I'd also suggest a fuse in one of the battery leads, in case something goes wrong.

If you don't have access to a car antenna, you can "make do" with a few feet of ordinary insulated single-conductor wire. Skin back the insulation for 1/2" or so, and insert it into the center contact of the antenna connector. Depending on the size of the wire, it may work better if you fold back the bare part and insert both the bare part and the end of the insulated part. Anyway, it needs to make reasonably firm contact with the center terminal, and the bare part has to not touch the surrounding metal. That should be enough to pick up at least a few strong stations.

FYI, battery chargers generally do a very poor job of converting the AC input from the wall into DC to go to the battery. Their output is usually a mixture of DC and AC, which is fine for charging batteries but not so good for running radios. If you want to do this kind of work on a regular basis, you should look for a "battery eliminator" or "12v DC power supply". But for occasional use, a car battery should do fine, as long as you are careful not to short it.

 

[dklawson]

As Randall said, you will need something to be an antenna. I have improvised using anything from the wire he mentions to coathangers with the varnish scraped off one end.

However, I have used battery chargers to power radios... at least for testing. They will work, but even a good one will introduce "hum". You wouldn't want to use it for long since that hum becomes annoying, but it's OK as a quick test for functionality. As Randall said, battery power is much cleaner.

 

[Tinkerman]

I was able to get a "returned" battery from my local auto supply store and that's what I use for all of my testing needs. I keep it up to snuff with a "float charge" from Harbor Freight. I tried the battery charger when I was testing my horns and got lousy to no results so I set up the battery. The auto supply guys were helpful when I told them I needed to test stuff for my TR3 they did not charge me for the battery.

Tinkerman

 

[tdskip]

So it sounds (sorry for the pun, couldn't resist) that you have a shot that it is actually working here John. Next step, remove the circlip and then smash it on a wood block to get the piston out. Oh, wait, that doesn't sound right....

Did you try hooking up a makeshift antenna?