I have a couple old radios now that I don’t know if they are working or not. I was trying to figure out a reasonable way of testing them, since I don’t have a car to put them in. It is helpful to do it out of the car in the event they need repair, or you want to sell them. They will be worth a lot more in sale or trade if you know they’re working. So I started looking into how I could bench test. There are many ways you can skin this. I found several suggestions of buying a dedicated car battery or connecting units to your daily driver for power. Some people just test outputs on multimeters. I wasn’t really fond of either. Despite very little electrical knowledge, I was able to come up with a ~$20 bench test rig that requires no soldering, no car battery, and no multimeter. While I’m sure a lot of folks could come up with something slicker, I was quite proud when this all worked out.
Parts
- 12v power supply – Needless to say, this won’t work for 6v radio testing
- Primary wire – I used 16 gauge red and black for easy identification
- Fuse holder (optional) – I had this in my tool chest.
- Fuse (optional) – 2 or 2.5 amp fuse is recommended
- Speaker – For older radios 8 ohm will help prevent possible damage. but I think this would only occur over a long period of time.
- Antenna – You might get by shoving a coat hanger in there, but why when you can get a proper antenna with plug for $8
- Banana plugs – For connecting speaker to radio
- Spade connectors x 2 – For power to radio
- Wire connectors (bullet, spade, butt splice, most any will do)
If you buy the 12v power supply I recommend, you will have an easy time with the positive and negative, thanks to the included screw terminal adapter. If you are trying to use a power supply you have around the house, you will need a multimeter to test for positive wire.
The speakers I bought were cheap, small, and 8 ohm. The downside is the wire is very very thin. I was very concerned with breaking them.
Tools
- Wire strippers / crimpers
- Screwdriver
Connections
Thanks to Vintageblau, the connection points on an early 70s radio was easy to figure out. While the speakers to have a red and black lead, I don’t think you can reverse these and cause yourself an issue.
