Testing radio
 

I've had a old radio given to me along with the speaker. It has "GM" on the front and is AM only. I'd like to test it before I put it into my 72 C-10. How is the best way to test a radio out of the vehicle. The dial along with the push buttons work.
Thanks,
Bill

Re: Testing radio
 

I'm looking at a truck AM radio and it says, don't operate w/o an 8-10 Ohm speaker. Electrical connections appear to be 12V, ground and speaker.

Re: Testing radio
 

I have two spare radios with three sets of knobs and have not tested them yet.
I would guess power it up, plug in antenna and add speaker should do it...

Bill

Re: Testing radio
 

Is the speaker Ohm rating that important? Maybe long term but for testing I think anything should be fine.

Re: Testing radio
 

Absolutely not. Don't turn on or power up radio without proper ohm speaker. The output coil in the radio will fry within a 1/2 sec.
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Re: Testing radio
 

I have the speaker that came out of the Blazer the radio came out of, they go together.
Thanks for all the help folks.

Re: Testing radio
 

If this is true, I have blown many radios in my life! Crap!!

Re: Testing radio
 

Start by checking the speaker with an ohmmeter. The DC resistance will be a little bit less than the nominal 8 to 10Ω impedance so don't worry if you don't get that exact reading on your meter. You just want to make sure it isn't short circuited (zero Ohms) and that it is not open circuited (infinite reading, which would be the same as operating the radio without a speaker).

If your speaker checks out okay and still has the factory 3-terminal plug, simply plug that into the radio (it should be keyed so it will only fit one way). The empty/unused terminal in that plug is the +12V feed to the radio. Connect that through a fuse to the positive side of a 12V DC power supply or battery. Then connect the negative side of the power supply or battery to the metal case of the radio. Finally, plug in an antenna, turn the radio on, and with a little luck it should come to life. It's not uncommon for the volume & tone controls on these old radios to be a bit dusty & dirty so expect some popping & crackling noises as you adjust those controls. Spraying them with a little bit of cleaner (I use Caig DeoxIT F5) usually cleans them up and gets rid of the noise.

Re: Testing radio
 

true story.. I received the same warning from the owner here [forget who is who]

http://www.turnswitch.com/speakers.htm
vintage speakers Greg / Dan 877-780-2861

although many of us may have been lucky, no need to press our luck if we know better now, right?

turn switch does sell the correct speakers btw and they can answer many of your old radio questions..

good luck!