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ray_mcavoy · 10-29-2017, 04:31 PM

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.

10-29-2017, 04:31 PM	#8
ray_mcavoy Registered User Join Date: Nov 2009 Location: Sherman, ME Posts: 2,354	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.