02-10-2013, 05:36 PM
Not sure your question was answered, but there are tons of old Heathkit and Eico, etc... signal generators on Ebay, or whatever, that shouldn't cost more than $30 or so delivered. If you get one, you should treat it as an antique radio, change the filter and paper caps and any out of range resistors. Install a 3 prong cord, check your bench supply to make sure all is right, and lose any caps from line cord to chassis on the instrument.
Now get a modern digital frequency monitor, which you should be able to get for $20.00 or so, and you will be all set for AM radio work. Let the signal generator warm up for at least 30 minutes, then use the frequency meter to verify unmodulated signal generator output, disconnect the frequency meter, and restore modulation. Now you have pretty good means to do alignment. I like an analog AC voltmeter or VTVM across the secondary of the Audio transformer (with shunt resistor of say 4 ohms if you don't want to hear the noise.) A digital meter to peak during alignment will drive you crazy(ier.)
Usual warning, absolutely always use isolation transformer on AC/DC sets. Correctness of AC sockets in most places is sadly still not reliable.
Now get a modern digital frequency monitor, which you should be able to get for $20.00 or so, and you will be all set for AM radio work. Let the signal generator warm up for at least 30 minutes, then use the frequency meter to verify unmodulated signal generator output, disconnect the frequency meter, and restore modulation. Now you have pretty good means to do alignment. I like an analog AC voltmeter or VTVM across the secondary of the Audio transformer (with shunt resistor of say 4 ohms if you don't want to hear the noise.) A digital meter to peak during alignment will drive you crazy(ier.)
Usual warning, absolutely always use isolation transformer on AC/DC sets. Correctness of AC sockets in most places is sadly still not reliable.
