Heathkit SG-8 Signal Generator

[Electronic M]

Zero beating: ever run 2 am radios at once and tune 1 through the band and find a point where they both squeal despite not having touched the one you weren't tuning? That's the local osc zero beating with the osc or station of the other set... In Toulouses example you would tune the Chrystal osc to the frequency of the station and listen for the zero beat then tune for minimum signal on the S-meter (exact frequency zero beat).

[vortalexfan]

Originally Posted by Electronic M

Zero beating: ever run 2 am radios at once and tune 1 through the band and find a point where they both squeal despite not having touched the one you weren't tuning? That's the local osc zero beating with the osc or station of the other set... In Toulouses example you would tune the Chrystal osc to the frequency of the station and listen for the zero beat then tune for minimum signal on the S-meter (exact frequency zero beat).

Ok, I get it now. So then somehow I would basically have to somehow tune the crystal oscillator in the frequency counter to the same frequency as the 10 Mhz signal of WWV in Colorado. And then tuning a shortwave radio to that same frequency and adjust the oscillator in the frequency counter until they cancel each other out in a sense on a tuning meter?

[Electronic M]

Originally Posted by vortalexfan

Ok, I get it now. So then somehow I would basically have to somehow tune the crystal oscillator in the frequency counter to the same frequency as the 10 Mhz signal of WWV in Colorado. And then tuning a shortwave radio to that same frequency and adjust the oscillator in the frequency counter until they cancel each other out in a sense on a tuning meter?

Yup.

[vortalexfan]

Originally Posted by Electronic M

Yup.

OK, got it.

[vortalexfan]

OK so I got my parts in to get my signal generator fixed up the rest of the way (BNC Jacks and a new set of cables for it so I could hook it up to a radio), and I got it all wired up and I went to test it out on an old Zenith Royal 500 Transistor Radio I had laying around and I couldn't get the signal generator to do anything, it wouldn't put out a tone or a signal to the radio or anything, I'm assuming with a transistor radio you don't need a capacitor inline with the test leads like you do an AC powered set.

Also I got tons of line interference through the signal generator similar to the line interference I said I had been getting on my radios.

I had my test probes hooked up the RF output jack which I'm assuming that's the hookup I was supposed to use to test the generator out on the radio.

any ideas as to what the problem could be?

[Notimetolooz]

Originally Posted by vortalexfan

I'm assuming with a transistor radio you don't need a capacitor inline with the test leads like you do an AC powered set.

Also I got tons of line interference through the signal generator similar to the line interference I said I had been getting on my radios.

Do you have a copy of the manual?
http://pdf.textfiles.com/manuals/SCA...thkit-SG-8.pdf
You should have a manual for all your equipment.

If you look at the schematic you will see that the RF output does not have any DC blocking capacitor, therefore if you connect it directly to the a point in the radio that has any DC voltage on it that point will be connected to ground through the resistors in the generator output circuit. When in doubt use a external capacitor.
Also the two capacitors in the generator that are connected to the power cord and ground can put a 60 Hz signal on the case. With a battery powered radio the ground connector of the RF cable needs to connected to the radio. A small capacitor in the signal line to the radio will block the 60 Hz but pass the RF. If you use a coupling loop on the generator output you don't need the capacitor.
Another thing, I added a 0.01 uf capacitor in the generator between the wiper of the output pot and the output switch pin 7. There is a DC current running through the output pot from pin 3 (cathode) of the 12AU7. This can cause a DC voltage on the output.