Heathkit SG-8 Signal Generator

[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.