Knight KG-652 RF Sweep Generator Repair Journal
By Chad Hauris, Retro Electronics and Audio Lab, Midland, TX. 6/18/2006

This RF generator was kindly given to us by a man in Odessa. We did some preventive maintenance by replacing old capacitors and diodes and adding a fuse to the power line before putting it into service. This unit generates an FM signal by using an inductor that is mechanically coupled to a speaker cone which is fed with a 60 hz signal.

When the speaker cone vibrates it moves the inductor which causes the RF carrier to deviate at a 60 hz. rate from its center frequency. This signal will thus produce a 60 hz. tone in an FM receiver. It comes in very handy for troubleshooting FM IF transformer problems when the generator is set to the FM IF frequency of 10.7 mhz.

Please click the pictures for larger views.

Knight RF Sweep generator chassis
Chassis view. You can see the speaker modulator setup at the left.

Knight RF Sweep generator chassis before repairs.
Chassis before repairs.

Knight FM generator after repairs.
Chassis after repairs with new capacitors and fuse.

Knight FM generator finished.
Completed unit.

Testing a Silvertone radio chassis with the Knight FM generator.
Testing a Silvertone radio chassis with the Knight generator (at top). You can also see at bottom our Heathkit FM stereo generator and Triplett AM generator. Using the Knight FM generator, we found a bad IF can in this Silvertone in less than 20 minutes.

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