I have the opportunity to get a hold of a couple of HP Signal Generators

[Polaraligned]

Originally Posted by vortalexfan

Well I picked up the HP HP 8640B on Wednesday and I got it home and hooked it up to try it out and it doesn't seem to be wanting to put out a test tone (400 hz or 1kHz tone) ar the frequency dialed in on the frequency readout (for example I tried to dial in .45500 MHz on the readout or 455 kHz), and when I tried to tune to the low end of the AM band on a known working AM radio the test tone couldn't be heard and neither could the RF signal unless I went up almost 35 kHz on the readout on the signal generator.

Any ideas as to what's going on here? Is my radios IF Freguency that far off or is there something wrong with the calibration of the signal generator?

What test equipment do you have at your disposal? An oscilloscope and frequency counter would be nice. Maybe modulation is not working? How are you coupling signal into radio? The readout on these is just a frequency counter as they are not synthesized, so the internal cavity oscillator is working, but you still may not be getting output if the attenuator is not working. It is just hard to say from what you are describing without trying to look for signal output on oscilloscope. These are very difficult units to work on as is ALL HP equipment. If you are not experienced with these it may just be better getting a working unit. Did your friend say the unit was working? You NEED the service manual to repair these. HP has flow charts for troubleshooting, but that also requires test equipment to do so.