Heathkit SG - Printable Version

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Heathkit SG - tab10672 - 07-27-2014

I recently bought a frequency counter to check my heathkit sig gen and although I restored it several years ago and have had no problems with it when I check it with the counter, as long as the output dial on the gen is set on low the freq is dead on but as I increase the output on the gen the frequency climbs on the counter. Shouldn't the frequency that the gen is set to stay the same no matter how much the output is increased?

Thanks, Todd

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RE: Heathkit SG - Ron Ramirez - 07-27-2014

The frequency stays the same...but most signal generators put out a fairly weak signal which is too low to properly trigger the counter unless the output is set to a high level. So when you have the output control on your generator set low, the counter gives an inaccurate reading.

Best way to overcome this is to study the schematic of your generator, then install an output jack wired into the generator circuitry ahead of the attenuator controls, so that its level remains high. Connect your freq counter to this new jack.

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RE: Heathkit SG - codefox1 - 07-29-2014

Yep, count varies with output. Get the old generator (and warmed up mind you,) and modern counter to agree, remove the counter, and hope for the best. Probably still better than relying on the printed dial, and "good enough" for most AM jobs. Your results may vary.

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RE: Heathkit SG - morzh - 07-29-2014

I have no problem using this setup.

You raise the output to read steady value that agrees (more or less) with the SG scale, and then lower it appropriately if needed.
I also turn off the modulating signal while setting the frequency.

And yes, both counter and SG should be warmed up for a few minutes.

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