philip harris signal generators - old style

Hi. I have two of the older style philip harris signal generators (blue and silver) and both are misbehaving in the same manner. You select different ranges of frequencies by turning a knob, some of the frequencies overlap between different ranges - e.g. one range is 0.7 kHz - 10 kHz and the other is 7 kHz to 100 kHz. So in theory both those ranges should be able to output a waveform of 10 kHz but when trying this both give different frequencies.

I would put this down to a fault but it has happened on both units so am I doing something wrong?

Thanks

Andy

I'm not too bothered I have two new edulab ones that function well.
 
My guess is that it's just that the calibration is a bit off. We tend to put an oscilloscope on ours if we do anything quantitative involving the frequency (even with our newer digital models - some of those are way out).
 
Yes our older ones have long drifted away. As with Chris, we use a calibrated oscilloscope to check them and find what their frequencies are at the time we use them...
 
If they are old, almost certainly the Capacitors have dried out a bit and gone out of tolerance. If you can get into it, there is an electronics techie trick. Get some freezer spray, connect up a loudspeaker and cool down some of the capacitors. Replace the ones that alter the output. Even works on transistors and some IC's.
 
If they are old, almost certainly the Capacitors have dried out a bit and gone out of tolerance. If you can get into it, there is an electronics techie trick. Get some freezer spray, connect up a loudspeaker and cool down some of the capacitors. Replace the ones that alter the output. Even works on transistors and some IC's.
Could this account for very quiet output? I had a look inside but nothing was obvious and I wasn’t sure how to proceed. Debating whether it’s worth keeping in the techlab pile or whether it’s BER.
 
Could this account for very quiet output? I had a look inside but nothing was obvious and I wasn’t sure how to proceed. Debating whether it’s worth keeping in the techlab pile or whether it’s BER.
Probably not the output level, more the calibrated frequency. I can't think of a mechanism that would effect the volume, even a dirty pot would just crackle a bit. I would expect a work, not work problem if it was just age related. Some of ours have two outputs, high impedance for an O'scope and a low impedance for a speaker, that would effect the output level. Other than that I'm stumped.
 
Probably not the output level, more the calibrated frequency. I can't think of a mechanism that would effect the volume, even a dirty pot would just crackle a bit. I would expect a work, not work problem if it was just age related. Some of ours have two outputs, high impedance for an O'scope and a low impedance for a speaker, that would effect the output level. Other than that I'm stumped.
Ah well it can wait until we’ve got some more stuff to keep it company and I’ll see what techlab say.
 
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