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Old 4th Dec 2017, 1:59 pm   #2
KeithsTV
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Join Date: Aug 2007
Location: South Bradford, West Yorkshire, UK.
Posts: 2,571
Default Re: Systron-Donner 1702 sig gen.

I acquired a Farnell sig gen about 20 years ago with a fault. It's only 10MHz to 520MHz and uses, from memory, 8 separate oscillators each of which is selected depending on the frequency set on the thumbwheels. It showed no sign of locking which was, after some signal tracing down to the 100Hz reference signal for the PLLs being shorted to ground by a faulty feed through cap.

As it's not locking on any range I'd suggest tracing the master oscillator signal through the various divider stages to make sure the reference to the PLL phase detector, which may well be 100Hz or 50Hz, is present. Then look for any output from the divider chain from the VCOs. There may well be more than one phase detector because of the wide frequency range.

I know what you mean about the missing extension board!! You may have to solder wires to the various points you need to monitor before making measurements. But for $15 you can't complain.

Keith
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