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CL: Lot of 5 Tek 453's

 

It's been a while and I didn't take notes but I remember that I could see that the phase info (U1902 PFC, pin 23) was dead (steady state). Of course, I first looked at TC1 (pin 1) and VCO (pin 26) and found both alive and well, so the X-tal oscillator and U1904D (level shifter) couldn't be the problem. Partly just for confirmation of my conclusion, I decided to just cut pin 23 (PFC) and put in one gate of a socketed 'LS86 between pins 1, 26 (inputs), and 23 (output). Works a treat! As said, a bit rough but accurate and stable. I think that i didn't even put in a pull-up resistor at pin 23, which strictly speaking shouldn't be necessary but may improve shape and level. Of course, a bit of HF jitter does no harm in this application and is actually inserted through pin 22 (Noise).

Raymond

 

And again, it lands here! It should be in the "2247A 2252 Timer Counter Reference" thread!

Raymond

 

Sorry, I give up. No use fighting against a Yahoo.

Raymond