Re: PG502 freq too low


The specifications say <= 4 nanoseconds. 5 nanoseconds is 200 MHz so
how much faster should it go?

The circuit built around U150A is the fast period generator. I would
check the values of the resistors around it and swap U150 for U180 or
U260 to see if that changes anything.

The ECL logic runs on +5 volts so I would take a careful look at the
+5 volt supply. Check for level and noise when operating. Check that
bulk decoupling capacitor C650 is good. If C650 is bad, then the +5
volt regulator might behave oddly allowing the +5 volt supply to

On 30 May 2016 12:46:26 -0700, you wrote:


I just got a PG502 pulse generator. After I fixed a bad solder joint on one of the pots, everything seems to be good, , except for the 250MHz setting. It only goes up to 200MHz. All other ranges are spot on, i checked all steps in the SM for adjustments.
According to the service manual, there is no internal adjustment for this frequency range, it's implemented as a separate multivibrator.
Any advice on where I should be looking?



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