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Old March 14th 07, 01:02 PM posted to rec.radio.amateur.homebrew,sci.electronics.basics,sci.electronics.design
Anthony Fremont Anthony Fremont is offline
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First recorded activity by RadioBanter: Mar 2007
Posts: 34
Default VCXO frequency isn't high enough

colin wrote:

Its only a pull of ~100ppm, this should be easily pullable for most
fundamental xtals.


I'd like to get close to 500ppm if possible.

ofc if the tolerenace all add up against you you might find it hard.

I would also try reduce the 100pf caps on the sa602 too.
100pf is higher than most crystals I use would like,
50pf or 20pf or if youve got some spare trimmers ...
you can adjust the ratio too, say just reduce the one accross pin 6-7


I figured that they were voltage dividers to set the amount of feedback, but
I can certainly see how they could have an effect. Since I'm close to where
I need to be, I will try a couple of 33pF caps to see what happens.