Varicap rating
 

Is there a way to figure out what pf rating a Varicap is when there is no markings at all. These are for vhf tuning if that helps.

If you have a capacitance meter and a voltmeter, you can rig up a simple circuit to apply a measurable DC voltage to the Varicap while blocking it from the capacitance meter.

https://www.youtube.com/watch?v=D9eRJsswCUk

While A 1 uf cap equals to 1000nf what ceramic cap would be 1000nf.

not sure what you are asking...
ceramic cap @ 1000nf = 1uf code ia 105.

What would a 1nf ceramic cap behave like if it measures 358nf would it possibly still work or not.

:thumbsdn:

clearly not.

If it's really a 1nf cap (0.001uf /1000pf) testing at 358nf, that is way WAY out of tolerance by a factor of 350 times, which is a bit unbelievable, but if true, its very bad, or the test is lying.

What may be allowable 2-250nf to at least work

Is that a mistake? Do you really mean 1uf instead of 1nf? :scratch2:

jr

Will a 68 pf 1kv ceramic work in place of a 68 pf 100volt mica in an rf circuit?

Depends on the ceramic dielectric. NP0 or CG0 will probably work. Anything else probably not

This one is n750 whatever that means

n750 means a capacitance temperature coefficient of negative 750 parts per million per degree C.
This means it was deliberately designed to compensate temperature changes when used with a coil that increases inductance value by 750 parts per million per degree C.

So this cap may not work in a vhf rf circuit

What exactly are we discussing? Started out about a varicap, know talking about a ceramic capacitor.

What is the problem we're trying to solve?

My money is on world domination. :D