[AMPS] Re: 6m amp blocking caps

Tom Rauch W8JI@contesting.com
Wed, 5 Dec 2001 09:45:21 -0500

> >>
> >//   Why not?   Is the sharp dip I see on the dipmeter a pseudo-dip?
> >
> Certainly it's real. When you connect the two capacitors together at
> each end, you make a series-resonant loop. Guessing at values, two
> 1000pF caps, in series with a total of 8nH lead inductance + self
> inductance, comes out at 80MHz.
> But dipping the two capacitors on their own tells you *nothing* about
> their behavior in-circuit.

I see the same old "grid dip meter tells all" argument is going on!

Good luck Ian! 

Actually you can't tell a thing about whether it is a "good desirable 
dip" , something meaningless, or a potential problem with a grid dip 
meter. If you reconfigure the circuit in an attempt to find out what 
type of resonance you are dealing with, you almost always change 
the resonant frequency so much you can't tell where the hell the 
original resonance moved to.

There are many much better devices, like cheap common antenna 
analyzers especially when used with small diodes or other RF 
detectors. They are much more likely to tell you if the resonance is 
a potential problem.

73, Tom W8JI

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