Vasile Surducan <piclist9 <at> gmail.com> writes:

> I'm searching for a 200pF-300pF varactor diode with large capacitor

Please try a large silicon transistor (like 2N3055T etc). I used such a device
in an antenna tuner years ago. The advantage is that lightning is unlikely to
damage it ;-). It should even work for transmit mode for QRP. 2N3055 can be
biased up to about 80V so maybe it can reach your 1:10 range. The only real
disadvantages are size and the capacitance curve not being anti-quadratic. The
largest device I tested like this was a 'hockey puck' thyristor. It showed tens
of nF capacitance with 9V bias. I never used it for anything varicap-like (it
was too large and too expensive for this).

Peter P.



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