Steve, Peter, thanks for the suggestion for using other junctions as varactor,
I have used before the 1N4148 like varactor but don't have hyperabrupt
characteristics.I have also some space constrain so a SMD package will
be nice. Rich you had right, Partminer had it but I don't like to buy
discontinued parts. I thought someone has a direct replacement
suggestion.
I'm building a clean sinusoidal output VCO (1-10MHz) and want other
solutions than DDS (MAX8038 or other obsolete sinusoidal generators).

thx,
Vasile

On 5/29/07, Peter P. <plpeter2006@yahoo.com> wrote:
> 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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