wrote:

I think part of the reason for little information or enthusiam is the
diodes tendancy for IMD on strong signals. This increases the
complexity of the circuit. You might check with the ARRL and see if any
information is available from past QEX articles. I am researching the
same thing for a HF preselector. I am going to experiment with solid
state relays. Just a suggestion. Try the Vishay site
as(http://www.vishay.com/solid-state-relays/). I have found little info
on varactor tuned pre-selectors

Are those things specified for RF? I wouldn't touch them with a 10-foot
pole if they aren't. If you're planning on tuning by switching elements
in and out have you considered PIN diodes? If you have them either all
the way on or all the way off they should be less susceptable to IMD
than varactors. Furthermore, I understand that if you're cheap you can
use the old 1N400x series of power diodes at HF (I haven't tried this,
though).

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Tim Wescott
Wescott Design Services
http://www.wescottdesign.com