Variactor diode for receive loop


Does variactor variable capaciance diode has high Q factor that is comparable to air cap?   

Can it be used for receive loop?  

Prelimary loop calculator shows signal at says -30 dBm will induce tens of mV and NOT significantly affecting the cap value.

Immo, DL5KB

hi Simon,
main issue will be to find a Varicap which gives up to 50pF. I did a little calculation: Loop consisting of thin wire, i.e. 1.5mm diameter and loop of 60cm with 3 close windings will have abt. 15µH. For tuning it to 7MHz you need 35pF.
The blocking inductivity should be abt. 10 times the loop inductivity. 

I don't believe, that there will be any issues, except if you transmit on similar frequences nearby. 

So, do a try and let us know your success or issues.

Gary W9TD

DC blocking capacitor required or else loop shorts out the varactor bias.

Immo, DL5KB

at the first drawing I missed the blocking C. Thanks to Gary!