Topband: preamp transistor

G B microsys at alltel.net
Thu Nov 15 09:49:25 EST 2007


Hello,

I could not find any 40673 dual gate mosfet on digikey's site.
So, did some hunting.

Turns out there is a very cheap, new dual gate called a BF981, 30v
40ma.  Has anyone tried this smt part?  It says it is used in VHF
radio/tv tuners and has a NF of 1.2db.

I am going to try one in that KD9SV variable gain preamp.  I will let you
know how it works.

I found the band extremely noisy last night, and the signals weak down
south.
I called two eu stations, and one heard me slightly and got part of my call.

The reason I tried, is that I finished the mod on the SB-220 yesterday, and
am
getting 525W CW out of it.  Not enough, but I cannot figure out why so low,
and
the tune control is at max.  With a single tube running, it puts out 750W CW
on
80M.

73's

Glen K4KV




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