[FRC] Palomar preamp - improving

N2TK n2tk@arrl.net
Mon, 25 Feb 2002 20:05:38 -0500


I have been trying to improve the Palomar P-310X preamp. My reference is an
Ameco PCL-P nuvistor preamp. Before the mods, the Ameco was the hands down
winner on most bands. After the mods the Palomar is better than the Ameco on
160 and 30m. It is a toss-up on all the other bands except 10 and 12m. With
the Ameco, the signals seem to pop out of the noise on 10 and 12m, whereas
with the Palomar the noise level increases more than the signal, so the
signal disappears.

Here is what I did, courtesy of K3CT;
- Replace FET 40673 with SK3050
- Remove C2 from pin4 to pin2 of FET
- Remove D1, D2, D3 and D4
- Added a ferrite bead to pin 2 of the FET (not sure what value on bead).

Should I use a different FET?
Should I try a different ferrite bead on the FET?
Any suggestions on how to improve this are appreciated.

This preamp is in my receive line, so even though it can be used on the
transmit line, it is only used as a receive preamp.

73,
Tony
N2TK