I have been trying to improve the Palomar P-310X preamp. My reference is an
Ameco PCL-P nuvistor preamp. I have two Palomar's here to compare - one
modified and one stock. Before the mods, the Ameco was the hands down winner
on most bands. On 160-15 the Ameco won. On 12 and 10m it was a tossup. After
the mods the Palomar is now equal to the Ameco on 160 - 15m. 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:
- 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).
- Added a .1uf between pin 2 and ground.
Should I use a different FET?
Should I try a different ferrite bead on the FET?
Should I change the value of the .1 caps on pin 1 and pin4 to .01uf?
Should I put back C2 between pins 2 and 4?
I find I have plenty of gain with the Palomar and never have the gain pot
more than half way open.
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
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