Any loss ahead of your preamp adds directly to the noise figure of the
system so the best NF that you could ever have is 2.5dB plus a little
form the 221.
Also 20dB of gain in the preamp sounds like a sure way to produce
intermods in your radio.



Well of course it is Jeff, but in moonbounce, noise figure is the holy
grail. There weren't as many folks on 432 and moonbounce in particular
back in 1979, but I NEVER was plagued with intermod off the moon, and the
directivity of the array kept me from having any from anywhere else.

W4ZCB

Well that's the first FT221 I heard of working on 432MHz!! If you are
talking about that band rather than 144MHz then the cable loss would have
been far higher and the NF of the system much higher.

Having a preamp with a gain of 20dB right in front of the radio is just
plain silly. Pre-amp gains should be kept as low as possible. They should
have just sufficient gain so that their low noise figure defines the system
noise figure. Any excess gain is wasted and just asking for large signal
problems.

If NF was such a Holy Grail then why throw away a significant improvement by
putting the preamp after the feeder any degrading the system NF by the
feeder loss?

Jeff