Hi folks,
So, a follow-up to my previous message. All this discussion about EME got me
thinking... We're always taught to put your preamp as close to the feed point
as possible, but as with everything, there are tradeoffs. Where should the
Preamp be mounted?
Choices:
1 - on the antenna boom, at the feed point (or attached to the CP relay)
2 - on the rotor cross arm
3 - below the rotor, where the flex transitions to the main feed
I'm thinking that #1 is a problem. Yes, it's the shortest run, but you've got
the weight of the preamp
at the far end of the antenna, unbalancing things. Depending on the antenna,
it might be right in the middle of a bunch of elements, so putting a metal box
there might upset the antenna's performance or impedance. It's would also be
subjected
to the strong RF fields of the antenna during transmit.
#2 is probably the best; fairly short coax run on the antenna side, and
somewhat outside of the RF field.
#3 (what I have) is most convenient, and has one less set of connectors to go
bad, and one less wire to snake around the rotor. Weather proofing is easier
when the object being proofed can't move, and mounting the preamp on the tower,
for me at least, is a lot easier. And, it's not THAT much more coax to the
antenna.
Thoughts?
Greg KO6TH
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