[Moon] 3.4GHz Disappointing Results

[Dave Hallidy]

All-
I had hoped to be QRV on 3456 this weekend, or at least in SWL mode.  But it
was not to be, as my attempts to measure some Sun noise proved completely
fruitless.  The reasons were not obvious, but through several long phone
calls and discussions with Al W5LUA, we finally came up with the reason.

My dish, a commercial cable company head-end downlink dish, has a feed
structure that is actually a piece of circular waveguide, with the "feed"
being no more than a Chapparal-style scalar ring connected to the end of the
circular waveguide that supports it.  At the back of the dish are two WR-229
flanges- one providing vertical polarization signals, the other horizontal
(by virtue of their positioning on the circular guide feed support).  I
connected a flange and my LNA to one of these ports, expecting to detect
some Sun noise at the transverter only 8 feet away.  Nothing!  As it turns
out, the circular guide is exactly 2" ID, which we calculated is too small
to propagate 3400/3456 signals.  Apparently this system was designed to work
higher in the downlink spectrum, where the math says it would work.

So, I guess I'll have to wait to join you all on 9cm until after I get the
real feed support system built (which will then accommodate my real 23, 13,
9, 6, and 3cm feeds).
I hope you all have good luck working/hearing each other and I'll be there
as soon as I can.
73
Dave K2DH