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Receiving S-Band with MMDS ant!


	Today I clearly received UO-11 S-band beacon with a modified
California-Amplifier MMDS antenna alone (no preamp)!. It was an 18deg. max
elevation pass and I heard the beacon for 2-3 minutes. The doppler shift is
terrific, I could not take my hand from the VFO knob to keep a constant
audio tone! 
	The most interesting part is that I used what Cal.Amp. calls LNBY, a 20+
disc array with an integrated downconverter at its back, with no parabolic
reflector at all!!. The model is 130194, its technical details are on
Cal.Amp. web page, it is the lowest NF and highest Gain model. Another
important fact is that this model does not include a PCS/WCS/Radar Filter,
which may wipe out 2400MHz signals.
	Of course the converters' LO synthesizer reference crystal had to be
changed and also I had to bypass some output filtering circuits, but this
was straightforward. I ordered an 8.772222MHz crystal from Nebraska surplus
(US$4) and replaced the original one. I soldered a short piece of wire to
bypass some printed-circuit inductors and SMD capacitors that are between a
device marked "RF 6X" and the ouput F connector and closed it back.
	I checked that noise floor increased when I supplied DC thru the coax and
mounted the thing on the cross-boom. I placed a 50ohm attenuator (or 20m of
RG-58) between it and my IC-821H and that's all.
	I followed the converted signal from 155.776MHz to 155.752MHz along the
pass and took notes of the freq indicated by FODTrack and my rigs' display.
When FODTrack said 2401.503MHz I had tuned the rig on 155.764MHz.
	It is the cheapest and simplest S-Band receiving approach I read/heard
about, I paid US$190 for the LNBY at a local (Uruguay) TV-antennae store
and around US$4 for the surplus crystal.

	If anybody needs more details about this system do not hesitate to e-mail!

	73 de CX6DD