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Need recommendations on 435 yagi feed



What I'd like to achieve is switching between left-hand and right-hand
circular polarization with an antenna I have on hand for the 435 MHz uplink.
I've read everything I can find, including the latest Satellite Handbook,
which illustrates some methods in Figure 10:11.  I also have on hand a very
low loss relay with N connectors.  What I need is this: based on your vast
experience with these things, what's the most cost effective way to
accomplish the switching while keeping losses under control.   I forgot to
mention: the antenna, of unknown manufacturer, has two crossed yagis of 10
elements each on a 57 inch boom.  The feed points are gamma matches, with an
SO-239 connector as part of the gamma match (can't easily be changed to N
connector).  The two sets of elements are offset by only 1 inch along the
boom - not 1/4 wavelength or 90 degrees as with some of the newer antennas.
Now the details:

Technique "A" in figure 10.11 involves using a relay to switch a 90 degree
phasing line of RG-133/U coax in series with one or the other antennas.  One
of the satellite books mentioned that this coax is "hard to get".  I've not
been able to locate a distributor at all.  I suppose one option would be to
use RG-62 which is 93 ohms instead of the 95 ohms of the RG-133.  Of course,
that brings with it some connector fastening problems.

This technique involves running a 1/4 wavelength of 75 ohm coax from each
driven element (which I'll assume are adjusted for 50 ohms) to a pole of the
relay and the 1/4 wavelength of RG-133 is also connected to those same relay
points.  The feedline is then connected to the operating contact of the SPDT
relay.  Operating the relay causes one yagi to be fed directly, and the
other to be fed via the 1/4 wavelength of RG-133.  A rather simple
configuration, but the only Tee connectors for N connections I found were
$55 each and two would be needed.

If I were to use standard UHF Tee connectors (accommodating PL-259s) and the
necessary PL-259s, that would put three PL-259s in the circuit to one yagi
and two to the other.  Will that be an unreasonable amount of loss?  Is it
worth the trouble to use RG-11 for the 75 Ohm 1/4 wave matching sections, or
is RG-59 acceptable?  Along that line, perhaps it would make more sense to
use F connectors on RG-6 and RG-62 instead of the larger cables?  Would the
F connectors withstand 20 watts?  100 watts?  I assume that using one of the
SO-239 to male N connector adapters would also introduce a loss at these
frequencies.

So, give all this, how would you accomplish the objective?  Thanks for any
info you can provide.


K8AC
Floyd Sense - Angier, NC

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