Nathan wrote:
I have two antennas that I would like to share between
four receivers. I have looked on serveral sites and I
don't see anything that will allow me to do this. The
Ideal situation would allow me to select between the
antennas and receivers and not have to disconnect /
connect antennas. Does anyone know where I might find
such a device. My ability to build a device is very
limited .

I think you will find an economical solution by using A/V switches provided
you can connect to your antenna feedlines using co-ax . The video path of
these switches will certainly be good enough from LW to SW; anyway, a little
leakage to the unselected receivers is harmless. You might even be able to
use the audio path to route the audio from the selected receiver to an amp
or speaker so that pushing one button connects one of the four radios to
both the antenna and the speaker.

An example is Radio Shack Catalog #: 15-1976 for US$29.99. Buy two, 1 for
each antenna. This model uses RCA phono connectors for both video and audio.
You can get high quality co-ax cable with RCA plugs but you can get away
with cheaper audio quality cables over these short lengths if you're not
fighting a lot of interference from sources close to the equipment. Connect
the Video Output of one switcher to the antenna; do the same with the other
switcher and antenna. Yes, the Output - use them in reverse - they are
passive switchers (as far as I can tell from the on-line description) and
don't care which direction electrons flow. At each receiver, adapt the
antenna input to a Y-adapter so that each radio connects to one of the Video
Inputs of each switcher. The Y-adapter is readily available as an audio
accessory or you can use T-adapters. Yes, with this setup, both antennas can
be connected to the same radio, but, with different radios selected, the
short stub to th other switcher in parallel with the active feedline will be
of no consequence at SW and lower frequencies. I don't know what the
switcher does to unused ports - if it leaves them open, no problem, if it
shorts them then it's not going to work. As for the audio routing, connect
your speaker or amp to the switcher's Left Audio Output and the radio
Speaker or Line out to the Left Audio Input that corresponds with the Video
Input connected to its antenna jack. It's probably safer to use Line Outs
and an amp.

The Shack also has a 3-position "high isolation" A/B/C switch Catalog #:
15-1218 for $11.99 using F connectors. It looks to be an RF device even
though it's described as 'video' and does not include audio routing. Too bad
it's not 4-position. You would need 2 of these plus 2 more of the 2-position
switcher Catalog #: 15-1217 at $8.99 ea to do your 2x4 routing. Or you could
use one on each radio, Y-ing each antenna to an input on each switcher
leaving one input on each unconnected or terminated in 75 ohms. That way,
you could connect any number of radios to either antenna - the interaction
between 2-4 radios on the same antenna might be acceptable if it lets you
monitor 4 desired signals simultaneously. My DX-394's (3 of them) have both
low and high impedance antenna inputs; using the LO-Z on one in parallel
with the HI-Z on the others to minimise loading is not awful. However,
paralleling one with a Drake R-4B is much worse - the Drake's pre-selector
really sucks down signals outside of its selected range.

Another approach that reduces the switching to a 2x1 for each radio is to
use a 1-to-4 CATV splitter from each antenna and hope that the losses will
be tolerable.

Good luck!

Tom