[Elecraft] Antenna sharing question

[Mike Scott]

>I have 6m on the K3, 2m on my XV144 and 4m to come.  I use only 1 
antenna with these, a Create log periodic.  Is there a simple way to 
connect all three to the aerial without using a switch?

Ian,

The standard (no-switch) approach to connect a single broadband antenna to
three separate transceiver ports that operate on different bands is to use a
triplexer. A triplexer is something like three separate band-pass filters
that take energy in separate bands and routes the energy to three separate
physical ports.

You can find triplexer products if you Google the term. Your issue is quite
unique however with the 4m band. There may be a European triplexer source
but since this band isn't available here the US manufacturers are unlikely
to have a suitable product. 

You might be able to build your own triplexer but you may really be better
off with relays automatically driven from a combination of K3 band decode
and the 4M rig PTT circuit. I am assuming the K3 drives 6M and the XV144 on
2M and the 4M rig is separate transceiver. You might find a commercial
diplexer that handles the 2M and 6M bands leaving you with a hardware switch
or relay for 4M operation.

Triplexers need to be built with substantial port-to-port isolation, this
might prove difficult in a homebrewed unit, don't know for sure as I have
never built one. If you live in an area with risk of lightning strikes then
you have something else to add to the homebrew worries.

eHam reviews a long list of antenna switches at:
http://www.eham.net/reviews/products/2

Good luck.

Mike Scott
AE6WA Tarzana, CA
K3/100 SN508