On Thu, 19 Jul 2012 13:49:48 +0100, "Richard Ferryman"
wrote:

I want to run two or even three QRP (200mW) HF beacons to one antenna. Is
it possible to build a duplexer to combine 8M and 40M or 30M and 40M or 30M
and 20M. Does anyone have a pointer to a web site where I might get some
tips?

If you check the web sites for the various beacon networks, NONE of
them transmit on more than one frequency at a time. The transmissions
on each band are done in rotation. You do NOT need a duplexer,
diplexer, perplexer, or antenna tuner.

The danger in transmitting simultaneously on multiple bands at the
same time is intermod mixing generated in the final stages of your
transmitter. Ask Field Day operators for how that works. For a
beacon, all you need is a multiband antenna of some sorts and a uP
controller to change bands and frequencies according to a set pattern.

http://www.ncdxf.org/beacon/photos/index.html
Contact anyone involved in the network for details and horror stories.
http://www.ncdxf.org/beacon/beaconcontact.html

--
Jeff Liebermann
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558