I was looking at cheap HT's last night on eBay and I found several vendors
selling duplexers for repeater use. They sell for about $60 each.

They are 6 cavity (three transmit, three receive) and the closest they can
go on VHF is 3.5mHz.

Doing a web search I find they are not very good (what did you expect?)
but with a good front end they will work ok.

My problem is not only one of money (don't tell me to not waste my money
and buy a good, one, I can't afford it), but my 2m band is only 144-146
mHz, and the repeater portion is really just 145-146. I'm also limited
to 20w output.

So my question is anyone familar with them? Is it possible to take one
and convert it to a 6 cavity input filter? For example, I could put the
input on one side my yard and the output on the other, about 30 feet apart.

For example, if the input of the repeater was 145.600, could I have them
both tuned to 145.600 and connect the input of the receiver to one
set of cavities, the antenna to the other and leave the antenna connection
untouched, effectively placing them in series?

Thanks in advance,

Geoff.






--
Geoffrey S. Mendelson N3OWJ/4X1GM
Making your enemy reliant on software you support is the best revenge.