900 MHz Duplexer?

Jonathan KC8RYW · Post by **Jonathan KC8RYW** » Mon Jul 29, 2002 9:11 pm

Anyone know of any good, cheap 900 MHz duplexers?

How much would they run?

What are the specs of them?

Thanks

N9LLO · Post by **N9LLO** » Tue Jul 30, 2002 4:50 am

Back in 93 whan I built my 900 system I had Cellwave make me a
small mobile type duplexer. 6 cavity 12meg split 50watt rating.
I think at the time it cost me about $225. I recently sold it here for about $100. I have since taken some Decible 800 cans and built up a harness to use them on 900-12split and built the repeater with an old EXEC II 800 with an EXEC II 460 exciter board mounted in the bottom to drive the LO with the second harmonic. This mod was detailed in 73 magazine several years ago. However I have yet to put it on the air because I really only had two guys using the old system. I may get it going again someday when they put out a ham rig to cover the band.

Chris

Jonathan KC8RYW · Post by **Jonathan KC8RYW** » Tue Jul 30, 2002 8:44 am

N9LLO wrote:However I have yet to put it on the air because I really only had two guys using the old system. I may get it going again someday when they put out a ham rig to cover the band.

Isn't that the truth.

I wonder if the popular commercial ham radio makers will ever realize that 33 cm exists. If there is a ham rig made for 33cm, I have yet to see it. There are no 33cm repeaters coordinated in Michigan. Starting up one would be a breeze... no coordination headaches.

A little higher up in frequency, there is a small amount of activity on 23 cm, judging by the fact that there is a 23cm mobile (Kenwood TM-742AD, with the 1200 MHz option) and there are a few (nine) coordinated 23cm repeaters here in Michigan. I've seen some multi-band antennas (base, mobile and portable) supporting 23 cm.

It would probably be easier if someone mass-produced a 900MHz transverter.

kb8zqz · Post by **kb8zqz** » Sun Sep 01, 2002 5:27 am

There are several groups in Michigan working on 900 repeaters. The Grand Rapids group has just about got theirs on the air, I think. The Michigan State U. club is getting close. These will be roughly 25 MHz split. Someone proposed to the Michigan coordinating body that they adopt the SERA bandplan for 902, in place of the ARRL one, before any repeaters are coordinated.

Repeaters are built out of pairs of Maxtracs, one 900, one 800. Folks building interest in this have been gathering Maxtrac, Spectra and GTX mobiles, and GTX handhelds, to provide interested users with rigs.

At one point not too long ago, RELM was selling off excess inventory, and the list included some 902 duplexers. If I read my analyzer right, these extend just far enough into the 902 band to be used without retuning for at least some of the 25 MHz split pairs.

It seems that mfgs don't pay much attention to 902 since it's not widely allocated outside of the US.