To continue my series of destroying perfectly good VHF duplexers to modify to the 220Mhz band, I have started modifying a Sinclair Q2222E.
http://www.sinclairtechnologies.com/catalog/product.aspx?id=74 The Q2222E is a weird beast, in that it is about the size of a UHF Q3220E duplexer, but is designed for VHF with a folded cavity design. So modified it is a nice compact duplexer that will work well in the 220Mhz band. I took what lessons I learned from modifying a Q2220E VHF duplexer to 220Mhz and applied them to this beast. If you had not seen that project, please go to: http://www.irlp.net/duplexer/ The modifications to the harness are the same as the Q2220E, and the modifications to the internals of the duplexer are even easier. What resulted was a perfectly usable 220Mhz duplexer, with about 80db isolation on TX and RX, with about 1.6db of insertion loss on TX and RX at 1.6Mhz split. >From what I have seen, in the used market Q2222E duplexers are almost given >away, because they have poor specs with a 600khz split. This duplexer works very well with a converted 220 MASTR-II using a PLL exciter and 40W Mitsubishi brick amplifier. I have posted the raw pictures to a website if you want to have a look. I plan to make an addendum to the Q2220E modification site soon. http://www.irlp.net/q2222e/ Dave Cameron VE7LTD
