Bp/Br Duplexer Upgrade

As many of you know, my 442.175 repeater has been running w/ a mobile style duplexer for little over a year.  I had no issues w/ its performance per se.  Although, in order to provide the best quality of service, a band pass-band reject cavity duplexer would be the best way to go from an investment standpoint.  At some point in time, I might get a 100W amp for my repeater, and therefore, a duplexer that’s able to address the input power of this level would be good.  Additionally, from isolation/separation standpoint a decent db tolerance would be a good one to keep a close eye on as I made this investment.

Three weeks or so ago, I had bumped into a duplexer that fit this bill., not the cheapest from cost standpoint that I was hoping to find.  However, the seller was open to negotiating and we closed the deal.  The duplexer specs are below, it’s made by Sinclair, a 4 cavity, Bp/Br/75db isolation/350W max input 2U dimension unit.  Well taken care of and very nicely made.

I had the seller ship out the duplexer to a good friend of ours, W0XL – Joe Zwirn, a veteran in this HAM radio space, a craftsman who knows all about duplexers and tuning;  Joe had helped me w/ tuning my mobile duplexer, and many people were surprised to see that a mobile duplexer would be that nicely tuned to performance.

Thanks to Joe, the new duplexer is now tuned up to 442.175/+5 coordination and she’s successfully now replaced my mobile duplexer.

Below here, you will find some pictures, specs and a short YouTube video of this effort.

I will be doing some RF testing for the next few weeks and hope that this indeed justifies to be a good investment.

Thanks, 73





YouTube Video: