Batboard

I need a VHF, 100 watt, 600 khz, pass-reject duplexer. Which is best, Comprod or Telewave? Which is best, round or square cavities?

Sinclair is my choice for reliability, particularly over temperature extremes.

Round is always "best" if "best" is performance. Better, sharper Q. If "best" is size/cost at the expense of performance, then look at square.

I've had wonderful experience with Telewave products.

I've had wonderful experience with Sinclair products.

I've never worked with ComProd stuff.

Seconding Telewave. Sinclair is overpriced and takes too long to get. Also worth looking at EMR. Comprod is OK too. Might could give a look at TXRX

I've been very pleased with EMR. They jumped through their ass to get me an isoplexer (duplexer plus dual isolator) when we had a critical fire repeater down. Didn't even charge me a rush fee. And the finished product was actually quite a bit better (less insertion loss and better rejection) than spec.

Heard good things about Comprod as well.

Honestly, I don't think you would go wrong with any of the companies mentioned herein. It comes down to price, support, and availability.

EMR is good stuff. If you are going to consider them, call them and speak with Alan Leffler. He's a great guy and will help you out! He's also a ham.

I help maintain two 2-meter repeaters running on Telewave duplexers. Easy to maintain and a cinch to retune. They do offer a ham discount, 5% iirc.

I've also worked with EMR for custom filters and, as tvsjr said, their customer service is above excellent. If you ever need a non-standard RF filter product they are the guys to go to.