Batboard

Would something like this be feasbile/workable?

Sinclair C3037 or 2037 expandable multicoupler which consists of a set of 1 reject and 3 pass cavities with a feedthrough harness for each tx or rx frequency

So normally you would have a set of 2 sets of 4 cavities for each repeater, and at the end of the multicoupling chain, you terminate the last feedthrough with a 50 ohm load

Instead of putting a load at the end of the chain, could you put a duplexer?

Thoughts?

Cx037 cans are great, but a little on the pricey side

I suppose. As long as the freqs of interest in the duplexer are not within 500k of the pass or reject in the Sinclair multicoupler. You would have to test it, and I would do it on the tx chain to let the least amount of smoke out.

This would only work if the duplexer was a bandpass bandpass design and if all the multicoupled frequencies lay in the passband of the relevant duplexer branch. In practice most everyone uses two antennas because most duplexers are designed with either notches or an asymmetric bandpass which would not favour all your frequencies equally AND because, as you say, cans are expensive.

Oh. You think he wants to use one antenna through a duplexer rather than a tx and rx antenna. I didn't read that at first, but see it now. You're right. He has to have a pass duplexer, and all the freqs have to fall within the correct pass band of each side. Might be difficult since the Sinclair requires 500k separation between combined freqs. Might work.

PS - is it just me, or do anyone else think receivers when the word multicoupler is used? I combine transmitters. I multicouple receivers. Sinclair seems to be using the word for both.

I agree with you Bill - multicouple receivers and combine transmitters is the industry norm, despite the exceptions. But like the duplexer (tx/rx filters) vs diplexer (two band filter) arguments there are various viewpoints...

We have extensivly used C2037's and C3037's (and the rezloc versions C2034 and C3034's) and have seen excatly what you're describing. It's not ideal. The terminaiting load is there to disipate all pass-through RF. With a duplexer, that pass-through RF gets reflected back up the string.

I agree with Astro Spectra, if you do it, it should be a band-pass duplexer. I have worked on one system with a quasi-bandpass duplexer at the end of the string (Q series) and there was issues with RX Desense on the RX that was on the duplexer.

Bill_G wrote:PS - is it just me, or do anyone else think receivers when the word multicoupler is used? I combine transmitters. I multicouple receivers. Sinclair seems to be using the word for both.

Sinclair has always refered to their C series as multicouplers. Other than these products, I too think of receivers for multicouplers and combiners for transmitters.