Duplexer Tuning

[WRTA578]

First time tuning one on my own so asking the Experts in here is this OK? I know I am not using a 15K piece of equipment to tune it but is this OK as is or should i take it to a radio shop and see if we can deepen the notches more? its an RFS flatpack

 

 

[tweiss3]

The level  of isolation is pretty good. It looks on the top side that you could  align the the cavities a bit better, they should show only 1 combined dip. Similarly for the bottom, it appears only 1 of the cavities needs aligned with the other.

[WRTA578]

6 hours ago, tweiss3 said:

The level  of isolation is pretty good. It looks on the top side that you could  align the the cavities a bit better, they should show only 1 combined dip. Similarly for the bottom, it appears only 1 of the cavities needs aligned with the other.

I am using a SAA-2N NANOVNA with the Nano VNA app for PC the notches vary from 85ish to 103ish i have tried to get them tighter but i believe my resolution just isnt good enough was just trying to save $200 for tuning from the shop I do like that my S21 was able to get to -0.96 so 1DB loss i assume for transmit and receive which is way better than my Chinese flat pack that is -2.3DB just wondering if you think it will be an improvement over my current installed Chinese Duplexer 

[tweiss3]

Yes, I tuned my duplexer with the PC app, and turned the resolution up as high as it goes (refresh rate takes a hit, but its not an issue). I then took it to a friend that had the shop equipment, and it left his bench untouched.

You are likely looking at very small changes to be made. You can move the screw less than half a turn until it pops out one side, then move it till it pops out the other, and end up in the middle of those two locations. It may be as little as 1/8 turn or less. You do, however, get the concept and did a decent job for a first go around. Will it work as tuned? Yep. 

[WRTA578]

30 minutes ago, tweiss3 said:

Yes, I tuned my duplexer with the PC app, and turned the resolution up as high as it goes (refresh rate takes a hit, but its not an issue). I then took it to a friend that had the shop equipment, and it left his bench untouched.

You are likely looking at very small changes to be made. You can move the screw less than half a turn until it pops out one side, then move it till it pops out the other, and end up in the middle of those two locations. It may be as little as 1/8 turn or less. You do, however, get the concept and did a decent job for a first go around. Will it work as tuned? Yep. 

Thank You for your input....  Tuning a duplexer was something i steered away from for my whole life but thx to Cheap NANOVNA's and You Tube i was able to tackle it...  I have 7 repeaters i bought at Gov Auction TKR-851's and all have duplexers I have tuned 2 for 462.6 and 2 for 462.7 so if a failure its a fast cable swap and in goes a whole new repeater....  still waiting on linking hardware so i can link my 2 running repeaters to make my group happy....   now if i could understand how to have 2 repeaters with duplexers on 1 antenna then i could offer to separate systems to my users

[WRQL370]

You can use two repeaters , one duplexer with a combiner, but you have to keep the frequencies close together so everything falls within the pass/reject band of the duplexers. The duplexer tuning will have to be slightly staggered so you take a bit of performance hit, but if you don't have tower space for a dedicated RCV antenna and a rcv multicoupler with a pre-selector,  it could work.

The down side is the cost of a combiner. Even two channel hybrid combiners are salty used.
 

[gortex2]

Normally in multiple repeaters you use a combiner on TX and a multicoupler on RX. The issue is the GMRS repeaters are pretty close and it takes a good combiner to make it work right. I have our SAR repeater (453.xxx) and a GMRS repeater in my combiner with 3 repeaters using a receive multicoupler. The 3rd SAR repeater uses its own TX antenna. 

[wrmd298]

Be sure to terminate the open port with a 50 ohm load.  This will get rid of those jagged notches and make the notch defined and smooth.