triode

Actually this is good practical advice, I was planning to use fiberglass raisin and Plaster of Paris mixed. But the way I solve it (at least it is working for a more than a month now and it is not burning) is by replacing the tuning screws with brass crews and turn them on the lathe removing threads making ends cone-shaped approximately 30 degrees and 3mm cone, thinking that cone-shape is better than uneven threads area and creates some air gap between Teflon and screws. I also took insert from receiving side and switch them to transmitting side and put DIY inserts made from 3d printer filament guide into receiving side. Then I tune duplexer with VNA(SV4401A) as best as I could and fine tune it by the sound(listening on the radio) decreasing attenuation of RF signal (coming from tinySA) for better rejection as I tune. Again is this a good solution, probably not but it works for now. Next time around I will cut the tuning tubes and solder the wider copper or brass tubes on top of it, then will turn Teflon inserts on the lathe for wider diameter of new tubes, also silver plate tubes and screws after tuning them on the lathe. Thank you so much for taking your time to respond.

This would not be a tunning, sellers tuned two, another was send to tuning service, later rest of duplexers I tunned myself. Some served longer than others but then burned inside. I am surprised there is no information on this issue. I am using KG-1000G plus on transmitter side, maybe radios is the problem. Thank you for responding.

Posting the image of the duplexer for gortex2.

Again doing the same thing 3 times or more and expecting different results does not really apply here. When Teflon burns and you don't know it yet, you hear all kinds sounds audio is getting bad while transmitting I had to look at controller making sure there is no problems with circuitry I have made. Power supplies, fan filters, antennas and only then started looking at the duplexers because it does not always immediately going bad it retains tuning for a while when testing with VNA even with burned Teflon. So Teflon is the source of experience (lol) Yes I have noticed reducing power in half like to 20 watts does helping the leak to receiver side with little impact on transmitting distance. But again this is work around, if I agree with it then I will stop looking for solution.

According my understanding everything is grounded including myself (lol). The only doubts I have about jumper cables I use 1/2 weave length and approaching 50ohms at both ends for transmitter and receiver. I am using rg174 and 25ft cable to LMR400 cable to antenna. Yes is analog. Again inserts are getting burned randomly there is no specific duration. One of the duplexers from XLT Communications burned immediately and it is most expensive one I have.

Yes and No, I could buy one good duplexer for price for 3 but I purchased them over period time and as I worked through problems I gain experience in building repeaters, tuning antennas, duplexers, troubleshooting, writing code for controllers, making interfaces between radios and cliché statements about "banging head in to the wall" does not really answering my question, but thank you for your input. Money can solve many problems but, in my opinion, it is most primitive, boring solution, and at the end with no satisfaction/reward but emptiness, please if this is all you can say "spend more money" do not use your valuable time writing it. Nothing is permanent, maybe(most likely) I would end up spending more money but hobby for me is not having working solutions but the process itself of making it work. Also I am not looking for opinion please post your real solution if you have it, If not maybe I will post mine if I solve it. I am sure someone will benefit from making work so called cheap duplexer. Thank You all for your time and advice.

Yes, I took all of them a part and move inserts from HIGH side to LOW side and make DIY inserts for HIGH side from 3D printer Teflon filament guide cable.

Getting something like 633-6A-2N maybe a solution but I really want to fix those duplexers I already burn because they worked well when they did.

SGQ-450A-D 50watt, duty cycle I am not sure but I am assuming duplexer should run continuously. I don't recall seeing duty cycle on the duplexer parameters list.

Hello everyone, Please advice. I am on my third duplexer now I keep on burning Teflon inserts on transmitter side. It works for a week or so then gradually I am hearing popping sounds and distance drops. Checking duplexer with SV4401A and it is completely out of tune both HIGH and LOW sides effected. I am using KG-1000G plus and it outputs approximately 38-45(fluctuating) watt. My question is. What do I do besides reducing transmitter power and does anyone know where I can purchase the insert replacements or maybe there is a DIY solution for this. BTW. I tried to replace it with Teflon tube from 3D printer filament line. After tuning it lasted about 3 minutes with 50ohm load (burned). again, this happens to 3 duplexers. Thank You.

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