Telewave TPRD-1554 Cavity Duplexer Tuning

Thanks for a very informative video. I bought a TRPD 1554 on ebay that was tuned to 158 mhz and 155 on the low side. I had to install 18ph capacitors on the high side to get back the 600 khz split for ham use (as Telewave recommended). However, the notch on both the TX and RX sides was on the higher side. Since I am not in the US, to send the duplexer back to Telewave, I ordered some RG402 cable and made my own coupling loops and was successful getting the notches where I wanted on both sides. When the duplexer was tuned using the Rigol 815TG, I was able to achieve over -75 db at about 1.2db insertion loss per side. However, knowing that reducing insertion loss too much lowers the Q, I chose to settle for 1.5db insertion loss that gave me better Q. Although the final effort seems satisfactory, I am assuming that my inter cavity cables might be cut for higher than the ham band. Can you please tell us the theory behind how to move notches from the low side to the high side and vice versa? Is it dependant on inductance if the loop? At least one other person has asked the same question and an answer will be beneficial to us hobbyists. Thanks Telewave.

Great video guys. You make fantastic products.

I have a combiner with 4 of these cavities in the 88 - 108 MHz band that I need to retune. How do I calculate the length of the cables?

What is the valu or specification of Piston tuning capacitor in TPRD-1454 ? It wikk be the great help

Hello, I'm making some duplexers (first time) I want to know if the TX and RX duplexers are the same, I mean they have both in TX and RX side an capacitor? because the RX side is opposite of the TX, how to get that reverse?

This video didn't show how to tune the cavities...the 1505 isnt the same as these cans.

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