Duplexer/Cavity tuning with my Rigol SA

March 1, 2022 - Both sets together.  Yellow RX (3 cans right) and TX (2 cans left).

February 9, 2022 - Added the new BpBr cavity to the bandpass set - result below.

February 8, 2022 - new BpBr cavity purchased off eBay - I tuned for RX side.  Currently set to Pass 448.200 RX and reject 443.200 TX.

February 7, 2022 - combined notch filter/mobile duplexer on the SA.

February 6, 2022 - tuning the notch filter/mobile duplexer that goes with my 442.4875+ DMR Repeater.  Yellow is the Low/TX 442.4875 and purple is High/RX 447.4875.

February 1, 2022 - retuned the TXRX cans for the RX side - pass 448.200.  First picture both cans - next two are pictures of each can.  I have ordered a BpBr filter to go with these on the RX side - I'll notch out the TX 443.200 on it and pass RX 448.200.

January 30, 2022 - tuned up a 70cm notch filter and combined it with my bandpass filter (retuned) for the TX side - pass 443.200 and reject 448.200.

January 22, 2022 - tuning a 900MHz bandpass filter I bought off of eBay.  I am not using the directional coupler here.

January 22, 2022 - this is the the UHF set below - I found a cable to connect the set that seems to be about the right length.

January 18, 2022 - below are two pictures of the UHF set Fred (N4CLA) gave me.  I am testing with the directional coupler.  The non-symmetrical area on the right is because the connection between the two cans is not the correct length for the frequency (448.300MHz) I currently have them tuned for.  I will be doing research on how to determine the correct length of that connecting cable next.

 

January 11, 2022 - below two pictures I tested the VHF set testing with the directional coupler.

January 10, 2022 - I was given a set of VHF and a set of UHF band-pass cavities by Fred (N4CLA) - below I tested the VHF set without the directional coupler.

Yellow is one can and purple is with both cans.

Here (below) yellow is both and purple is one can.  At a -600kHz offset marker 1 is only about 15db from the main 145.17 frequency (marker 2) - this leads me to believe these are commercial cans for a much larger spacing between TX and RX.

November 24, 2021 - Using a directional coupler to tune a band-pass cavity with my Rigol DSA-815TG (with a Tracking Generator).  Using this method you see reflected power which helps zero in on the setting.

Put a 10dB attenuator at the TG output to protect the SA from excessive reflected power.

The TG output goes into the "OUT" and the "CPL" connects to the SA input.  The "IN" goes to a port on the cavity and you terminate with 50 ohms the other port.