TLD2502A duplexer

[arlojanis]

I have a TLD2502A duplexer. 148 to 174 mhz range. 1.5 min spacing. No max spacing listed. I am following instructions and trying to align for 7.63 mhz split. Transmitt power input is 60 watts and output is 15 watts. Any tips to try for less loss?

[Bill_G]

Got pretty pictures cuz my Google Fu is failing a search for TLD2502.

[arlojanis]

This is one of two in the MSF5000 manual. The other one is a 3.5 mhz min. spacing. It is 4 cavities with loops and trimmer caps.

[Bill_G]

mkay. There tends to be a high side and a low side. Have you tried tuning from both sides?

PS - are you sweeping, or tuning for max power?

[arlojanis]

I am tuning the same sides high and low as original. I am changing frequencies. I tuned with tracking generator first time. The second time I tuned with signal generator and receivers. I am wondering if swr protect is shutting down the R1225 transmitter. I do not seem to have the notch affecting the transmitt frequency on transmitt cavity. There is no desense. I am using R2660 as load and wattmeter.

[Bill_G]

Okay. do it again with the sweep gen / spec analyser, use a dummy load on the open port. Tune for peak pass freq with the rods and dip the reject freq with the caps.

[arlojanis]

I connected two Bird meters in series with a very short cable. I watched both forward and reflected power and tuned the transmitt side for best forward and reflected. I now have 40 watts forward and almost 0 reflected into the duplexer and 27 out as read on R2600. This is progress. The receive side is terminated into Bird load.

[arlojanis]

Duplex operation is now good. Would alignment on sweep gen have been better if I had pads on cables? Would I need a pad on both cables to R2600? I always use the Bird load on other port. What is a good pad to use and is available on ebay?

[Bill_G]

I don't use pads. I adjust the gen output levels where I need them - about -30db to set the pass peak, and -10db to set the reject dip. I do one side at a time. I put the spec analyser on the ant port, shove gen output into the side I'm tuning, and put a small 50 ohm load on the open port of the other side.