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sinclair Q3220e could have a problem

 

I have a UHF site where out of nowhere I have a lot of problems with reception.

When I built the repeater I had great performance on receive and the tx was right where I wanted. I use a pair of kenwood radios, a TK-860GH as TX and a TK-862GH as RX.?

I then tuned the Q3220E and all was well. When I got it it was way out? of alignment?IT was flat on my desk and the pass had an insertion loss of -10dB the notch was no where it was supposed to be and the duplexer was supposed to have been tuned by a pro.

Anyone seen a problem with a duplexer of the model being ok when the face is on the ground and not being ok when flat as supposed to be in the 19 inch cabinet??

Cause when I took the duplexer, put?it?face down beside?my?test set and tuned it. all 4 covers on top of the caps were very hard to remove. and started tuning one side, with the other side terminated with a 50 ohm load. Then did the other side, left the duplexer face down and tested the performance of the whole system, all was fine. later on we put the system in place with the duplexer facing normally on the 19 inch rack. Power output was ok. And I did not have anyone to test from afar . So I did some tests with some people on the allstarlink networks, the audio was good. So I left it there.?

Now The repeater is?deaf. Someone 8 miles with 50 watt will open the radio but someone at 30 miles wont be able to do it, They all receive the repeater perfectly. with only 20 watt at the output of the radio before the duplexer.?

The only thing different than my setup at home is the antenna and line, and the position of the duplexer horizontal vs vertical at home. All the wires between the radio and duplexer are tagged for tx/rx and were the one used in the test.

I cant?bring my test set on top for the simple reason that it is way too heavy.?

Starting to think that I will buy a small rigol sa/tg for those?field trip.

Pierre VE2PF
 

Anyone seen a problem with a duplexer of the model being ok when the face is on the ground and not being ok
when flat as supposed to be in the 19 inch cabinet?
The tuning of many duplexers will change juuuuuuuust a tad when rotated from vertical to horizontal due to the position of the center conductor flexing slightly. Some, but not all, cavity resonators have a dielectric spacer that supports the center conductor to keep it centered axially within the cavity to help with this. Some will also shift a bit when rack-mounted as opposed to just laying on their side due to the difference in stresses - the T1500 series is a good example of this because they are mounted to the panel by the "neck" of the center conductor assembly. But, on a good, properly-functioning, duplexer, these shifts should be very minor...not like the gross change that you're seeing.

My guesses, in the order I'd consider to be most likely to least likely:

- bad piston trimmer cap that is shorting when oriented horizontally

- broken solder connection in loop assembly (makes/breaks connection with orientation)

- bad cable/connector in harness

- contamination in a connector (e.g. fragment of metal that shorts center to shield depending on orientation)

- contamination inside cavity

all 4 covers on top of the caps were very hard to remove
If any of them were so tight that you accidentally ended up rotating the body of the capacitor rather than just unscrewing the dust cap, there is a good chance that the capacitor was damaged.

I cant bring my test set on top for the simple reason that it is way too heavy.
"If the mountain will not come to Muhammad, then Muhammad must go to the mountain." Bring the duplexer back home to work on. The kinds of repair and tuning that are most likely required are not something you'd want to be doing on-site unless you have no other choice.

--- Jeff WN3A



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THanks?Jeff,?

the list of possibilities that you are giving me makes a lot of sense.?

I will have to take my large snow boot and small shovel, to go back to the site. Only a 100 foot shoveling if there is not too much snow.?
We did not have a lot of that down below where I live. Let's hope the top of the mountain was the same.?

Pierre
VE2PF

Le?lun. 25 janv. 2021 ¨¤?14:59, Jeff DePolo WN3A <jd0@...> a ¨¦crit?:
> Anyone seen a problem with a duplexer of the model being ok when the face is on the ground and not being ok
> when flat as supposed to be in the 19 inch cabinet?

The tuning of many duplexers will change juuuuuuuust a tad when rotated from vertical to horizontal due to the position of the center conductor flexing slightly.? Some, but not all, cavity resonators have a dielectric spacer that supports the center conductor to keep it centered axially within the cavity to help with this.? ?Some will also shift a bit when rack-mounted as opposed to just laying on their side due to the difference in stresses - the T1500? series is a good example of this because they are mounted to the panel by the "neck" of the center conductor assembly.? But, on a good, properly-functioning, duplexer, these shifts should be very minor...not like the gross change that you're seeing.

My guesses, in the order I'd consider to be most likely to least likely:

- bad piston trimmer cap that is shorting when oriented horizontally

- broken solder connection in loop assembly (makes/breaks connection with orientation)

- bad cable/connector in harness

- contamination in a connector (e.g. fragment of metal that shorts center to shield depending on orientation)

- contamination inside cavity

> all 4 covers on top of the caps were very hard to remove

If any of them were so tight that you accidentally ended up rotating the body of the capacitor rather than just unscrewing the dust cap, there is a good chance that the capacitor was damaged.

> I cant bring my test set on top for the simple reason that it is way too heavy.

"If the mountain will not come to Muhammad, then Muhammad must go to the mountain."? Bring the duplexer back home to work on.? The kinds of repair and tuning that are most likely required are not something you'd want to be doing on-site unless you have no other choice.

? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? --- Jeff WN3A



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