Half-alive or half dead Mini-Tiouner?

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radiogareth
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Joined: Wed Jan 06, 2016 9:46 am

Half-alive or half dead Mini-Tiouner?

Post by radiogareth » Thu Dec 03, 2020 7:48 pm

This is a strange (and recent) fault that so far is defying my attempts at solving it.
My MT has been working fine for 18+months.....
Just recently, having re-assembled the home station and got 40 Watts to the POTY (pictures via Q100, sent and received fine at various symbol rates 125,250 an 333) I found I was getting stuttering (video and sound) on the beacon signal. OK on some occasions, others were reporting this too, but when they were NOT, I was still getting the problem. MT shows SR at 100, RF power about 43, MER 7ish, but carrier varies from 60-85.
Using Longmynd I get similar results - chopped up video, variable audio. Same with my Ryde RX. I've tried a different LNB in case my external reference unit didn't like my external reference (which was perfect on NB). I've tried battery power to the LNB, the original small variable PSU (so I could switch H/V) and my latest bias-box with DC upconverter in it. No difference. As a sanity check I'm running AMSAT DVBSGUI software using the same LNB signal as is fed to MT. I get 100% copy video and sound.
I've DC measured the MT, I have put a scope on everything that moves (electronically) and I cant see any problem with anything. I've resoldered the NIM and the USB FT2232H pins.
So I'm asking if anyone else has these (or similar) symptoms and if yes, how was it fixed? Unfortunately the Amsat software, whilst easy to get locked on the beacon, is a beast on anything else. SDRAngel only recognised my SDRPlay (receiver for the IF from LNB) about 1 in 10 times I run it - very frustrating.
There isn't much to go wrong. NIM, USB or PSU......has too much RF got into NIM perhaps? Shack leakage from the amp perhaps?
Gareth

g8gtz
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Re: Half-alive or half dead Mini-Tiouner?

Post by g8gtz » Fri Dec 04, 2020 8:50 am

Gareth,

Are you saying just the beacon or is it other QO100 signals you're having problems with?

If it is just the beacon then so I'm afraid you cannot rely on it as it is broken again....

Noel

radiogareth
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Joined: Wed Jan 06, 2016 9:46 am

Re: Half-alive or half dead Mini-Tiouner?

Post by radiogareth » Fri Dec 04, 2020 11:38 am

Hi Noel, its ALL signals....but beacon has been fine all morning via AMSAT GUI, doesn't miss a beat.Ryde is reporting a MER of 8+/-1 and D3+
Last night I was getting good MER and D on the net signals, but not a single decode on MT/Ryde. Neither could the AMSAT GUI but its so quirky I'm probably hoping for too much.
Found the wiring up diagrams for my MTPro2 so I'll assemble that and see what gives.....
Onward.....
Gareth

radiogareth
Posts: 1215
Joined: Wed Jan 06, 2016 9:46 am

Re: Half-alive or half dead Mini-Tiouner?

Post by radiogareth » Fri Dec 04, 2020 12:25 pm

Well that doesn't 'fly' - it seems MinitiounerPro2 needs different software, not freely available yet. Fair enough I suppose.
So I just tried across the shack on 437 and 1255. No problem, MT/Ryde locks up and give a steady picture.
I'll go back to Q100 and stick to strong signals, see if it can cope. Unless my dish/lnb is picking up some sort of pulsed interference, I am stumped...
Gareth

g0mjw
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Joined: Sat Sep 20, 2014 9:15 am

Re: Half-alive or half dead Mini-Tiouner?

Post by g0mjw » Fri Dec 04, 2020 12:54 pm

Perhaps is is the LNB. Sometimes there is a lot pf phase noise on modified PLL LNBs. Unmodified PLLs also can have issues too. It might be OK on one polarisation but not the other. Perhaps there is a problem with your reference? I would suggest you look at the signals coming out of it on a spectrum analyser.

Mike

g4hiz
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Re: Half-alive or half dead Mini-Tiouner?

Post by g4hiz » Fri Dec 04, 2020 1:34 pm

Gareth,

In your earlier posts, you mentioned that originally the Minitiouner/lNB setup worked fine. The question is what's changed ? You also mentioned that you had to tweak the DC/DC converter output to increase its output slightly, this has obviously changed. I would try disconnecting the DC/DC output and feed the regulators from an external DC input from a bench power supply at 4.7V and see if this makes a difference. From my experience, the DC/DC module used can be a bit sensitive and may have developed a fault.

73
Jen

radiogareth
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Joined: Wed Jan 06, 2016 9:46 am

Re: Half-alive or half dead Mini-Tiouner?

Post by radiogareth » Fri Dec 04, 2020 3:04 pm

Thanks Jen, although the output looks good on a scope, I'll give that a try......
OK, separate PSU, no difference :-(
I'm getting almost instant lock with good MER and D (5 & 2) on the big 1MS signal (PA2HOS) but no video.
Mike, LNB is a possibility, although the current unit was fine when last used. Unless the RF has messed up something (only 40W at the dish). I'll see what the SA shows.
I'll box it back up, having failed to find fault, unless there is something corrupting the incoming stream from the LNB, but as its a 'closed system' that should not be the issue.
Gareth.

g4eml
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Joined: Thu Apr 26, 2018 9:36 am

Re: Half-alive or half dead Mini-Tiouner?

Post by g4eml » Sat Dec 05, 2020 12:13 am

Someone else had a problem where they were getting good lock but no video. That turned out to be a bad connection to the USB module. Might be worth checking for shorts or open circuits.

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