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