I got myself a new toy to play with: a Radyne QAM-256 modulator!
Of course I already have three Dektec modulators in my laboratory:
- DekTec DTA-215 Gold (Product page at DekTec)
- DekTec DTA-2115 (see my test report at DekTec)
- DekTec DTU-315 (Product page at DekTec)
But still I wanted to have a professional grade modulator for continuous operation. The Radyne QAM-256 was offered at eBay at a very modest price, one of the reasons being that the seller did not manage to get it to work. That didn't necessarily mean it was broken, though one never knows.
Anyway, I won the auction, the seller was very pleasant to talk to (his hobby is to actually run an amateur TV channel - check it out HERE) and when the device finally arrived, I wasn't able to produce a QAM signal, either.
After a lot of trials, using two Deviser field meter (S7000 and S7200 - one to output an ASI stream, the other to analyse the RF signal at the test port of the Radyne QAM-256), I came to the conclusion that several things were wrong. I could see the transponder being generated at the correct frequency, but no constellation diagram could be rendered.
I therefore decided to open it up and see what was the problem.
Diagram of the SNAPHAT. It snaps on top of a RAM IC. While I ordered a replacement part (5-15 Euro, depending on where you buy it), it has not arrived, yet. So I did a small hack: I just connected two thin wires to VBAT- and VBAT+ and connected them to a CR3032 Lithium battery. It worked like a charm and now the settings are correctly stored, when the device is turned off.
This is of course a temporary fix, until the SNAPHAT arrives.
After all these small repairs and fixes, I was able to produce a propper constellation diagram, but though I got a lock on the signal, I was not receiving any data. I was disappointed and mentally preparing myself for the fact that the device was somehow defective beyond repair (at least without spare parts and documenation), when I got the idea to look at the constellation diagram with my Kathrein MSK33.
This field meter, despite being a little old by now, features the best constellation diagram I ever seen on a field meter. This is because of two reasons: 1) the constellation diagram is rendered without a lock on the signal and 2) it is really fast and by this I mean fast as in lightening fast!
- Topreal TP-1011 satellite receiver with ASI ouput port
- Dexing NDS3975 satellite receiver and multiplexer (see my test report at TELE-audiovision here)
- Radyne QAM-256
- Tiernan TDR60 satellite receiver
- Cableword MPEG modulator (see my test report at TELE-audiovision here)