DSD720i RF issue

[ponder]

Scenario:

Antenna--->Booster--->DSD RF(in)--->DSD RF(out)--->Splitter--->Tv's

The compact decoder gave up the gost the other day after the eskom power kept going on and off.
Found old dsd720i in cupboard and installed it. The problem is heavy noise/snow on the dstv channel, sabc1/2/3 & etv are clear.

Connected signal directly from booster to tv and the signal is crystal clear.
Disconnected RF(in) from DSD only running RF(out) to splitter and all tv's have a clear dstv picture.

I cannot have both at the same time although this worked fine on the compact decoder.

My only conclusion is there is not enough frequency seperation between the incoming signal from the booster and the dstv output signal causing the interference.

Is there any setting on the DSD720i to shift the output frequency? I also opened the DSD720i to look at the modulator hoping it would have an adjustment screw like in the old days but saw nothing.

 

[Gambit]

You probably find the new digital terrestrial broadcast signal is using the same frequency as the DSD. You can change the output uhf channel by either holding down the uhf button (small yellow one if I recall) on the remote for a few seconds or going through the menu system. (advance options->tv installlation->uhf tuning pin=9949)

 

[Quantum Theory]

Try putting the booster/setback amp after the decoder. At the moment it is amplifying the incoming terrestrial and not the decoder signal, leaving the terrestrial signals higher than the decoder's... just a hunch

 

[Gambit]

Try putting the booster/setback amp after the decoder. At the moment it is amplifying the incoming terrestrial and not the decoder signal, leaving the terrestrial signals higher than the decoder's... just a hunch

This depends on when he says "booster" does this mean a masthead amplifier on the antenna or a setback amp. If it is a masthead amplifier then it is in the correct position otherwise if it is a setback amp then it should be moved. However if all the terrestrial channels are clear then I still believe it to be interference from the new digital transmissions. In cape town we had problems with a lot of dstv decoders setup on the same frequency as the dtt signals.

Here is the info from the dstv website:
http://www.dstv.com/dstvsa/content/en/dstvsa/DTT_transmitter

 

[Quantum Theory]

This depends on when he says "booster" does this mean a masthead amplifier on the antenna or a setback amp. If it is a masthead amplifier then it is in the correct position otherwise if it is a setback amp then it should be moved. However if all the terrestrial channels are clear then I still believe it to be interference from the new digital transmissions. In cape town we had problems with a lot of dstv decoders setup on the same frequency as the dtt signals.

Here is the info from the dstv website:
http://www.dstv.com/dstvsa/content/en/dstvsa/DTT_transmitter

Off course, you could be right... but neither of us have enough info, to be 100% certain that we are right in our diagnosis. Could also be that the RF out on the old decoder is faulty. I still feel that my hunch is right. I feel like House MD right now...

 

[ponder]

However if all the terrestrial channels are clear then I still believe it to be interference from the new digital transmissions.

But why did this not happen with the compact decoder?

Thanks for info so far everybody, I will have another look tomorrow.

 

[Gambit]

But why did this not happen with the compact decoder?

Thanks for info so far everybody, I will have another look tomorrow.

The compact decoder was probably set to output its signal on a different uhf channel to the 720 decoder. If you had to retune your tv to view the 720i decoder then this is the mostly likely scenario.

 

[ajax]

The compact decoder was probably set to output its signal on a different uhf channel to the 720 decoder. If you had to retune your tv to view the 720i decoder then this is the mostly likely scenario.

Yes, change the UHF output channel of your decoder and retune all the tv's. Lowest channel is best because the cable loss will be lowest. Check on Sentech's site for the channel numbers of your terrestrial transmitters that you don't choose one of them.

 

[ponder]

You probably find the new digital terrestrial broadcast signal is using the same frequency as the DSD. You can change the output uhf channel by either holding down the uhf button (small yellow one if I recall) on the remote for a few seconds or going through the menu system. (advance options->tv installlation->uhf tuning pin=9949)

Siyabonga k@kulu!

Did not even know about that option. Moved the output Ch69/855Mhz and all is well again after retuning the tv's

Edit: Holy crap the language filters do not smaak isiZulu. Racist agents!