Ok. I understand. But this problem never occurs when i'm using a normal receiver. It only occours when i'm using my tv card.

Receivers and dvb-cards are very different and can not be compared ...

You're talking about warming up a LNB. Do you mean switching on a station with a transponder like 12530, H, 22500, 5/6 and stay a half hour on this station?

P.S. I'm using a LNB with two inputs.

I´m talking about the senibility of the tuner from DVB-cards and Receivers ...tuner of receivers are considerably better then the ones fron dvb-cards ...

redbull86 wrote:You're talking about warming up a LNB. Do you mean switching on a station with a transponder like 12530, H, 22500, 5/6 and stay a half hour on this station?

P.S. I'm using a LNB with two inputs.

Yes, sure.
Does not have that one, but should be horizontal, by this feeding with 18 Volts and causing some more power consumption than on 13 volts.

This does not have to be done over the port of your DVB card, the receiver could do this job as well.
Just have the LNB being powered up some time before making any tests.

Most computer DVB tuners are not only less sensitive, but even seperation filters and AFC and AGC controls are less effective, and driver( interface)s are worse than real hardware controls of STBs.
This for it's no wonder that reception is generally weaker, and proper settings are much more important.

Main reasons for differences are tolerable power consumption and highly integrated circuits, which won't allow relatively big passive filter components but use mathematical tricks instead in chip tuners.
And that's the main reason, why people should not believe in recommended dish sizes, as those are meant for standard tuners.
Sensitivity of most computer DVB tuners may be compared with cheapest old analogue stuff, not with modern digital equipment...

That's my point of view as a TV mechanic.

Juergen wrote:

redbull86 wrote:You're talking about warming up a LNB. Do you mean switching on a station with a transponder like 12530, H, 22500, 5/6 and stay a half hour on this station?

P.S. I'm using a LNB with two inputs.

Yes, sure.
Does not have that one, but should be horizontal, by this feeding with 18 Volts and causing some more power consumption than on 13 volts.

This does not have to be done over the port of your DVB card, the receiver could do this job as well.
Just have the LNB being powered up some time before making any tests.

Most computer DVB tuners are not only less sensitive, but even seperation filters and AFC and AGC controls are less effective, and driver( interface)s are worse than real hardware controls of STBs.
This for it's no wonder that reception is generally weaker, and proper settings are much more important.

Main reasons for differences are tolerable power consumption and highly integrated circuits, which won't allow relatively big passive filter components but use mathematical tricks instead in chip tuners.
And that's the main reason, why people should not believe in recommended dish sizes, as those are meant for standard tuners.
Sensitivity of most computer DVB tuners may be compared with cheapest old analogue stuff, not with modern digital equipment...

That's my point of view as a TV mechanic.

Thanks for the explination. I tried this out and what i saw is that the transponder that worked before warming up the LNB is not working. When i shutdown the pc and start it up after 2-3 hours the transponder worked again.

This happens only with some transponders (not every transponder) with a symbolrate between 2050 and 3000 MHZ. Other transponder with a symbolrate of 3000 or higher never have this problem.

In fact that low symbol rate (split) transponders with SCPC signals are extremely critical to tune in properly.

Are there several of those pretty close to each other, within a range of around 30 MHz?
If so, they are supposed to share the same physical transponder up on that bird, by this also dividing the power and perhaps interfering with each other on your tuner a bit..
And even a neighbour signal may cause trouble, if once active and next time inactive.
Reduced RF power will make things even worse.
Generally, SCPC signals are not meant to be received by hardware like ours but with special STBs, so our results aren't always reliable. Possibly a bigger or perfectly aligned dish (including skew / LNB tilt) may help, or a more stable new LNB.

Does ProgDVB support network search?

No, not yet.

But this won't help for feed hunting or your specific SCPC trouble at all, because this would only deliver true transponder frequencies (of the participants of that network), and it will not include temporary feeds, CCTV and alike.
Anyway, for NAT searching, a set of seed channels would still be necessary, instead of or additional to the common transponder lists.
Did play with this on DVBsVCR2 for quite some time, but have always been missing several transponders on each position, I've tested with.
And if started with a 3rd party list or manually entered channels, you would find many doublets or semi split transponders, due to different frequency value precision and rounding.

So, if ever, this should be just an additional option, no more.

So the only thing i can do is buy a new LNB? or do you have any other advice?

Before that, compare with some other software, to be as sure as possible.
But yes, this looks pretty much like an LNB issue now

Thermal LOF stability is important, far more than fantastic resp. fictional low noise figure values...

How can i know that the thermal LOF stability of a new LNB is OK?

Such tolerances and similar specifications may be available from data sheets, many of those can be found on manufacturer pages as well.

Other possibly helpful hints are case surface versus power consumption, as the power consumption results in thermal energy in the end, that has to leave the case someway, to not heat it up too much.
This also means, a metal outer case is supposed to have a better cooling effect than plastic.
BTW, dark materials take up more heat from the sun radiation.