LNB Drift

[iccoldbeer]

Is it possible to adjust dro lnb for drift by removing cover and if has brass screw going into dro cavity turn to adjust? Frequency adjusted like resitance is with a pot? Then after corrected reseal cover.I noted aprox 4mgz drift wile scanning the tightly grouped 3953-3976V on SES1 101W. I have several replacement lnbf if it gets messed up. And might use it as excuse to justify purchase and replacement with chapparal 1329 and pair of norsats, lol.Is the commercial equiptment realy worth the large $s?

[Terryl]

I would not adjust anything inside the LNB, what your looking at is the circulator, this mixes all the polarity's on the incoming side with the LO, adjusting this without a spectrum analyzer would cause all sorts of problems. And maybe even FUBAR the LNB....If it's drifting then the LO is shot and a new LNB is needed.

And the commercial stuff is better, but costs a ton more

[el bandido]

What receiver and lnb are you having problems with? Make/Model?

I learn by doing, so I would turn the screw just to see what happens. That is how I learn how and why things work. You will probably find the only thing that changes is the l.o. frequency.

[iccoldbeer]

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[el bandido]

There are only a few production lines in China that make the cheap c band lnbs you mention. So more or less, they all come form the same place, and maybe even the same line.

DRO lnb drift was not mentioned much until somebody saw there was nothing new to sell and decided to introduce the cheap pll lnbs. I have cheap dro lnbs that are over 10 years old and they do not drift enough to notice. I have some commercial dro lnbs that are about 25 years old and they do not drift enough to notice. All of this is not to say that dro lnbs cannot drift enough to notice because it can happen, but usually the drift of a dro lnb will not be enough to really notice.

There were some videos at one point for the defunct WSI company that showed the l.o. being set on a production line of lnbs. The tuning slug you mention was being adjusted, so I doubt you would change much except mess the l.o.frequency up if you move that slug. Maybe look at little bit more, and compare with some of your other items and see if the lnb is as bad as you think?

The three transponders you mention on 101W are tough for many receivers or cards. I do not know what exactly those transponders are transmitting, but some of my fta receivers can get "confused" as to what is supposed to be on those transponders. If the lnb is actually drifting bad enough to notice, the blindscans will be producing different numbers for the transponder on almost every scan. I would suggest looking at other things before deciding the lnb is at fault. And it also sounds like you got those lnbs at a good price. If this is true, not much would be lost if you did turn the adjusting screw and it made the lnb useless.

[iccoldbeer]

Was to quick to fault lnb. Did some checks on weekend. Lnb is fine just something about that group of channels that i must add couple Mhz in transedit, DVBviewer and DVBDream. It is the same with both tuners but Crazyscan finds 3 of them at reported frequency but misses 1 in middle. I will just add the couple Mhz and be content all 4 scan in. Did not have this prior to adding H&I west.
Thanks Terryl and Bandido

[el bandido]

Those dro lnbs hardly ever give any trouble. Usually, either they work or they do not. I have lost a few to electrical storms, but cannot remember replacing one due to frequency drift.

Glad you got it working!