OTHER Invacom LNB Off Frequency

[cyberham]

My NOS Invacom SNH-031 universal LNB scans in frequencies about 11 or 12 MHz high. It's a very old LNB. This doesn't seem to affect its sensitivity which is fine. All transponders on the first satellite scanned were found. On my Edision receiver, I may be able to correct for this by setting an appropriate user-defined LO frequency in the receiver so the receiver reports a more accurate transponder frequency. But my GT Media receivers have no way to do this.

Can I adjust the actual LNB LO frequency without having anything like a frequency counter to monitor as I change the LNB? If not, this issue probably doesn't matter. I just need to think 12 MHz lower frequency when I look at a transponder.

 

[Titanium]

My NOS Invacom SNH-031 universal LNB scans in frequencies about 11 or 12 MHz high. It's a very old LNB. This doesn't seem to affect its sensitivity which is fine. All transponders on the first satellite scanned were found. On my Edision receiver, I may be able to correct for this by setting an appropriate user-defined LO frequency in the receiver so the receiver reports a more accurate transponder frequency. But my GT Media receivers have no way to do this.

Can I adjust the actual LNB LO frequency without having anything like a frequency counter to monitor as I change the LNB? If not, this issue probably doesn't matter. I just need to think 12 MHz lower frequency when I look at a transponder.

Yes, often a STB allows a user to enter a custom LO frequency. Shifting the LO will display a "corrected" downlink frequency. This works best with standard type (single LO) LNBs, as these do not require a switch point frequency to toggle between multiple LO ranges.

A signal generator can be used to provide a signal into the feedhorn via a tuned antenna stub, then the tuning slug can be adjusted with a non-metallic driver to output a correct IF carrier. A signal analyzer or an calibrated SDR can be used to view the generated carrier.

 

[cyberham]

Yes, often a STB allows a user to enter a custom LO frequency. Shifting the LO will display a "corrected" downlink frequency. This works best with standard type (single LO) LNBs, as these do not require a switch point frequency to toggle between multiple LO ranges.

A signal generator can be used to provide a signal into the feedhorn via a tuned antenna stub, then the tuning slug can be adjusted with a non-metallic driver to output a correct IF carrier. A signal analyzer or an calibrated SDR can be used to view the generated carrier.

On the Edision for this universal LNB, if I set both the LO-Low and LO-High to 10589 MHz (instead of the usual 9750/10600 MHz), then the switch point to 11689 MHz, this keeps the receiver happy. It will then blind scan 11539 to 12738 MHz. The resulting tp frequencies are exactly accurate.

So I lose some of the usual lower frequencies for the universal LNB scan (10700 to 11538 MHz) but there's nothing there anyway on most of the satellites I can see 150W to 72W.

I will avoid messing with tuning the actual LNB LO frequency.