Why am I missing channels w/ PRO LNB's?

[grynner]

Why am I missing channels w/ PRO LNB's? by teach and CoinBuck

1. Dish mis-alignment causing a lower signal strength than max available at your location. Re-align dish for max signal strength.

2. There is an INTERNAL electronic difference between how the LEGACY LNBs and the PRO LNBs work.

LEGACY LNBs are designed to pickup only one satellite's signals at a time. Under the "old" LEGACY LNB method, if one wanted to view 2 satellites, you'd use 2 separate LEGACY LNB's and combine their signal with an EXTERNAL SW-21 or the like so that 2 satellite's signals could be sent down one cable to a receiver. THESE HEADS WORK WITH VIEWSAT and other FTA boxes because of the ability to REMOVE the SW-21 from the cabling.

Later versions combined 2 LEGACY LNBs into a single unit (LEGACY Twins and Quads) AND added the required SW-21 switch INTERNALLY inside the case so that 2 satellite's signals could be sent down one cable to a receiver. THESE HEAD DO NOT WORK WITH VIEWSAT and other FTA boxes reliably because of the presence of the SW-21 which cannot be removed.

PRO LNBs (twin or quads) are actually 2 LNBs built into a single box. Instead of using a SW-21 to switch the signal from 2 satellites, a DiSEqC switch is used and 25,600 oscillator is installed INTERNALLY so that it can "stack" one polarity signal on top of the other polarity signal in order to send both satellite polarities from one satellite down one cable to a receiver.

Note: there are also DP single(or dual) LNBs used for 61.5 or 148 these are for one satellite only and are usually used in conjunction with a DP34 switch in DN setups, these will work fine with FTAs following DP guidelines.


These DIFFERENCEs are the reason those of us helping folks with their ViewSats constantly ask what TYPE of LNB are you using. You need to know your LNB type because the setup procedures are slightly different between the two--LEGACY and PRO.


And, YOU NEED TO TELL US "LNB TYPE" (LEGACY OR PRO) WHEN ASKING FOR HELP!


IF you use a satinfo.sat file NOT designed for PRO LNBs, you possibly can up 1/2 of the channels SHORT/MISSING with older ViewSat files; currently, PRO LNBs are reported working correctly!

Reason:
PRO heads "internally" stack the "H" Horizontal TP signal and the "V" Vertical TP signal in order to use only ONE CABLE to the STB/IRD. This is done with an oscillator in the LNB.

Hence, without the "H" HORIZONTAL TP conversion to a "V" VERTICAL TP frequency, PRO LNB's will NOT receive "H" TP frequencies and you will be MISSING 1/2 the channels.

MATH
Changing "H" TPs to "V" TPs

FORMUALA
"new" 'V' TP Frequency = 25600 - "old 'H' TP frequency

EXAMPLE TP DATA
119 TP2 (Leg) = 12239, 20000, H, 5/6 - LEGACY satinfo.sat info for TP 2 on 119 - AS A HORIZONTAL TP

119 TP2 (PRO) = 13361, 20000, V, 5/6 - PRO satinfo.sat info for TP2 on 119 - AS A "CONVERTED" HORIZONTAL To A "VERTICAL" TP

If you use a "standard" satinfo.sat file (i.e. comes packaged in V76.pgm as of 10-25-05) which is setup for LEGACY LNBs under the above example w/ PRO LNB's, you can see that the STB will not be tuned in to get that TP because of the WRONG info in the satinfo file.

Basically, you'll be missing 1/2 the available channels... and this is the reason for all the moaning and groaning about missing channels and PRO heads...

To complicate matters in a setup, once you have an incomplete channel scan in your ViewSat, the only practical way is to do a FACTORY DEFAULT to clear your channels and, then, to load a PRO satinfo file and re-setup your box.

Doing it "RIGHT" the first time will save you lots of time, effort and aggrevation and get you to testing out your new "toy" at the soonest possible moment.

Were do i get this pro satfile.