If you're new to DBS (Direct Broadcast Satellite), you're probably confused by some of the acronyms and abbreviations bantered about by those of us who have learned to speak the lingo. So here's a page for you. I promise to keep the complicated stuff to a minumum here until you're ready to move on.
 

• Glossary of Terms and Abbreviations
• Geoff Trowbridge's excellent DBS Introduction.

What is an LNB, or is it LNBF?

LNB(F) stands for Low Noise Block downconverter with integrated (Feedhorn). Either acronym may be used in the small dish world. It is the final stage of the antenna, and the first stage of the receiver. It comes in single and dual units. A dual LNB is just like two singles in the same case. Each half is independant of the other. Inside is the detector and downconverter electronics, along with circuitry designed to switch the LNB from right hand circularly polarized to its opposite. Adjacent transponders on the satellite use opposite polaritization to prevent adjacent channel interferance. The widely used Twin and Quad each have 2 dual LNBs along with an integrated switch.

Warning! Warning! Warning! Boring technical details with superfluous history lesson follows:

For those who care to know, a "block converter" is simply a device that converts a block of radio frequencies (in this case the 12.2-12.7GHz DBS satellite signals) to a different frequency (in this case 950-1450MHz) useable by the receiver. 12GHz signals wouldn't survive through 10 feet of RG-6, never mind 100! The lower frequencies are much easier to work with.

To bore everyone further, LNB is not technically "short" for LNBF, since LNBs CAN come without feedhorns, like on most C-band (big) dishes, where the C-band (or Ku band or both) LNB bolts to the feedhorn on the dish. All DBS LNBs I've ever seen have the feedhorn built-in, so the "F" is essentially unnecessary, just like the "A" (all LNBs have amplifiers, yet we don't call them "LNABs"!)

In the "old days" the low-noise amplifier and downconverters were separate units, so the amplifier was called an "LNA", which then plugged into the downconverter with a really thick chunk of short RG-11 cable, before feeding into the house on RG-59 (typically.)

Eventually the LNA and converter merged into one unit, which back then was either called an LNB or LNC depending on whether you thought "Block converter" or "Converter" deserved an initial. LNB finally stuck. Satellite "old-timers" still often call LNBs LNAs, the same way our grandfathers still refer to refrigerators as "ice boxes."

See: http://www.switchinfo.info/lnbs.html for some more info and photos of Dish's LNBs.
 

What is a Transponder? On the installation screen I've noticed that my transponder number changes.
Some numbers have different signal strength than others. Today transponder 05 I can 99% signal strength. Yet 13 for example has 86%. Why is that?

A transponder is the transmitter/antenna on the satellite. Typically a satellite will have around 32 transponders, although the owner of the satellite may not be licensed for all 32. Each transponder operates at a specific frequency, and can carry from 1 to 8 channels of TV and audio. Even and Odd transponders operate with opposite circular polarization to prevent adjacent "channel" interference. When you go to the installation screen, the transponder shown will be the one carrying the program you were last watching. You can not choose to have your program come across a different transponder. Several of the transponders on some of the satellites are operating at double power, and this accounts for some of the difference you are seeing. Other transponders might have different effective strengths at different geographical locations within their footprint. But there's not much point in being concerned, almost any strength over 50 gives you a perfect picture. Higher strengths just give you some margin against rain and snow fade.