Multiswitch, active multiswitch, diplexer

[deandec]

I am trying to solve a couple of different applications which has caused me to try to understand what these pieces of hardware do.

Multiswitch:

Seems to be an electrically powered switch that can expand two leads (or more) from a dual LNB into four leads (or more) without signal loss or voltage confusion. The multiswitch power comes from the DVR Sat receiver connections.

Active Multiswitch:

Same as above except needs an external source of DC power since the Sat Receiver does not provide enough power. Usually needed on older Sat Receivers.

Diplexer:

Can be used to combine a dual LNB's A & B coax leads to one single coax for a long run and then used on the other end as a splitter to recreate the A and B coax from the LNB so that the Sat Receiver know which is 18v and which is 13V?

Additionally, the Diplexer can combine an OTA signal with one of the LNB coax signals for a single coax run. A diplexer is then used to split those signals at the Sat receiver destination.

Also, the Diplexer can multiply the two leads A & B from the dual LNB into three or four single coax runs that combine the A & B signel.

Questions:

Did I get close to correct on the above descriptions?

If a 2x4 diplexer is needed at the antenna end (to create 4 single coax combined runs), is a multiswitch also required at the dish antenna?

Are newer passive multiswitches able to be used in place of a powered multiswitch that was required on older installations?



Thanks in advance for any clarifications or corrections.

[Jim_L]

Whereas I am not a technician and I am sure there are those out there, I will take a stab at the diplexer. It is my understanding that the diplexer is used when you have more than one frequency transmission. For instance, the sat signal is typically a different frequency from over the air or cable and therefore the use of the diplexer allows you to use one wire for multiple frequencies. Whereas I cannot speak for Dish Sat, I do not think that using Directv, you can carry the A and B through the one wire.

Use a diplexer on the input side of the wire to combine sat and over the air/cable and then another on the output side to split the signals back out. I do not think that a diplexer will carry both A and B sat signals since believe they are the same frequency.

The diplexers that I have seen are 2 in and 1 out and vice versa for the other end of the wire. I have not seen a 2x4 diplexer. Again, I am only speaking with limited knowledge of Directv, cable and over the air.

Good luck

[wa8yxm]

YOu are close.. A diplexer is normally used to combine an over the air antenna with a LNB.. You need two, one at each end. they can not combine two LNB's however as the frequency bands have to be different for it to work.

Now a STACKER will combine two LNB lines into one by translating one of the LNB's to a different frequency band.. You need a DESTACKER at the other end to sort them out.

The multi-switch does indeed take two LNB lines, and "Expand" them to more lines.. This is useful to run 3 or more receiver/tuners (Two DVRs = 4 Tuners) and that is where they are used.

Some info: Sat Television transmitters use what is called circular polarization to send twice as many signals in the same bandwidth (Each frequency is used TWICE)

With circular polarization the signal "Screws" into the antenna, much like a bolt screws into a nut.. As you may well know, epically if you drove Chryslers some decades ago, you can have both Right hand (Righty Tighty, Lefty Loosey) bolts and LEFT hand bolts (which work the other way around) (Chrysler used left hand threads on the wheel lugs on one side of the car back then.. A very good idea actually)

The LNB has two antennas. inside, A single LNB can choose the antenna and send either the ODD or EVEN Transponders down the line to the receiver.

A DUAL LNB not only has two antennas, but two sets of electronics behind them, Each set of electronics can choose the antenna to use, Right or left.

DirecTV (DirecHDTV is a bit different) uses voltage to select Odd or Even (Left/right) and both output in the same frequency band

If you have more than 2 receivers, and a DUAL LNB, then the switch sends low voltage to one cable and high to the other, and it will pick the line depending on what voltage it receives.

IN addition there are other switches.. .These work the other way (letting a single receiver use more than two options) Multi-LNB (TWIN, Triplet, Quint) have this kind of switch built in.. There are assorted ways of working these switches and I'm not up to date on them so I'll not describe them

DISH network does things a bit different, Since the standard (NOT HD) dish antenna is a TWIN (Two LNB Dual output) they "Stack" the odd and even (Right and left hand) transponders.

Stacking is what I call "Frequency Domain Multiplexing", (What can I say. I am a certified technician and that is one of those technical terms )

So if the receiver wants a station on Transponder 10, it looks at one frequency and if it wants transponder 11.. IT looks at a different frequency in a different band.

To choose which satellite (LNB) they use either control voltages or tones to switch a DSS switch in the LNB head (Digital Satellite System if you want to expand the initials)

Dish HD works the same way

Again a multi-switch can pick a line to send on to the receivers.

MOST dish receivers will work with an amazing varaity of switches and antennas.. They are intelligent devices and when you run CHECK SWITCH they try every possible signal and check the results, remembering the one that works.

DirecTV receivers need to be set up by the user.. So you need to know what antenna you have.. else it don't work.

[deandec]

Ok, thank you for the clarifications.

In the first application,
Direct TV with one coax to each of 3 DVRs but two coax wanted for each, it appears the Stacker solution gets too expensive for my SIL's taste. Scratch that project.

In the second application, my dome antenna manual says I need an "active" multi-switch to install a second Direct TV tuner/DVR. That one may get scratched unless I can find @ a $50 active multiswitch.

It is amazing what a neophyte can learn on these websites.

Thanks again, guys. for the information.

[wa8yxm]

In the DirecTV situtation you run two cables from the antenna (A dual or multi-LNB antenna) to the active multi-switch.. Then you run two lines from the switch to EACH DVR. The switch does the magic.

I have an active multi-switch I could be pursuaded to part with for little cash but I'm in South Carolina (About 3 miles from Georgia off I-85) It's an RCA, I"m told it's not one of the better switches.. Don't know how many outputs (think it's a 2x4,, that is 2 in and 4 out) but not sure.

If you are near the Georgia/SC border,, Drop me a line and I'll give it to you to try.

[deandec]

wa8yxm

Thanks for the offer, but we are on opposite coasts. I did order a $10 multiswitch just to see if it would run the antenna with my equipment. If it does, then I will rig up our DVR to travel with us and continue to use the old receiver to aim the antenna.

If not, I will look for the active MS to accomplish the same.

Too much time on my hands I guess.