How does a TV splitter work?

No I don't mean the theory of how it works, I mean how does it work in practice. The thing that brings this up is that I just hooked 2 TV antennas in parallel using a standard TV splitter. The way a splitter works of course is that you hook a signal source up to the input connector and it comes out the 2 (or more) outputs a little over 3 dB (or more) down. In this case of course I hook the sources (the 2 antennas) to the output connectors and get the 2 signals out together on the input connector. The question that came to mind is; Does this work the same way? Do the output signals come out a little over 3 dB down? My first thought is that they do. In fact thinking about it I suspect that a signal applied to any port will come out the other 2 ports a little over 3 dB down. But I don't know that and don't have the equipment to test it. So, does any body know?

Bill

Reply to
Bill Gill
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If the antennas are facing the same direction and are the same model you have created a 'stack' and will achieve +3dB and more directivity. If the antennas are in different directions you'll get 'random' phase cancellations. They are not actually random but can get so complex it appears to be. If you're trying to combine different directions you might look into 'jointennas' which are frequency selective diplexers. They're pricey but may help reduce the interference giving you one feed with all channels active and no rotator.

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Reply to
stratus46

snipped-for-privacy@yahoo.com wrote: ...

I think you might mean, "chaotic."

Cheers! Rich

Reply to
Rich Grise

To use it in practice, you need to know what you're working with.

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Hope This Helps! Rich

Reply to
Rich Grise

That really isn't a problem. The 2 antennas are at right angles to each other, and the yagi is fairly high gain. So it doesn't receive the signals from the side at all well. That is why I put in the second UHF antenna (a coat hanger antenna made to the plans readily available on the web). The result is that I get the same good reception on the major channels (ABC, CBS, NBC, and Fox) that I was getting on the main antenna, which is pointed at all those transmitters plus much better reception on all the UHF channels which are scattered all around the area.

My main thing was that I am curious just how the splitter works.

Bill

Reply to
Bill Gill

Bill Gill Inscribed thus:

Basically there are two types of splitter/combiner, resistive and tuned. In either case the idea is to combine two or more signals into one feed line whilst maintaining impedance matching, hence the nominal 3 Db loss.

Resistive splitter/combiners are generally not frequency sensitive whilst tuned ones are. A simple tuned splitter/combiner could be made out of three lengths of co-ax cable or 300 ohm ribbon.

Whilst mechanically simple, calculating the parameters for the lengths of co-ax or ribbon needed for a tuned splitter/combiner, is not !

Doesn't Wikipedia cover this ? I'll have to take a look...

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Best Regards:
                          Baron.
Reply to
Baron

Baron Inscribed thus:

Seems its called a "Diplexer" on Wikipedia.

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Best Regards:
                          Baron.
Reply to
Baron

"Baron"

** Absolute nonsense.

Passive spitters all use tiny transformers that are wide band.

.... Phil

Reply to
Phil Allison

"Phil Allison" wrote in news:9h60r0F6n9U1 @mid.individual.net:

tuned.

** Absolute nonsense. I have looked inside al of them I came across, and found two types, the first(cheapest ones) had the centres brutally soldered together, ignoring mismatch. Second type: from the feedline two 75 ohms resistors to the two outputs, thus keeping impedance at the correct level, accepting a bit of attenuation. The type you mention, would be the best solution, but I have yet to come across one of them, they are expensive, and for wideband use, lke ~60 tv channels, unusable.
Reply to
Sjouke Burry

Well, I guess that is just one of those questions that nobody has thought about, or at least hasn't investigated. I tried Rich's list at Google and didn't find anything that answered my question. There may be an answer in there someplace, but it is way down. I had just hoped somebody here would know the relationship between the

3 ports. I still think that a signal that enters any of the 3 ports will be split between the other 2 ports 3 dB down.

By the way, a diplexer is not a splitter. It works to combine signals at different frequencies for transmission on a single cable.

Thanks, Bill

Reply to
Bill Gill

"Sjouke Burry" "Phil Allison"

** You must live in a real backwater.

** Never seen one of them for forty years.
** You must live under a rock.

** ROTFL !!

They sell for a couple of dollars.

** ROTFLMAO !!!

Typical spec is from 50Mhz to 760Mhz.

Piss off fool.

... Phil

Reply to
Phil Allison

"Bill Gill"

** Like hell.

** Like any transformer, there is a ratio between the inputs and outputs.

An ideal two way splitter creates two signals from one, each 3 dB down.

Used in reverse, you need two inputs that are identical to get the 3dB boost that is possible.

30 years back, I used a 4 way TV splitter to combine 3 antennas operating on VHF that were not co-phased.

This was followed by a two way splitter to get two signals.

It worked like a charm for a pair of 202MHz radio mic receivers.

... Phil

Reply to
Phil Allison

I'm afraid that isn't quite correct. When a signal is split half the power available at the input is directed to each output. That is what makes the typical 3 dB drop from input to output. Well, actually it is a little over 3 dB, because of circuit losses. Now, if you reverse the signal flow direction you will transmit the

2 input signals (into the output connectors) to the output (input) connector. The max that you could get from either input would be the same level that was at the input minus circuit losses. If you put the same signal, same frequency and in phase, into both inputs you would get the sum of the 2 input signals at the output. But, my hypothesis is that in fact the 3 ports are essentially a Y circuit. In that case any input into any port would appear 3 dB down at the other 2 ports. It would be easy enough to check if I had a signal generator and a power detector, but I don't so that is why I asked here.

Bill

Reply to
Bill Gill

** Oh really ??????

Do you come here to ask others for info or just to be a smug prick yourself ??

No answer needed.

** Same as what I wrote.

Well,

** Did you see the word "ideal " ??????
** That is what I wrote.

** Nope.

That is a bonkers idea.

Piss off.

... Phil

Reply to
Phil Allison

I wouldn't trust a TV splitter to be much more than a center-tapped 2:1 impedance transformer (if that). If so, then pumping power into one port will give you a lot of leakage out another. Really cheap Chinese splitters will just be a couple of resistors, or in extreme cases, a black plastic block with nothing inside.

"Real" radio splitters start at "hybrid splitters" (or hybrid combiners) and get more fancy from there.

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Reply to
Tim Wescott

Good splitter/combiners are directional couplers, to provide isolation between the ports. Without isolation, you will feed part of each antenna to the other and re-radiate it. It was one of the parameters we tested from every vendor that wanted to sell us CATV hardware. A 'Return Loss Bridge' is easy to build. It is used with a TV Field Strength Meter' and a fixed signal source at the desired frequency. You also need a 1% 75 Ohm terminator for the unused port for the tests.

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Reply to
Michael A. Terrell

Google is your friend:

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JF
Reply to
John Fields

Well, looking at the last diagram I would assume that my hypothesis is correct, but at the same time it doesn't really discuss what I have been saying.

Thanks, Bill

Reply to
Bill Gill

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Then go to:

http://www.linear.com/designtools/software/
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Reply to
John Fields

ost

on

Hi Phil, I've got this cute little splitter from mini-circuits. ZSC-2-2. I wanted to know how the thing worked. I opened it up and tried to trace the wires. (Two transformers on toroid) with a resistor and two caps?) But I couldn=92t figure it out. Any idea how one of these is wired together.

Here's a rather poor picture.

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George H.

Reply to
George Herold

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