Mixing CH3 & CH4 RF Signals

[gpenzenik]

I have a four D* receiver setup. Dual thingy dish, multi switch and lots of pretty silver connectors on miles of RG6.
Everything is A OK with the system.


For reasons that are WAY to complicated to explain without beer I want to take two of the receivers, set ones RF output to CH3 and the others to CH4. Then mix the RF outputs and distribute that signal to multiple TV's.

Fast forward a bit.


I set up one D* receiver on CH3 and the RF distribution system, test it out and all TV's get the signal.



Now hook up second D* receiver on CH4 and now CH4 signal is great on all TV's.



But now the TV's that had a good CH3 picture have a really bad herring bone pattern.



So....

CH3 alone, all is good.
CH4 alone, all is good.

CH3 + CH4 and CH3 is blown out.

So do I need to pad the CH4 RF signal?
If so how do I tell by how much.
Or is something else up?

 

[Newshawk]

Now you know why the FCC never allowed a ch 3 and 4 to exist in the same market when they set up the original channel alignments!

 

[Raydr]

Now you know why the FCC never allowed a ch 3 and 4 to exist in the same market when they set up the original channel alignments!

What he said.


More specifically, the reason why you have this problem is because the cheap RF modulators you buy in stores are not meant to work like this. They are not built strictly, and therefore have a certain amount of "bleedover" into other frequencies.

 

[Raydr]

BTW, I did accomplish this with a little bit more expensive modulator.

I had one regular IRD, a Tivo, and a DVD player on three different channels. One was channel 67, one 69, and one 71. As long as you have at least 1 channel of seperation, you should be fine.

A google search for "dual rf modulator" turned up this:

http://www.accessorywarehouse.com/signal_distribution/modulators/index_modulators.htm

You can also find this stuff on eBay pretty cheap. Save yourself some hassel in the future and buy yourself a triple or quad modulator.

 

[boba]

To combine the outputs of two receivers the best way is use ch. 3 or 4 from one receiver and use a UHF/CABLE modulator connected to the A/V outputs of the second receiver. This is what DISH is doing with the 322/522 receivers.

 

[ZawNH-VT]

I have a four D* receiver setup. Dual thingy dish, multi switch and lots of pretty silver connectors on miles of RG6.
Everything is A OK with the system.


For reasons that are WAY to complicated to explain without beer I want to take two of the receivers, set ones RF output to CH3 and the others to CH4. Then mix the RF outputs and distribute that signal to multiple TV's.

Yes, it can be done very very cheap. What you need is a SC4 or SC3 conbiner.
I do those all the time for customers who want to hide their receivers in basement somewhere.

http://www.consumerdirectonline.com/sc4.htm Not saying buy from that website but that's what you need. May be a TA-15 AMP as well. This have 3 Coax port on there.


Let say you're using a SC-4 Conbiner. Set one receiver to ch3 and other ch4 like you would do.
Hook up the CH 3 out put from receiver to "Off Air/Ant In" port. CH4 receiver to CH4 port on SC4. Connect the spliter to "To TV Sets" ports..

Some cases I just use a 2 way spliter backward to achive this. doesn't work with all splitters thought.

 

[ScottChez]

Help me under stand this.

The SC4 will correctly seperate the Channel 3 and channel 4 signals and send them down the coax so they do not bleed over and cause interference on the other channel?

In other words Channel 3 wont mess up channel 4 with one of these boxes?

Looking at the price is it cheaper to get a Dual RF mod?

 

[Chris Freeland]

Help me under stand this.

The SC4 will correctly seperate the Channel 3 and channel 4 signals and send them down the coax so they do not bleed over and cause interference on the other channel?

In other words Channel 3 wont mess up channel 4 with one of these boxes?

Looking at the price is it cheaper to get a Dual RF mod?

If I am not mistaken, to do this you will also need a SC3 channel combiner too, this may or may not be cheaper then buying 1 uhf/cable tv modulator.

 

[ZawNH-VT]

No, just one SC4 conbiner.

Simple. set one ird to ch 3 other to ch4.

Connect the ird set to ch4 to CH4 input of SC4. IRD with channel 3 to Ant In and connect the Out to TV's to dist.

It works flawlessly for every customer who wanted to have it done cheap.

Actually I think they were originnal designed to combine Off Air Ant channel with VCR/DSS/BUD that modulate on channel 3 and 4 to home distbution systems. Well there is either one Channel 4 or Channel 3 in one DMA so they make SC4 for markets with Channel 3 off air. and SC3 for markets with CH 4 Off air so you can watch off air and satellite without using of receiver's power by-pass feature to watch Off Air channels.


No inteference on any of the channel with TruSpec SC4.

 

[gpenzenik]

My Ghetto Sparts bar is da' bomb

Got the sc-4, and now I've got two sports channels on every wall in my ghetto sparts bar, AKA my basement rec room on my $5 a piece hotle auction TV's!

 

[ScottChez]

I got one of the SC4 conbiner.

Works great, and its cheap.

Thanks for the info!!!!