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[Philip Roberts]

For building up small systems (4-8 receivers) used in relatively rural areas what down sides are there to using standard/cheap CATV splitter in place of a more expensive splitter?

Thanks

Philip

[Pete Erskine]

For building up small systems (4-8 receivers) used in relatively rural areas what down sides are there to using standard/cheap CATV splitter in place of a more expensive splitter?

Thanks

Philip

Shouldn't be a problem up to about 4 RX with antenna lines <50'.

[Russell Ault]

Shouldn't be a problem up to about 4 RX with antenna lines <50'.

Hi Pete!

Can you explain this a little further? Why only up to 4?

Thanks!

-Russ

[Pete Erskine]

Hi Pete!

Can you explain this a little further? Why only up to 4?

Thanks!

-Russ

Passive splitter/combiners, unless you spend $ have loss.  The more inputs you try to combine at the same time the more loss.  Including the antenna cable the loss can become great enough to make your RX or TX perform noticeably poorer as opposed to a single antenna in the device.

[Russell Ault]

Passive splitter/combiners, unless you spend $ have loss.  The more inputs you try to combine at the same time the more loss.  Including the antenna cable the loss can become great enough to make your RX or TX perform noticeably poorer as opposed to a single antenna in the device.

Ah, okay, I was assuming that an 8-way CATV splitter had to be active, but that's obviously not the case. That being said, what are your thoughts on using unity gain active CATV splitters for RX antenna distro?

Thanks!

-Russ

[Pete Erskine]

Ah, okay, I was assuming that an 8-way CATV splitter had to be active, but that's obviously not the case. That being said, what are your thoughts on using unity gain active CATV splitters for RX antenna distro?

Thanks!

-Russ

Probably not good,  try it though.

[Russell Ault]

Probably not good,  try it though.

I'm in the process of organizing the equipment to do just that, based off what was done here (although I'm planning to use Sennheiser antennas).

Before I spend someone else's hard-earned money on this project, though, I'm trying to think of a reason why it wouldn't work, and so far I've come up blank. The impedance mismatch issue is really a non-issue on the receive side (as discussed, I believe, elsewhere on these forums), and a unity-gain split won't over- or under-drive the receivers. If I understand this correctly, it all hangs on the quality of the amplifier in the splitter, but wouldn't something that passes analogue and DTV signals without problems also pass UHF microphone signals equally well (radio waves are just radio waves, after all...)? Am I missing anything?

Of course, what I'd really love is for someone here to show me why this won't work before I start my experiments, especially since I haven't hit the "purchase now" button yet. 

Thanks!

-Russ

[Keith Broughton]

Of course, what I'd really love is for someone here to show me why this won't work before I start my experiments, especially since I haven't hit the "purchase now" button yet. 

Thanks!

-Russ

You could contact the Sennheiser or Shure engineers and ask them.
I know they want to sell gear but think of this, if the CATV splitter works, why don't you see it in any wireless mic racks?

[Henry Cohen]

I'm in the process of organizing the equipment to do just that, based off what was done here (although I'm planning to use Sennheiser antennas).

Before I spend someone else's hard-earned money on this project, though, I'm trying to think of a reason why it wouldn't work, and so far I've come up blank. The impedance mismatch issue is really a non-issue on the receive side (as discussed, I believe, elsewhere on these forums), and a unity-gain split won't over- or under-drive the receivers. If I understand this correctly, it all hangs on the quality of the amplifier in the splitter, but wouldn't something that passes analogue and DTV signals without problems also pass UHF microphone signals equally well (radio waves are just radio waves, after all...)? Am I missing anything?

Of course, what I'd really love is for someone here to show me why this won't work before I start my experiments, especially since I haven't hit the "purchase now" button yet. 

As you've surmised, the primary issue will be the quality of the amplifier. What are its 1dB compression and IP3 (saturation) specifications? The amplifier needs to be able to handle the composite power levels expected. The other aspect is the port to port isolation and the actual power level balance at each output port. In other words, a cheap splitter will not provide the same quality and performance as a higher priced, better quality unit.

The fact that the splitter is 75 ohm is somewhat moot. I would only suggest that you use a coax - and proper impedance connectors - of matching impedance. 75 ohm coax of equivalent size will actually have slight less attenuation than a 50 ohm coax. And, a bit of history: Sennheiser RX splitters of 70's and 80's vintage used all 75 ohm CATV parts.

[Lyle Williams]

The legit splitter will be mechanically packaged in a way suitable for the market.  It will also do ancilliary functions like power distribution.

A home-grade TV splitter may be mechanically packaged cheaply.  A good CATV splitter will probably be very durably packaged, but this packaging may not be optomised for audio use.

The amp in a good CATV splitter should be of excellent quality.  It's a huge market, and RF performance matters a lot more than in our audio applications.

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