Small RF distro

[samchurchill]

Hi, I have two Sennheiser ew100 G3 receivers in a small rack that have previously just been using their own small antennas, but we’re now investing in some external paddle antennas.

 

Unfortunately there isn’t space in the rack for 1U of RF distro, and changing the rack would be tricky for several reasons, so I’m looking for a small solution that can fit in there.

 

I’ve come across the Sennheiser ASP 212 but it seems extremely expensive for what it is - does anyone know of any cheaper alternatives, even if it would be 2 splitters instead of 1?

 

Also, do you think I’m likely to regret going for a passive splitter? As it’s only going to 2 receivers I thought I could get away with it without too much loss of gain.

 

Thanks,

 

Sam

[mackerr]

Hi, I have two Sennheiser ew100 G3 receivers in a small rack that have previously just been using their own small antennas, but we’re now investing in some external paddle antennas.

 

Unfortunately there isn’t space in the rack for 1U of RF distro, and changing the rack would be tricky for several reasons, so I’m looking for a small solution that can fit in there.

 

I’ve come across the Sennheiser ASP 212 but it seems extremely expensive for what it is - does anyone know of any cheaper alternatives, even if it would be 2 splitters instead of 1?

 

Also, do you think I’m likely to regret going for a passive splitter? As it’s only going to 2 receivers I thought I could get away with it without too much loss of gain.

 

Thanks,

 

Sam

 

You would be fine with 2 passive splitters as long as you will only need to feed 2 diversity receivers. A passive splitter is not a BNC T connector. You want an actual RF splitter that covers the frequency range you use.

You will also experience 3dB of loss through a 2 way passive splitter, plus maybe a half dB of insertion loss.

 

A good choice can be found from Minicircuits, like THIS ONE. These will require short SMA-BNC adapter cables as they come with SMA connectors on them.

 

Mac

Edited May 31, 2019 by mackerr

[Stuart91]

These will require short SMA-BNC adapter cables as they come with SMA connectors on them.

 

What sort of signal loss are these adaptors likely to add?

 

(I've always tried to avoid them, but based on hunch rather than concrete knowledge)

[paulears]

Passive splitters like the ones linked to are fine - I've got a rack with the usual branded splitters and the other with two 4 way passive splits - wide band types with similar loss specs, and they're just as solid. I've always said that radio mic issues are caused by those RF black holes, where the path vanishes totally, rather than a few dB of loss - which we get in remote antennas anyway. SMA connectors really mean sourcing ready made ones, as they are a bugger to solder reliably without a tiny iron and a magnifying glass, and I still mess them up.

[samchurchill]

Thanks all. I've just spoken to Mini-Circuit's UK office in Surrey and they suggested https://www.minicircuits.com/WebStore/dashboard.html?model=ZAPD-1%2B - a bit more expensive than the SMA version (although still less than Senny ASP212) but has a more appropriate bandwidth filter and uses BNC, so no need for SMA cables. Any thoughts on why this wouldn't be appropriate? Thanks again.

[sandall]

As Mac suggests, passive splitters should be fine, but you can do the job for a tiny fraction of the cost by using ordinary TV aerial splitters. Buy a couple of low-loss splitters & a few short TV aerial links, cut the links in half & solder BNCs to the cut ends. Or cut some BNC leads in half & solder coax connectors onto them. Then take a weekend-break with the money you've saved.

 

When I was doing kids' shows I made up a couple of 4-channel racks (one VHF, the other UHF), each with a pair of 4-way wide-band TV & radio aerial amps in them. Both used standard Trantec aerials dangling in mid-air, though I did later treat the UHF one to a couple of el-cheapo 3-element Yagis. I should really have added a bit of filtering, but both worked fine without.

[samchurchill]

Thanks, are you talking https://cpc.farnell.com/antiference/a1400r/4way-signal-booster-amplifier/dp/AP00783?mckv=sfxCYmIjQ_dm|pcrid|224680055011|kword||match||plid||slid||product|AP00783|pgrid|51011277550|ptaid|pla-427213548916|&CMP=KNC-GUK-CPC-SHOPPING&gclid=Cj0KCQjwocPnBRDFARIsAJJcf94KDbNuhGZQs52bJiKID7k65Lgfo73aisVj5P-w0frSpcYtxFngQTQaAl5aEALw_wcB or https://www.screwfix.com/p/4-way-splitter-with-powerpass-all-ports/69265?tc=AB5&ds_kid=92700024372740822&gclsrc=aw.ds&ds_rl=1241687&ds_rl=1245250&ds_rl=1249401&gclid=Cj0KCQjwocPnBRDFARIsAJJcf976TwGrDzh2c113pqEy9grSFewxW4lf-HHiXKDboAWJvM_NdDiIKn0aAixxEALw_wcB?

[sandall]

Thanks, are you talking https://cpc.farnell....TQaAl5aEALw_wcB or https://www.screwfix...0aAixxEALw_wcB?

I'm a bit surprised that Screwfix only seem to do ones with F connectors, but unless you are a fan of these I would stick to bog-standard Belling connectors. The CPC price seems a bit high, so it might be worth checking B&Q, Wickes or Argos.

[sunray]

I knocked up an ADU in a hurry when a rack in a hall had to be moved maybe 10 years ago. As I had 8way TV splitters & mains powered TV amps in a box from a rip out they got dumped in the bottom of the rack as a temporary get out of jail.

It remained in regular use until last year when both amps had failed (presumably at different times).

By then they had been running for around 40 years.

The repair, which I haven't seen, is Trantec pre-amps.

 

I recently needed some ch70 yagis in a hurry, the only full range things my local TV trade supplier listed are some small log periodics about 250mm long which have proved to be good enough.

Edited May 31, 2019 by sunray

[david.elsbury]

Not an RF expert but I’d avoid Belling-Lee connectors. they can be super loose fitting and I imagine there’s a lot of potential signal loss there. Would be much happier with compression type F connectors.

[samchurchill]

How about https://cpc.farnell.com/labgear/fju402/splitter-2-way-uhf-5-1000mhz/dp/AP02104 - looks like it’d work nicely, and haven’t spent much of for any reason it doesn’t.

 

Although it is 75ohm - I’d normally go for 50ohm, but not sure if that’s important!

Edited June 1, 2019 by samchurchill

[sandall]

Even taking into account David's comments on Belling-type plugs, some of are indeed pretty awful, what I would generally use for aerial splitting is RS 749-2490 https://uk.rs-online...ed%22%3Atrue%7D with decent metal, not plastic connectors. Over the short distances involved I don't think the difference between 50 & 75 ohms is going to be very significant (I assume G3s are 50 ohm; the G2 manual doesn't say, but G1s & XSWs are).

 

 

 

 

 

Edited June 1, 2019 by sandall

[david.elsbury]

The difference between 50 and 75 ohms is completely irrelevant here. Using 75R hardware and good quality low loss coax is fine

 

http://audiosystemsgroup.com/Which_Coax_for_Wireless_Mics.pdf

[Simon Lewis]

I've followed this thread with interest, as I'm presently repackaging a set of older Sennhesier G2 units in preference to spending £££ on new G4s.

It seems that low cost antenna distribution solutions are possible, but I wondered if anyone has had a chance to try out the Thomann antenna splitter unit? Some parts look a little cheap, but it does at least offer a rack mount unit for a fairly low price...?

 

[paulears]

I've ordered a similar product from China with a couple of log periodic antennas. I'll let you know how well it solves my problem when it arrives.the Chinese suppliers have a few very similar products I note.