Help on choosing Antenna combiner for cart

[jonathan chiles]

I've been looking over past discussions on the topic of antennas and active and passive combiners but still feel a bit in the dark and am hoping for some more discussion.

What I am looking at for the cart I am building is a stand alone unit that will distribute 2 Dipoles or LPDAs to 4-6 Lectro 411's

I often need to take receivers out for bag work so am looking at these 4 options:

A) 2 x PSC RF Multis (1 per Antenna)

Lectro UMC16BL Rack mount ADA

C) Audio Technica half rack unit ATW-DA49

http://www.audio-technica.com/cms/accessories/b2f1e766e2abec42/index.html

D) 2 x Mini Circuit 4 way passive splitters

I am quite intrigued by the Audio Technica unit, they seem to go for around $400 but am not sure if the Lectro equivalent UMC16B is better or not, hoping some users can comment!

[studiomprd]

Audio Technica is an established player in the worldwide wireless microphone field (primarily Entertainment/Live Sound, with a lot of major endorsing performers, big shows, and very happy customers. They are not a big player in the Production Sound for TV-Movies, but they have quality products, and stand behind them from Stow OH.

As always, the rule is: Generally speaking, you get what you pay for.

Edited June 27, 2011 by studiomprd

[LarryF]

Hi Johnathan,

I'd feel better about the AT's if they gave some performance specs. Distribution amps lead a hard life since users have pretty well made the manufacturers go to wideband units. This means the distribution amp will see every RF signal between DC and light (440 MHz to 900Mhz for the AT, 450 MHz to 900 MHz for the PSC), including any 50kW TV stations that are in the locality. Because of this, you'd like to have a distribution amp with a tough RF amplifier as well as low self noise. Neither AT or PSC specifies 3rd order intercept which is the universal measure of overload and/or intermod resistance. They may be great but without specs how can you tell? They do have the distinct advantage of being more "reasonable" in price. Also, both the AT and PSC units are made for all markets rather than the U.S. market which currently is 470 MHz to 700 MHz. Letting the upper end go out to 900 MHz is not wise, IMHO, because of more and more garbage in the 700 to 900 MHz area.

Obviously, I am biased here, but partly because I know what goes into the Lectro units. A lower cost suggestion would be to use one of the other two units units and put one of our passive filters (PF25 or PF50) in the antenna line before the distribution amp antenna input. That will cut down tremendously on the unwanted RF going into these units. That will restrict your operation to one (PF25) block or two (PF50) blocks. You can select different filters if you move around and match the filters to the blocks you will be using. That isn't a bad idea also for our distribution amps if you can stand 25 or 50 MHz of operating bandwidth.

The Mini-Circuits passive splitter won't have any overload or intermod problems but you will have 6 dB of overall loss. If the talent is relatively close to the antennas, this is workable. It is equivalent to cutting the transmitter power by four or doubling the antenna to transmitter distance. It is a solid low cost alternative with the provisos above. In really noisy urban environments, this loss may not even be noticeable since the loss affects both the signal and the noise.

If this has created more questions than answers, ask on.

Best,

LarryF

Lectro

I've been looking over past discussions on the topic of antennas and active and passive combiners but still feel a bit in the dark and am hoping for some more discussion.

What I am looking at for the cart I am building is a stand alone unit that will distribute 2 Dipoles or LPDAs to 4-6 Lectro 411's

I often need to take receivers out for bag work so am looking at these 4 options:

A) 2 x PSC RF Multis (1 per Antenna)

Lectro UMC16BL Rack mount ADA

C) Audio Technica half rack unit ATW-DA49

http://www.audio-tec...ec42/index.html

D) 2 x Mini Circuit 4 way passive splitters

I am quite intrigued by the Audio Technica unit, they seem to go for around $400 but am not sure if the Lectro equivalent UMC16B is better or not, hoping some users can comment!

[Zack]

I have been using the Mini-circuits 4-way passives for a while now with great success. They are used only with my cart really, but were easy to adapt anywhere on the cart from their small size. I have them feeding x2 411's and an SRa. If I knew about AT's multi-coupler at the time, I might have gone with that instead, being that it says it includes cables as well. I've heard some bad reviews from those that have used the smaller PSC Multi boxes, however their Multi-Dual is excellent. Given that you're wanting to feed up to 8 receivers, I think you'll be better off getting like a PSC Multi-Dual, or the Lectro UMC16B, using a passive splitter with more than 4 outs seems to be too great of a loss.

[jonathan chiles]

Thanks for the replies gentlemen:)

Larry I was hoping you would throw in a word or two. I did feel like specs were on the vague side with the AT and PSC RF Multi units and I did download the UMC16B manual and noted the 3rd order intercept etc

Seeing as I will be operating 4 UCR411s on my cart for now but later would like to expand to 6 and more it does seem wise to go with a unit that can grow with my cart so to speak.

So I will probably go with the UMC16B. I am operating on block 22 and 24 is there a filter that can operate from 563 - 638Mhz or can that pass band be custom ordered built in to that unit?

Also regarding antennas, I have read that 1 dipole and 1 LPDA can work well with a diversity system. Any discussion on antenna types would be interesting

[LarryF]

Hi Johnathin,

We don't have a 75 MHz filter. As filters get wider, the out of band rejection gets worse anyway. Split blocks is a good reason for a strong distribution amp. If you are going to 6 channels, then the extra outputs of the UM16B makes sense. You don't need to terminate unused outputs, by the way.

My recommendation is to use two similar antennas. The SNA dipole will stretch to cover 22 and 24. Simply set them for block 23. They are compact and easy to mount up in the air where you can get excellent range.The LPDA has sligthly more gain (+4 dB) than the dipole with more back rejection, but not as portable. They also cost more bucks. There are some other sharkfin LPDAs on the market and while they may not be as brute strength rugged, are still strong, good performers and very good buys. The ventilated units are better outside if wind is a factor.

There is nothing wrong with first buying the dipoles. The price is good and e,ven if you end up with LPDAs or other directional antenna at some point, the dipoles are still a handy part of your kit.

Best,

LarryF

Lectro

Thanks for the replies gentlemen:)

Larry I was hoping you would throw in a word or two. I did feel like specs were on the vague side with the AT and PSC RF Multi units and I did download the UMC16B manual and noted the 3rd order intercept etc

Seeing as I will be operating 4 UCR411s on my cart for now but later would like to expand to 6 and more it does seem wise to go with a unit that can grow with my cart so to speak.

So I will probably go with the UMC16B. I am operating on block 22 and 24 is there a filter that can operate from 563 - 638Mhz or can that pass band be custom ordered built in to that unit?

Also regarding antennas, I have read that 1 dipole and 1 LPDA can work well with a diversity system. Any discussion on antenna types would be interesting

[Izen Ears]

I must chime in here and say when I got my initial high-gain antennas I went with the PSC multi-dual with the PSC sharkfins. (The UMC16BL was not to be available for a few years.) Then I got PW helicals and boy what an improvement in performance, but I would still see some "noise" (little blips in the RF spectrum display on the 411s) when I turned on the Comtek BST-216, and also the Lectro T4, which was two full blocks away from any of the 411s.

Then I decided to get back ups of everything, and instead of another PSC multi-dual I went with the Lectro UMC16BL for my eight 411s. I am so happy I did. I saw a dramatic increase in signal strength / range and zero noise when I turn on other wireless devices (or put their antennas) right in front of the helicals. I run them up to 100' (only on RG8 cable of course) when I have to, but usually they live on the cart on 15' RG8 cables. But I will still keep the PSC Multi_Dual as a back up; after all I had several successful years with it.

Dan Izen

[jonathan chiles]

Thanks guys, great info here.. valuable to me and hopefully others who swing by here in the future:)

JC

[cjh]

I've been looking over past discussions on the topic of antennas and active and passive combiners but still feel a bit in the dark and am hoping for some more discussion.

What I am looking at for the cart I am building is a stand alone unit that will distribute 2 Dipoles or LPDAs to 4-6 Lectro 411's

I often need to take receivers out for bag work so am looking at these 4 options:

A) 2 x PSC RF Multis (1 per Antenna)

Lectro UMC16BL Rack mount ADA

C) Audio Technica half rack unit ATW-DA49

http://www.audio-technica.com/cms/accessories/b2f1e766e2abec42/index.html

D) 2 x Mini Circuit 4 way passive splitters

I am quite intrigued by the Audio Technica unit, they seem to go for around $400 but am not sure if the Lectro equivalent UMC16B is better or not, hoping some users can comment!

I recently redid my whole antenna set up and got the shure equivalent of the above audio tech unit, I got the whole kit including 2 x active sharkfins from BH Photo for about $1000. In practice the rig works very well and I would happily recommend it, I currently use it to feed 2 x Zaxcom QRX's and a Lectro venue. The only bad thing I'd say is the shure sharkfin antenna are quite flimsy and thin, they have a high wind rating but I'm yet to test that as to date all their use has been studio based.

Through a bit of a communication error I did end up importing 2 complete systems so have one for sale if anyone local (NZ or Aussie) is reading, if you're in the US got to BH, they have the best price.

Regards,

Chris.

[RPSharman]

A bit of a resurrection.

Wondering if there's much of a difference between the mini-circuits ZN4PD-272+

Or the ZFSC-4-1+

I like the form factor of the first one better, and specs seem about the same.

This is for use in a bag in a process trailer or near enough talent that 6dB loss is not my concern.

[Conor998]

Hi,

Has anyone else got anymore feedback on the Shure UA844SWB ??

Its seems to have a 3rd order interception point also.

Could be another option.