Geoff Maxwell Posted January 28, 2012 Report Share Posted January 28, 2012 I am getting ready to build a banded antenna cable to use when I move my antenna boom closer to set, rather than run multiple cables. Just wondering what length would be recommended both in practical terms (having enough length for feature work) and functional terms (not losing too much signal) I was thinking 75-100 feet? Using Belden 9258 with powered sharkfins, Lectro Venues and Lectro T-4 IFB. Hoping LarryF can chime in here as well. Thanks... Quote Link to comment Share on other sites More sharing options...
Jeff Wexler Posted January 28, 2012 Report Share Posted January 28, 2012 Larry will probably give a much better answer since you are using Lectro product (powered) antennas (and because he knows a whole lot more about these things than I do), but from previous discussions, 100 feet seems excessive. Since I do not use powered (amplified) antennas, I rarely consider a cable run that exceeds 50 feet. It is quite possible, though I would not know from any personal experience, that a run of 75 to 100 feet is perfectly all right when using an amplified system to deal with loss on the cable run. Quote Link to comment Share on other sites More sharing options...
RPSharman Posted January 28, 2012 Report Share Posted January 28, 2012 The Venue powers antennas through a jumper, requiring opening up the unit. Not convenient. I would examine what the line loss is on your cable and match cable length to the gain of the powered antennas, then leave that cable attached all the time. Run them out as required. I, on the other hand, use short cables with passive antennas and move closer if needed. I will attach 50' cables directly to Venue (so no loss to a barrel) if I have line of sight issues and can't move closer. Robert Quote Link to comment Share on other sites More sharing options...
pvanstry Posted January 28, 2012 Report Share Posted January 28, 2012 Usine belden 9258, you should see around 4-6 db of loss in between 500-700mhz at 100'. I would use an amplifier at the antenna with a gain setting of 6 db to compensate ( I believe you can set at 5 or 8 with the ALP650 antenna, so 5 db would be my choice). Always better to use no amplification as you are amplifying the noise also and get yourself closer to set. Pascal Quote Link to comment Share on other sites More sharing options...
Geoff Maxwell Posted January 28, 2012 Author Report Share Posted January 28, 2012 Thanks guys good advice ... Based on what I am hearing here maybe 50' is a better number, instead of 75'. If I'm already line of sight, does an extra 25 feet of antenna cable buy anything but signal loss if the antennas are aimed properly? I'm also thinking that if I only occasionally needed the 75' vs 50' the unneeded cable would just be laying on the ground sucking up signal. I realize it's all theoretical depending on many factors...but I appreciate hearing your experience. Thanks Quote Link to comment Share on other sites More sharing options...
pvanstry Posted January 28, 2012 Report Share Posted January 28, 2012 I based the loss on 100'. The pros and cons of remoting the antennas depends on so many factor ( reflection, line of sight, absorption etc... ) that it is a question of analizing the situation and applying the best solution. What never fails is reducing the distance in between the transmitter and the receiver. So getting yourself close to set is the best solution. 2nd best is getting the receiver antennas closer. So remoting the antennas are a good thing to have in case it is needed. You might want to think about making a set of 25' and 50' and if you need to have 75' then just join them with an adapter. Pascal Quote Link to comment Share on other sites More sharing options...
Jan McL Posted January 28, 2012 Report Share Posted January 28, 2012 Just chiming in here with my usual response (and personal solution) to being farther away from set than your usual wireless setup will allow: remote the RX and cable back to the cart with cat5e cable. Reasons as follows: antenna cables are difficult to wrangle and unsafe because of their insistence on leaving dangerous upstanding loops and that loss thing...grrr cat5e cables are set friendly and light weight cat5e cable runs can go many hundreds of feet without loss you only need to run one cat5 for 3 RX signals and one send (for ifb); two cat5's get you 7 RX and one send. Going back to watching Hulu and contemplating getting myself a Hat. -- Jan Quote Link to comment Share on other sites More sharing options...
Tyler Faison Posted January 29, 2012 Report Share Posted January 29, 2012 Just chiming in here with my usual response (and personal solution) to being farther away from set than your usual wireless setup will allow: remote the RX and cable back to the cart with cat5e cable. Reasons as follows: antenna cables are difficult to wrangle and unsafe because of their insistence on leaving dangerous upstanding loops and that loss thing...grrr cat5e cables are set friendly and light weight cat5e cable runs can go many hundreds of feet without loss you only need to run one cat5 for 3 RX signals and one send (for ifb); two cat5's get you 7 RX and one send. Going back to watching Hulu and contemplating getting myself a Hat. -- Jan Jan, what kind of interface do you use at the BNC/cat5 exchange? Do you just terminate the cat5 with BNC? Quote Link to comment Share on other sites More sharing options...
Jan McL Posted January 29, 2012 Report Share Posted January 29, 2012 I use the 1/4 wave antennas at the RX (cause it's typically closer to set than the cart EVER is), and use the cat5 to send audio to/from the cart. Baluns at the ends of the cat5e. -- Jan Quote Link to comment Share on other sites More sharing options...
Tyler Faison Posted January 29, 2012 Report Share Posted January 29, 2012 I use the 1/4 wave antennas at the RX (cause it's typically closer to set than the cart EVER is), and use the cat5 to send audio to/from the cart. Baluns at the ends of the cat5e. -- Jan Gotcha. I thought you were saying you used cat5 for your remote antennae, but now I get it. As an audio run for the wireless receiver. Haven't thought to do that, but sounds effective. I personally like seeing my RF (and battery) levels and how it's acting, but I can see how that works in some situations. Quote Link to comment Share on other sites More sharing options...
Geoff Maxwell Posted January 29, 2012 Author Report Share Posted January 29, 2012 Thanks for your suggestion Jan. I used to do that before I got the Venues. And you're right, there's nothing more effective than getting the receivers themselves right around the set very close to the transmitters. I have a little stand with a tripod base and used a BDS system to power everything from NP-1s. But not being as clever as you, I had a 100' set of 7 banded XLR cables, aptly labeled "the cable of death" by my crew. They chipped in and bought me the Venues! ....HA Pascal, I like the idea of 25' and 50' if I don't lose too much signal in the barrels. Larry? Quote Link to comment Share on other sites More sharing options...
jacefivesound Posted January 29, 2012 Report Share Posted January 29, 2012 I, personally, would do 2 sections of 50' 9913 with a coupler in the middle, which is only going to lose you 2-3 db. That way you have 50, and can have 100 for those tough situations. Remember that, as was mentioned here, you have to open up the venue and switch the power on if you need to power your antennas. For 50' runs - 100 ' runs you could probably leave the antennas powered at 3-4 db, but you could also get Lectro's external amplifiers instead if you wanted to switch your power on and off depending on the length of your run, and didn't want to open your venue every time. Here's a coax calculator. Just remember, there's a reason why thick, un-trainable 9913 is typically meant for perminant installs... Coax Calculator http://www.timesmicrowave.com/cgi-bin/calculate.pl Quote Link to comment Share on other sites More sharing options...
RPSharman Posted January 29, 2012 Report Share Posted January 29, 2012 I use plain old 15' RG58 cables over 95% of the time with no reception issues. And I don't like to be close. For line of sight issues I use plain old 50' RG58 cables. I have used those horrible, thick cables working for other mixers in the past and on WB TV shows, and I'm not convinced the performance increase is worth the trouble. Robert Quote Link to comment Share on other sites More sharing options...
jason porter Posted January 29, 2012 Report Share Posted January 29, 2012 I like the idea of remoting the receivers closer to "set" but I like seeing the display. How about an external display of the Rx display to remote back to the cart? Quote Link to comment Share on other sites More sharing options...
ChrisH Posted January 29, 2012 Report Share Posted January 29, 2012 My favortire setup is to have passive antennas built on your cart and hooked up directly to venue with short cables no barrels no loss, then have a boom mast with 100' cable and active antennas. I would set up the bias-ts(to power the amps) on the cart so the 100' cables can be directly plugged to them. When you are inside or dont need the range you just connect venue directly to passive antennas, when you need range or flexibility of the mast, you unplug the passives and route the Venue through the bias-ts to your active antennas. This allows you so much flexibility out side and on location because you can hide and just have your utility dance the mast around with the cameras. When you have a day on a stage you can have your utility leave the mast on the truck and not use it. I think on the last show I was on we used 125' cable and 12 db of gain, we could usually get nearly 500 yards of reliable range with SMVs on 250mW! yay Quote Link to comment Share on other sites More sharing options...
Geoff Maxwell Posted January 29, 2012 Author Report Share Posted January 29, 2012 Thanks Soundguy VERY interesting, but I have a few further questions..perhaps you can take me to school on Bias-ts. So if I understand you correctly, you do NOT use the power from the Venues? Where does the power come from? And where do you tap in the RF signals at the Venues, on the back of the units or a splitter? Sorry I'm trying very hard to understand this configuation. My Venues are not easily accessible neither for RF connections or for power switching. I already have two powered and two passive antennas, so all I need is to understand the patching a bit better. Like you I prefer to be farther away from set...and closer to craft service. Thanks again. Geoff Quote Link to comment Share on other sites More sharing options...
Bartek Posted January 29, 2012 Report Share Posted January 29, 2012 Geoff, That is correct, The venue power stays disabled. the BIAS T's are connected via a jumper to the Venue, and the active antennae are connected to the BIAS T's. All the BIAS T's do is spit out 12VDC to power my antennae amps. When you switch to the passive antennae you simply disconnect the jumpers and stab the passive antennae cable straight into the Venue. The reason for that is if you have the 12V enabled at the Venue and plug in the passive antennae set you essentially short circuit that damn thing... and we all know how that ends. I use the 125 foot system Chris described above, after doing a lot of math and lots of emailing back and forth with Larry, that is the magic number for my system, that is if you want to use the low profile cable, as opposed to the fat cable. the fat cable can increase that length further, but it gets very impractical! I have tested both the cable sourced by Lectro and Trew Audio, both work really well. You can look up a post by Larry of our Email exchange, it explains a lot of the math behind this. Also for all those interested, I did have a bad batch of cable that caused my issues, the manufacturer replaced it free of charge, once we were able to find the problem. if you have any further questions give me a call, or email me... 708.268.5335 Quote Link to comment Share on other sites More sharing options...
LarryF Posted January 30, 2012 Report Share Posted January 30, 2012 At 600 MHz, 100 feet of 9258 has 10 dB of loss. Simply make up that loss with an amplified antenna and you are golden. The amplifier has to go at the antenna or be built in the antenna. You can't effectively amplify after the loss. Here is a coax calculator site for various brands of cable and lengths and frequencies. Loss is very dependent on frequency. http://www.arrg.us/pages/Loss-Calc.htm Best, Larry F Lectro Quote Link to comment Share on other sites More sharing options...
Wandering Ear Posted January 30, 2012 Report Share Posted January 30, 2012 Jan, what kind of stand do you put your recievers on when you move them close to set? Quote Link to comment Share on other sites More sharing options...
RPSharman Posted January 30, 2012 Report Share Posted January 30, 2012 So I'm saying either... A - set Venue jumper at '0' for 12dB of gain at the antenna, and use 100' of flexible Belden 8219 (about 12dB of loss at 600MHz) which can simply stay attached all the time. You don't want 12dB of gain on a short cable. Or B - use 10' of same cable on your antenna mast with passive antennas and move closer as required. Robert Quote Link to comment Share on other sites More sharing options...
pvanstry Posted January 31, 2012 Report Share Posted January 31, 2012 Or... A- Get Times Microwave LMR-240 Ultraflex cable, about the same size as RG-58 but only 6db loss instead of 12db like RG-58. B_ Definitly the way to go!!! Quote Link to comment Share on other sites More sharing options...
RPSharman Posted January 31, 2012 Report Share Posted January 31, 2012 Or... A- Get Times Microwave LMR-240 Ultraflex cable, about the same size as RG-58 but only 6db loss instead of 12db like RG-58. B_ Definitly the way to go!!! Right. There's a setting on the Venue for that loss too, I think. But theoretically the same thing, right? Quote Link to comment Share on other sites More sharing options...
pvanstry Posted January 31, 2012 Report Share Posted January 31, 2012 I will take more original signal vs amplified signal any day. Quote Link to comment Share on other sites More sharing options...
Geoff Maxwell Posted January 31, 2012 Author Report Share Posted January 31, 2012 Thanks Larry for the link, very helpful. Pascal, I'm checking a source for that Ultraflex. Is it as flexible as the name? Does anyone know the loss in a BNC barrel? Quote Link to comment Share on other sites More sharing options...
LarryF Posted January 31, 2012 Report Share Posted January 31, 2012 Connector loss numbers are mistakenly quoted at one decibel per connector and sometimes 0.5 dB. Actually at 600 MHz, with industry standard connectors, the loss is much lower. We always measure less than 0.2 dB per connector with our network analyzers. Unless you have 10 connectors or so in one cable run, I'd simply ignore the connectors in loss calculations. Specifically, two 50 foot cables with a barrel connector is much more job flexible and is more usable for different situations than one 100 foot run. Even four 25 foot lengths and three barrel connectors is quite usable. The only down side is each extra connection is a tiny, possible point of failure though BNC's, if built right, are pretty robust. Best, Larry F Lectro Thanks Larry for the link, very helpful. Pascal, I'm checking a source for that Ultraflex. Is it as flexible as the name? Does anyone know the loss in a BNC barrel? Quote Link to comment Share on other sites More sharing options...
Recommended Posts
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.
Note: Your post will require moderator approval before it will be visible.