foliver Posted July 20, 2020 Report Share Posted July 20, 2020 Hello all. I need to buy a bit of coaxial 50 ohm low loss cable for my shark fins. I prefer the soft cables, and light ones..... Someone has a good one to recomend? Thanks a lot! Fabian Quote Link to comment Share on other sites More sharing options...
codyman Posted July 20, 2020 Report Share Posted July 20, 2020 This is a bit random as they aren't really known but I've been having some nice BNC cables made by "American Coaxial Industries" who you can contact and order custom stuff or they have a ton listed on their ebay store (seems they are based on the outskirts of Los Angeles). So far I've had some BNC to BNC timecode cables and a couple of antenna SMA to BNC from them and they seem to be holding up well? Mileage will vary as I haven't put them through the extremes yet considering I only started buying from them a couple months before the pandemic hit but they survived a few weeks in rural Africa on a rather challenging set so so far so good... https://www.ebay.com/str/americancoax1 Quote Link to comment Share on other sites More sharing options...
LarryF Posted July 20, 2020 Report Share Posted July 20, 2020 Just a reminder: Loss per foot is inversely proportional to cable diameter. There is no magic that will give you a low loss, small diameter cable even if the cable is made from unobtainium. Best Regards, Larry Fisher 6 hours ago, foliver said: Hello all. I need to buy a bit of coaxial 50 ohm low loss cable for my shark fins. I prefer the soft cables, and light ones..... Someone has a good one to recomend? Thanks a lot! Fabian 6 hours ago, codyman said: This is a bit random as they aren't really known but I've been having some nice BNC cables made by "American Coaxial Industries" who you can contact and order custom stuff or they have a ton listed on their ebay store (seems they are based on the outskirts of Los Angeles). So far I've had some BNC to BNC timecode cables and a couple of antenna SMA to BNC from them and they seem to be holding up well? Mileage will vary as I haven't put them through the extremes yet considering I only started buying from them a couple months before the pandemic hit but they survived a few weeks in rural Africa on a rather challenging set so so far so good... https://www.ebay.com/str/americancoax1 Quote Link to comment Share on other sites More sharing options...
BAB414 Posted July 20, 2020 Report Share Posted July 20, 2020 I swear by ultraflex: https://fieldcomponents.com/LMR-240-UF-UltraFlex-Cable-Assemblies-Times-Micro.html Make sure you get the 240. Anything higher is stiff and thick. Quote Link to comment Share on other sites More sharing options...
LarryF Posted July 20, 2020 Report Share Posted July 20, 2020 (edited) 11 hours ago, BAB414 said: I swear by ultraflex: https://fieldcomponents.com/LMR-240-UF-UltraFlex-Cable-Assemblies-Times-Micro.html Make sure you get the 240. Anything higher is stiff and thick. Two points: 1. RG-8x is not equivalent to RG-8, a much larger cable with lower loss. 2. The LMR-240 is an improved RG-58 equivalent with 7 dB loss/100 feet. It is not as low loss as RG-8 or Belden 9913F, both 0.400" cables. Best Regards, Larry Fisher Edited July 21, 2020 by LarryF changed feet ' to inches " Quote Link to comment Share on other sites More sharing options...
Derek H Posted July 20, 2020 Report Share Posted July 20, 2020 I would only do LMR-240-UF for short runs. Like 15’ up the antenna mast. RG8x is the same stuff minus the foil shield so it’s more flexible and lays more flat. Better for long runs where you’re amplifying at the antenna. Belden 9258 Quote Link to comment Share on other sites More sharing options...
BAB414 Posted July 20, 2020 Report Share Posted July 20, 2020 58 minutes ago, Derek H said: I would only do LMR-240-UF for short runs. Like 15’ up the antenna mast. RG8x is the same stuff minus the foil shield so it’s more flexible and lays more flat. Better for long runs where you’re amplifying at the antenna. Belden 9258 Just speaking from personal experience... The ultra flex is...ultra flexible (the 240 version!). And I regularly do 100' runs on it with powered fins and it's never let me down. Quote Link to comment Share on other sites More sharing options...
Derek H Posted July 20, 2020 Report Share Posted July 20, 2020 Are you talking about the times microwave brand stuff? If so, the stuff I got, ordered from DX engineering, was a noticeable amount stiffer than Belden 9258. (RG8x) You could certainly use it for long runs but I found that sticking with RG8x was my preference. The LMR240UF definitely seems like a much better shielded cable than RG8x. I also chose to use the ultraflex for short jumpers inside my cart where god knows what kind of EM is flying around. The other nice thing about Ultra Flex and Belden 9258 is you can use the same model Amphenol BNC on either one. Quote Link to comment Share on other sites More sharing options...
BAB414 Posted July 20, 2020 Report Share Posted July 20, 2020 40 minutes ago, Derek H said: Are you talking about the times microwave brand stuff? If so, the stuff I got, ordered from DX engineering, was a noticeable amount stiffer than Belden 9258. (RG8x) You could certainly use it for long runs but I found that sticking with RG8x was my preference. The LMR240UF definitely seems like a much better shielded cable than RG8x. I also chose to use the ultraflex for short jumpers inside my cart where god knows what kind of EM is flying around. The other nice thing about Ultra Flex and Belden 9258 is you can use the same model Amphenol BNC on either one. I am. All I know is, it works. It's something I was looking for for a long time. Lot's of people these days are talking about remoting their receivers because of social distancing on set, etc and they're going all dante and cat5/6. I've lived that life as well but ultraflex makes remoting antennas over long distances a breeze, especially with the newer powered antennas. Less gear I have to worry about being too far away from me, direct control and sight of my receivers, and same (or very similar) results. Quote Link to comment Share on other sites More sharing options...
foliver Posted July 21, 2020 Author Report Share Posted July 21, 2020 Thanks all for your replies, and information! BAB414, what shark fins are you using? How many feet run you can do without using powered antennas?, i know it's a difficult question, but ... Thanks again!! Quote Link to comment Share on other sites More sharing options...
BAB414 Posted July 21, 2020 Report Share Posted July 21, 2020 My new setup is 10 feet of ultraflex 240 with ALP620 passive fins (just switched over from 15 feet of RG-8x - not for increased performance, I just wanted shorter custom cables so I figured I'd go with them). If I need to get them around a corner, I've been switching to 25 feet of RG-8x (that's just what I have). Anything more, I switch to my Shure UA874 active fins with the 100ft ultraflex with the antennas at +6 gain. Been doing it like this for a 2-3 years with antennas going straight into the Venue 2. I just added the aforementioned 10 ft ultraflex installation for the cart and a small patch bay with 2 feet of cable between it and the Venue for quicker antenna switching. What's also cool is that the ALP620's are passive but sending them power doesn't do any harm, so I can just leave the power setting on in the Venue so that's one less step to worry about. I haven't tested the limits of passive fins with ultraflex but I calculate about 6dB of loss over 100ft (Larry says 7 so I'd go with that figure). Lectro and Wisy have some very cool looking antennas where you can dial in exactly how much gain you want and attenuate. I think these are ideal. Especially having two sets so you can quickly switch over without dismantling your cart. Something to be aware of for any cable, especially skinny ones, if they get scissored in a door, you're gonna have a bad time. Quote Link to comment Share on other sites More sharing options...
LarryF Posted July 21, 2020 Report Share Posted July 21, 2020 1 hour ago, BAB414 said: [snip] I haven't tested the limits of passive fins with ultraflex but I calculate about 6dB of loss over 100ft (Larry says 7 so I'd go with that figure). [snip] The 7 dB number is for the upper frequency end (600 MHz+) of U.S. frequencies. If you are at the lower end (500 MHz) 6 dB is correct. Best, LEF Quote Link to comment Share on other sites More sharing options...
BAB414 Posted July 21, 2020 Report Share Posted July 21, 2020 After talking to Karl W, I'm considering getting 3dB passive gain attenuators because I'm worried I'm coming in too close to 0, but other than the normal NYC problems I'm used to (crowded spectrum etc), I've had great performance. Quote Link to comment Share on other sites More sharing options...
LarryF Posted July 21, 2020 Report Share Posted July 21, 2020 2 hours ago, BAB414 said: After talking to Karl W, I'm considering getting 3dB passive gain attenuators because I'm worried I'm coming in too close to 0, but other than the normal NYC problems I'm used to (crowded spectrum etc), I've had great performance. What problem are you trying to solve with 3 dB attenuators? LEF Quote Link to comment Share on other sites More sharing options...
BAB414 Posted July 21, 2020 Report Share Posted July 21, 2020 42 minutes ago, LarryF said: What problem are you trying to solve with 3 dB attenuators? LEF The theoretical problem of overloading the receiver with RF. I haven't had any issues, but Karl's video Best RF Practices opened my eyes to correctly dealing with signal loss and compensating with gain. My understanding is that sharkfin antennas (active or passive) natively have 4 dB of gain. If I run 100 feet of LMR240-UF, I lose about 6dB, which means the RF signal hits the receiver at -2dB (if I don't add/subtract any gain from the antenna). I'm under the impression that -6 - -2 dB is the sweet spot because you don't want to overload. Would love to hear your thoughts. Quote Link to comment Share on other sites More sharing options...
LarryF Posted July 22, 2020 Report Share Posted July 22, 2020 Let me clarify some points. Gain from a directional antenna is different from the gain of an amplifier. An amplifier gains up both the desired signal, in band but undesired RF signals, and any undesired noise. Too much of this amplifier gain can upset the squelch circuits, diversity system, sliding filters (Lectro) and other parts of the receiver system. By too much gain, we are speaking of more than say a total 6 dB of amplifier gain after cable losses. Since off frequency signals may also be gained up by the amplifier, intermod can also increase. Antenna gain is a horse of different feathers. Antenna gain is directional gain and is largely noiseless in the sense that the desired signal may increase but undesired signals (noise floor) are largely rejected by the amount of gain of the antenna and background noise is reduced too, i.e., an antenna with 4 dB of directional gain increases the desired signal by 4 dB but the noise floor does not increase. If an interfering signal is in the null of an antenna, you would get even more rejection. In sum, don't attenuate the gain (directional antenna gain) of a passive antenna. Do attenuate amplifiers for active antennas at the receiver end of your cabling if you have excess gain of say 5 dB or more. Excess gain is the amplifier gain minus cable losses and splitter losses. Finally, it is hard to overload the inputs of modern receivers with a desired signal due to robust front ends and AGC (Automatic Gain Control) in digital receivers. However, gaining up the noise floor can cause problems as discussed above. The final comment => You don't need a 3 dB attenuator. Best Regards, Larry Fisher Quote Link to comment Share on other sites More sharing options...
drpro Posted July 22, 2020 Report Share Posted July 22, 2020 LDF-5 1db loss per hundred feet at 600MHz. Great for fixed installations, but a bear on location!! Quote Link to comment Share on other sites More sharing options...
BAB414 Posted July 23, 2020 Report Share Posted July 23, 2020 15 hours ago, LarryF said: Let me clarify some points. Gain from a directional antenna is different from the gain of an amplifier. An amplifier gains up both the desired signal, in band but undesired RF signals, and any undesired noise. Too much of this amplifier gain can upset the squelch circuits, diversity system, sliding filters (Lectro) and other parts of the receiver system. By too much gain, we are speaking of more than say a total 6 dB of amplifier gain after cable losses. Since off frequency signals may also be gained up by the amplifier, intermod can also increase. Antenna gain is a horse of different feathers. Antenna gain is directional gain and is largely noiseless in the sense that the desired signal may increase but undesired signals (noise floor) are largely rejected by the amount of gain of the antenna and background noise is reduced too, i.e., an antenna with 4 dB of directional gain increases the desired signal by 4 dB but the noise floor does not increase. If an interfering signal is in the null of an antenna, you would get even more rejection. In sum, don't attenuate the gain (directional antenna gain) of a passive antenna. Do attenuate amplifiers for active antennas at the receiver end of your cabling if you have excess gain of say 5 dB or more. Excess gain is the amplifier gain minus cable losses and splitter losses. Finally, it is hard to overload the inputs of modern receivers with a desired signal due to robust front ends and AGC (Automatic Gain Control) in digital receivers. However, gaining up the noise floor can cause problems as discussed above. The final comment => You don't need a 3 dB attenuator. Best Regards, Larry Fisher Thanks Larry. This is helpful and actually makes sense. I didn't think I needed attenuators but wanted to experiment because my (flawed) math wasn't in line with my real world experience (which has been good!). I thought all RF "gain" was the same. Had no idea. There's no way I'm ever coming close to +5dB so I'm going to keep truckin' as I have been! Really appreciate what you and Karl have taught me. Love Lectro! Quote Link to comment Share on other sites More sharing options...
danelonsdale Posted July 25, 2020 Report Share Posted July 25, 2020 Belden 9258. It’s an RG-8X. Coils very nicely, feels like a 75ohm video bnc and has reasonable loss. I carry two that are 115’ each which is 10.5db loss at 500mhz and 11.5db at 600mhz. Seems to be a perfect length for remote fins. The short cables with passive fins don’t really matter as much. I’ve used the cables with Lectro ALP650 and Wisycom LFA shark fins. Seems great with both. Gotham built the cables for me. also: https://www.qsl.net/co8tw/Coax_Calculator.htm Quote Link to comment Share on other sites More sharing options...
foliver Posted August 3, 2020 Author Report Share Posted August 3, 2020 Thanks Larry and all for the contribution to this thread, i've learned a lot ! Fabian Quote Link to comment Share on other sites More sharing options...
Shastapete Posted August 3, 2020 Report Share Posted August 3, 2020 11 hours ago, foliver said: Thanks Larry and all for the contribution to this thread, i've learned a lot ! Fabian I think it's time for Larry to write his memoir/technical reference "Tumbleweeds and Transmitters" Quote Link to comment Share on other sites More sharing options...
lyrnxG Posted March 24, 2021 Report Share Posted March 24, 2021 I took advice from this thread and went with ultraflex 240. Made the mistake of ordering the 50ohm connector below. The ultraflex would not fit. May I ask what connectors you guys are using for thicker gauge cables? Thank you Quote Link to comment Share on other sites More sharing options...
nevo Posted March 24, 2021 Report Share Posted March 24, 2021 I got the amphenol ones Quote Link to comment Share on other sites More sharing options...
BAB414 Posted March 24, 2021 Report Share Posted March 24, 2021 1 hour ago, lyrnxG said: I took advice from this thread and went with ultraflex 240. Made the mistake of ordering the 50ohm connector below. The ultraflex would not fit. May I ask what connectors you guys are using for thicker gauge cables? Thank you When I ordered the ultraflex from Field Components, I had them build the whole cable for me. Not sure what connectors they use but haven't had problems with them. Quote Link to comment Share on other sites More sharing options...
Derek H Posted March 24, 2021 Report Share Posted March 24, 2021 What’s the model number of that BNC? They all look like that... i think the one you want is 112533 but I’m going off memory there. Quote Link to comment Share on other sites More sharing options...
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