I'm trying to find some nice flexible coax for my paddle antennas. What do the pros use?
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Best coax for paddles
- Thread starter Silas Pradetto
- Start date
Re: Best coax for paddles
Shure UA825 Extension Cable (25') | Sweetwater.com
Shure Americas | Microphones, Wireless Systems, Headphones, Earphones
I'm not a pro, but I play one on TV. Shure RG8X:
Shure UA825 Extension Cable (25') | Sweetwater.com
Shure Americas | Microphones, Wireless Systems, Headphones, Earphones
What length are you looking for? You can't really decide on a cable without having that in mind. Different cables will have different loses.
About 25 feet. I have the new ua874 paddles with adjustable rf amplifiers.
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Re: Best coax for paddles
Hi Silas,
We'll assume that by "best" you mean lowest loss at UHF frequencies, 50 Ohm impedance, and outer jacket diameters practical for live sound applications and BNC connectors.
In order from lowest loss to highest @ 400MHz:
Times Microwave LMR-400
Belden 9913, 9086, 9096
Wireman 4XL8IIA, FLEXI 4XL
Davis RF Bury-Flex
RG 8, 8A, 10A, 213
Times Microwave LMR-240
RG 8X
RG 58
RG 58A, 58C
Hi Silas,
We'll assume that by "best" you mean lowest loss at UHF frequencies, 50 Ohm impedance, and outer jacket diameters practical for live sound applications and BNC connectors.
In order from lowest loss to highest @ 400MHz:
Times Microwave LMR-400
Belden 9913, 9086, 9096
Wireman 4XL8IIA, FLEXI 4XL
Davis RF Bury-Flex
RG 8, 8A, 10A, 213
Times Microwave LMR-240
RG 8X
RG 58
RG 58A, 58C
Re: Best coax for paddles
I use LMR-400 ultra flex for my antenna cables. LMR240 ultra flex for in rack wiring.
I use LMR-400 ultra flex for my antenna cables. LMR240 ultra flex for in rack wiring.
Re: Best coax for paddles
By 'best' I mean most flexible something like a mic cable - I hate coax curly messes that have to be gaffed down.
I don't think even worst-case losses over 25 feet, especially with 12dB of gain at the antenna, will matter.
By 'best' I mean most flexible something like a mic cable - I hate coax curly messes that have to be gaffed down.
I don't think even worst-case losses over 25 feet, especially with 12dB of gain at the antenna, will matter.
Re: Best coax for paddles
Hi Silas,
Thanks for clarifying your requirements.
At 25ft., any of the UF or F varieties of LMR-400, 9913, LMR-240, or plain RG-8X would work nicely and be reasonably flexible.
The UA874 is an LPDA with an inherent 6dB of gain (over a theoretical isotropic antenna) when the on-board amp is set at 0dB gain. With 25ft. of low-loss cable, the lowest setting of 6dB boost is too much total system gain (12dB) for optimal performance, since it also boosts noise and undesirable signals. It also causes receiver desensitization by slamming the RX front end with signal.
For those not aware, on-board antenna amps should be used only to make up for calculated cable losses and never as an attempt to extend the "over the air" reception range of a system.
Hi Silas,
Thanks for clarifying your requirements.
At 25ft., any of the UF or F varieties of LMR-400, 9913, LMR-240, or plain RG-8X would work nicely and be reasonably flexible.
The UA874 is an LPDA with an inherent 6dB of gain (over a theoretical isotropic antenna) when the on-board amp is set at 0dB gain. With 25ft. of low-loss cable, the lowest setting of 6dB boost is too much total system gain (12dB) for optimal performance, since it also boosts noise and undesirable signals. It also causes receiver desensitization by slamming the RX front end with signal.
For those not aware, on-board antenna amps should be used only to make up for calculated cable losses and never as an attempt to extend the "over the air" reception range of a system.
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Re: Best coax for paddles
Jason, I don't think you looked up the antenna I have. It has four gain settings: -6dB (pad), 0 (pad), +6dB and +12dB. I have been running it at "0" (6dB gain plus 6dB pad) with no issues.
Jason, I don't think you looked up the antenna I have. It has four gain settings: -6dB (pad), 0 (pad), +6dB and +12dB. I have been running it at "0" (6dB gain plus 6dB pad) with no issues.
Re: Best coax for paddles
Hi Silas,
Actually, I know this antenna quite well, but I did look it up before I posted to be sure of my accuracy. However, I should have more clearly written, "the lowest boost setting of +6dB is too much..." I also posted that the LPDA is inherently +6dB while Shure claims +7.5dB for the UA874. Please accept my apology for these oversights.
The schematic printed right on the UA874 amp clearly shows that 0dB is not a pad, but passes signal directly from the LPDA elements. The nomenclature indicates the selected gain/attenuation of the amp/pad device, rather than the total gain of the antenna/amp/pad system.
You will probably have satisfactory performance if you continue to operate the amp as you are now at 0dB. You might even try the -6dB pad if you run into situations where your receivers show overload on the meters.
The issue of excessive gain is more complex than it appears, because efficient antenna designs like LPDA and Helical achieve extra gain on-axis while attenuating signals off-axis. Under certain very specific circumstances, that type of gain can be selective and beneficial. For example, when you know in which direction interference sources are located (which you can sometimes find at TV Fool), you can aim the antenna to get somewhat selective gain within your performance area. Using active wide-band amplification can't be selective because it amplifies all signals, on and off-axis, including noise. Just FYI.
Hi Silas,
Actually, I know this antenna quite well, but I did look it up before I posted to be sure of my accuracy. However, I should have more clearly written, "the lowest boost setting of +6dB is too much..." I also posted that the LPDA is inherently +6dB while Shure claims +7.5dB for the UA874. Please accept my apology for these oversights.
The schematic printed right on the UA874 amp clearly shows that 0dB is not a pad, but passes signal directly from the LPDA elements. The nomenclature indicates the selected gain/attenuation of the amp/pad device, rather than the total gain of the antenna/amp/pad system.
You will probably have satisfactory performance if you continue to operate the amp as you are now at 0dB. You might even try the -6dB pad if you run into situations where your receivers show overload on the meters.
The issue of excessive gain is more complex than it appears, because efficient antenna designs like LPDA and Helical achieve extra gain on-axis while attenuating signals off-axis. Under certain very specific circumstances, that type of gain can be selective and beneficial. For example, when you know in which direction interference sources are located (which you can sometimes find at TV Fool), you can aim the antenna to get somewhat selective gain within your performance area. Using active wide-band amplification can't be selective because it amplifies all signals, on and off-axis, including noise. Just FYI.
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Re: Best coax for paddles
It is usually advantageous to have no active elements in your antenna system if possible. Not only does boost bring up the RF noise floor and potentially desensitize your receivers, active gain stages increase antenna system intermod issues. For a 25 ft run of decent cable (RG8x is nice for this) and an LPDA, IMO no boost is needed.
Just FYI our 25 ft pre-made cables (ARG25) are made of 9913 F7, which has about 3.8 dB of loss at 100 ft @ 700 MHz. Our 15 ft pre-made cables (ARG15) are with RG8X, which exhibits about 11 dB @ 100 ft @ 700 MHz.
Here's a handy reference: Coax Attenuation Chart
-Karl
It is usually advantageous to have no active elements in your antenna system if possible. Not only does boost bring up the RF noise floor and potentially desensitize your receivers, active gain stages increase antenna system intermod issues. For a 25 ft run of decent cable (RG8x is nice for this) and an LPDA, IMO no boost is needed.
Just FYI our 25 ft pre-made cables (ARG25) are made of 9913 F7, which has about 3.8 dB of loss at 100 ft @ 700 MHz. Our 15 ft pre-made cables (ARG15) are with RG8X, which exhibits about 11 dB @ 100 ft @ 700 MHz.
Here's a handy reference: Coax Attenuation Chart
-Karl
Re: Best coax for paddles
Agree. Especially with wideband antennas and amps. If one must use a booster, because of cable/splitter loss, use some kind of filtering before, either a narrowband antenna or a (tunable) bandpass filter.
I like this coax, which is very similar to the Belden: http://ssb.de/pdfs/6080_EcoFlex10_k_en.pdf
Agree. Especially with wideband antennas and amps. If one must use a booster, because of cable/splitter loss, use some kind of filtering before, either a narrowband antenna or a (tunable) bandpass filter.
I like this coax, which is very similar to the Belden: http://ssb.de/pdfs/6080_EcoFlex10_k_en.pdf
Re: Best coax for paddles
+1
Non-amplified LPDA's like the PA805 are superb for RX and TX. I keep a few on-hand because they are so versatile. Generally, when you need to drive long cables, doing the math on your cable loss will allow you to spec a passive LPDA or a Helical, and only resort to amplification when necessary.
+1
Non-amplified LPDA's like the PA805 are superb for RX and TX. I keep a few on-hand because they are so versatile. Generally, when you need to drive long cables, doing the math on your cable loss will allow you to spec a passive LPDA or a Helical, and only resort to amplification when necessary.
Re: Best coax for paddles
[rant] RG58 should be used only for VHF applications, to tie up good coax or wrap around casters to keep racks from rolling. [/rant]
[rant] RG58 should be used only for VHF applications, to tie up good coax or wrap around casters to keep racks from rolling. [/rant]