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Antenna Cable


Daniel McIntosh
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Just did a bit of Googling... Amphenol bnc connector loss spec is around 0.2 dB and that's at 1+ GHz so it would be a bit less in the UHF spectrum. What about the difference if it is a permanent chassis solder mount or a chassis mount F-F bnc..? Presume the permanent solder option would have less loss as it removes 1 connector from the equation.

Yes I should check in with Larry too, he is the open textbook on this stuff. I'm hoping it's not 3dB as that will probably say goodbye to the patch panel - 1dB I can live with.

Thanks & regards,

Chris.

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...Yes I should check in with Larry too, he is the open textbook on this stuff. I'm hoping it's not 3dB as that will probably say goodbye to the patch panel - 1dB I can live with.

Chris,

Definitely, check with Larry and please correct me if I'm wrong.  I'd hate to misquote him.

FWIW, I don't feel like I'm getting that much loss with my back-of-the-cart connectors.

John B., CAS

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I've always heard that each jumper is a 3db loss, but it's possible I only heard that in my head after many good tequilas.

I don't know what the loss is, but I have always gone straight into the Venue with my 12' cables I use for the antenna mast on my cart.  If I go to the 50' cables, I unplug the short ones and plug in the 50' cables directly, as opposed to barreling it onto the 12' cables.

Robert

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Looking at some of the figures I've found online, I'm wondering if the figure quoted should be more in the neighborhood of .3dB and I simply missed a period.

(I will entertain all jokes that aren't too obvious.)

John B., CAS

Hi John, hopefully that is more in the ballpark! Thanks for mentioning your use of a BNC patch panel also, it is the "real world" use that is always more reliable than the company spec. I imagine quite a few rack based carts must use this system, certainly a lot easier and faster when round the back. I've already have a XLR and power panel and have all the bits to do the BNC one so will play around with it all over the next few weeks after I track down some of that LMR cable.

Regards,

Chris.

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I quite agree Billy

I played around with amps I built in boxes on the aerials and powered down the line.

I got into a real mess in hi RF situations, military airports and close to police HQ's

I threw them all in the bin!!!!

Happy new year

mike

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Not following the logic regarding a 75 ohm "bulkhead" connector - all the Lectro antennas are 50 ohm.

Antenna amplifiers, while useful in some situations, can present a real problem when moving around. As they are typically wideband, they will amplify both wanted and unwanted signals, which can potentially overload the front end RF amplifier in the receiver (although tracking front end's will help significantly in this regard).

Wish the Lectro ALP650 had a way to change the amp gain without fiddling around with jumpers, which would make it much more useful for location work. A switch on the back of the Venue for turning the phantom power on and off would of been nice too....

--Scott

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  • 3 months later...

I'm looking to upgrade some of the cabling I'm using for my antenna, I've been looking at getting some 10-15ft lengths (that's all i need) of the Belden 9913f cable, but then saw the thinner RG-58 stuff which was much cheaper.  I'm starting to wonder that since I'm running only 10 to 15 feet would I really be that much better off with the 9913f cable?

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In a long range walk and talk scene the difference could be one more step or a few more words.  Worth it?

Billy

I'm looking to upgrade some of the cabling I'm using for my antenna, I've been looking at getting some 10-15ft lengths (that's all i need) of the Belden 9913f cable, but then saw the thinner RG-58 stuff which was much cheaper.  I'm starting to wonder that since I'm running only 10 to 15 feet would I really be that much better off with the 9913f cable?

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In a long range walk and talk scene the difference could be one more step or a few more words.  Worth it?

Billy

Turns out that I was able to find the materials to make what I need with the 9913f for the same cost as the RG58 after I posted this lol.  I guess that solves that :P

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For coax lengths less than 15', we recommend and sell an RG58 like cable. At 25' and more we sell the more expensive and bulkier 9913. We will sell the more expensive solution if we think it has value but less than a decibel is below our cost benefit level.

Cheers,

LarryF

I'm looking to upgrade some of the cabling I'm using for my antenna, I've been looking at getting some 10-15ft lengths (that's all i need) of the Belden 9913f cable, but then saw the thinner RG-58 stuff which was much cheaper.  I'm starting to wonder that since I'm running only 10 to 15 feet would I really be that much better off with the 9913f cable?

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  • 11 years later...
On 12/27/2010 at 4:47 PM, RPSharman said:

There is tremendous loss in 100' of antenna cable.  Unless there is a compelling reason (like you only have a Venue and not enough/any portable receivers), then sending out the receivers and running back XLR, as suggested above, it the wise choice.

 

For 50 ohm BNC, I believe I use Belden 5289.  I simply use small zip ties about every 2ft or so to keep my 2 x 50' cables together.  But I rarely use these, and typically only if I am improving line of sight in a tough location by sending them up a stairwell or through a hole in a solid wall or something.

 

Robert

This is an old one but wanted to find out an opinion as I am about to purchase some longer antenna cables. I currently have 15 foot low loss cables just to get high on a stand like a C stand in front of my cart etc. but would like to get 25 or 50 foot cBles made for the same reasons mentioned above. Is 50 foot a common maximum length still getting decent results or should I go with 25 foot to be on the safer side? Was leaning towards the bulkier belden 9913 cable larry mentioned

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Check the link earlier in this thread. It’s a loss calculator on the times-microwave site. You can put in different lengths and different types of cables and see what  loss you’re getting. If you use good RG8X, you can run up to 100 feet without amplification, with LPDA paddles.

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7 minutes ago, Johnny Karlsson said:

Check the link earlier in this thread. It’s a loss calculator on the times-microwave site. You can put in different lengths and different types of cables and see what  loss you’re getting. If you use good RG8X, you can run up to 100 feet without amplification, with LPDA paddles.

Thank you i missed that! Great info. I will check it out

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32 minutes ago, osa said:

Thank you i missed that! Great info. I will check it out

Yeah, it's a pretty good way to get insight into what you're dealing with. It's even slightly different at various frequencies.

Here's the link: https://www.timesmicrowave.com/calculator/

 

BTW - keep in mind that even though the cable loss might be almost -10dB at 100ft, your paddles add roughly +6dB. And getting 100' closer to the Tx will likely more than make up for the ~4dB difference. If your Distro is good, you should be in good shape. Adding an amp may actually over compensate, and as a result overload your receivers - and that would be as the kids say  -no bueno.

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On 8/13/2022 at 3:05 PM, Johnny Karlsson said:

Yeah, it's a pretty good way to get insight into what you're dealing with. It's even slightly different at various frequencies.

Here's the link: https://www.timesmicrowave.com/calculator/

 

BTW - keep in mind that even though the cable loss might be almost -10dB at 100ft, your paddles add roughly +6dB. And getting 100' closer to the Tx will likely more than make up for the ~4dB difference. If your Distro is good, you should be in good shape. Adding an amp may actually over compensate, and as a result overload your receivers - and that would be as the kids say  -no bueno.

I used to be under this impression, but I believe a few years ago, someone at Lectro told me that the inherent gain of the paddles (measured in dBi) is something else and not to be factored into these calculations. Maybe someone could chime in?

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On 12/28/2010 at 3:22 AM, Marc Wielage said:

 

 

snip]  I think this is the Mini8 stuff referred to above. I haven't tried the LMR400 cable, but it's a lot cheaper (half the price). [snip

 

 

On 12/28/2010 at 3:22 AM, Marc Wielage said:

 

--Marc W.

Mini 8 is an improved .250" cable and is only slightly better than RG-58. The larger 9913F is .400" and is much lower loss. (The F suffix is for "Flexible" as the center conductor is stranded. The stranding does lead to slightly more loss than the solid core 9913. Remember the "ironclad" rule of thumb, "If it is smaller, it has higher loss"

Best Regards,

Larry Fisher

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On 8/15/2022 at 8:27 AM, BAB414 said:

I used to be under this impression, but I believe a few years ago, someone at Lectro told me that the inherent gain of the paddles (measured in dBi) is something else and not to be factored into these calculations. Maybe someone could chime in?

If an amplifier is used for gain, both the desired signal + any noise present are both gained up by the amplifier. Some receivers look at the noise level to make diversity decisions and squelch decisions. Excess amplifier gain can upset those systems. There is a place for amplifier gain for such things as balancing out losses in long cables (after the amplifier) or balancing out losses in splitters (after the amplifier). Trying improve performance by wildly amplifying signal and noise is a loser. Introducing loss and then trying to amplify it back up is also too late.

 

Directional antennas have gain for the desired signal with no increase in noise. There is no reason to attenuate this stronger signal as the noise level is low. The stronger signal can overcome cable and splitter losses and still have a good signal to noise ratio at the receiver input. FM and Digital Hybrid systems are immune to desired signal overload. You can have a transmitter right on top of a receiver antenna with no overload. Full digital systems are not quite as bullet proof but good designs have variable gain amplifiers in the RF or IF signal path to overcome the strong transmitter RF signal problem. So in sum, keep RF amplifier gain before all the lossy cables or splitters and within a few dB of the losses. For directional antenna gain with no noise gain, it should never be a problem.

Best Regards,

Larry Fisher

 

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  • 4 weeks later...

Hello, just a late chiming in as I have received my antennas cables from an Italian manufacturer that I did not know about and is not listed in this thread. I still have to test them in the field but already the feel is very good and if they achieve what is on paper then they are close competitors even ahead of Times Microwaves 50ohms cables.

They are called Messi&Paoloni:

https://messi.it/en/catalogue/50-ohm-rf-coaxial-cable.htm

They exist since the 50s. Don't be put off by the slightly tacky graphic design of the website and try their calculator with their different models of cable.

I choose the Hyperflex 5 cause I did not need long length (2.5m) but easy to store and light but not much loss cable. It feels very nice not too hard nor too heavy.

I will edit a report after a testing period on shoot.

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