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Author Topic: 90 degree Coax Connectors Loss Q&A  (Read 658 times)

NT6U

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90 degree Coax Connectors Loss Q&A
« on: December 19, 2021, 03:37:19 PM »

Hello.  I am curious if there is any additional signal loss if using a 90 degree coax elbow VS having a slow gentle sweep in the coax.
Working conditions are.... tower mounted entrance/ service panel.  I can either bend LMR 600 to the Morgan lighting protector or use a 90 degree coax elbow.  Will there be any difference? 10-40 Meters @ +/- 1 Kilowatt.
Does anybody else wonder this? 
Thank you
Greg NT6U
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AA4PB

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Re: 90 degree Coax Connectors Loss Q&A
« Reply #1 on: December 19, 2021, 03:41:22 PM »

I don't think it would make any significant difference on HF - provided that you keep water out of it.
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Bob  AA4PB
Garrisonville, VA

W6QW

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Re: 90 degree Coax Connectors Loss Q&A
« Reply #2 on: December 19, 2021, 04:09:23 PM »

Just a couple of additional observations that you may want to consider:
1.  I highly recommend the use of only the 'genuine' Amphenol right-angle elbow.  Amphenol uses a male/female screw connection at the right-angle point so the center pin connection is reliable.  By contrast, most imported right-angle adaptors use a metal fork-to-pin contact method at the elbow point so there is a possibly of intermittency over time. Given the small price differential, the Amphenol connector is a better bet.
2.  I use a lot of LMR-600 and you will want to note the absolute minimum bend radius specification, if you choose that direction, so that you don't get creepage of the center conductor into the insulating foam over time.
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W6BP

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Re: 90 degree Coax Connectors Loss Q&A
« Reply #3 on: December 19, 2021, 04:23:47 PM »

In the following YouTube video, Jim Heath, W6LG, strings together 55 UHF connectors of various types, including a few that looked like they were used by Marconi, with (by my count) 10 right-angle connectors. He concludes that the total loss at 30 MHz is 0.17dB. You can watch the whole thing, or skip ahead to 3:54 for the results.

https://www.youtube.com/watch?v=PyqJbPdvJak

And I agree that buying a quality right-angle connector, like an Amphenol, is the right way to go.
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K4PIH

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Re: 90 degree Coax Connectors Loss Q&A
« Reply #4 on: December 19, 2021, 04:44:32 PM »

I've cut apart some of the cheap 90's and they use a spring similar to the ones found in cheap click pens. Go Amphenol. My 2cents is for sweeping bend if you can.
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NT6U

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Re: 90 degree Coax Connectors Loss Q&A
« Reply #5 on: December 19, 2021, 05:23:50 PM »

Thank you guys.  That was very helpful !!
Happy Holidays / Merry Christmas
Greg
NT6U
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NT6U

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Re: 90 degree Coax Connectors Loss Q&A
« Reply #6 on: December 19, 2021, 06:03:06 PM »

In the following YouTube video, Jim Heath, W6LG, strings together 55 UHF connectors of various types, including a few that looked like they were used by Marconi, with (by my count) 10 right-angle connectors. He concludes that the total loss at 30 MHz is 0.17dB. You can watch the whole thing, or skip ahead to 3:54 for the results.

https://www.youtube.com/watch?v=PyqJbPdvJak

And I agree that buying a quality right-angle connector, like an Amphenol, is the right way to go.
Informative Video.  Who knew.  Thank you
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SWMAN

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Re: 90 degree Coax Connectors Loss Q&A
« Reply #7 on: December 19, 2021, 07:43:52 PM »

 Old Jimbo had some pretty good info there to share.
« Last Edit: December 19, 2021, 07:47:38 PM by SWMAN »
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WA9AFM

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Re: 90 degree Coax Connectors Loss Q&A
« Reply #8 on: December 19, 2021, 08:48:58 PM »

Ditto on getting Amphenol products.  Yes, the cost more, but they will give great service.
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NT6U

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Re: 90 degree Coax Connectors Loss Q&A
« Reply #9 on: December 19, 2021, 09:26:13 PM »

Ditto on getting Amphenol products.  Yes, the cost more, but they will give great service.
Concur.   When I consider the price of a tower, the grounding, low loss coax, antenna.... It is money well spent IMHO
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N6DXX

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Re: 90 degree Coax Connectors Loss Q&A
« Reply #10 on: December 19, 2021, 11:38:54 PM »

  Lightning does not do well with 90 degree bends, so if the elbow is before the arrestor, I'd go with bending the coax.

   Tony,  N6DXX
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K1KIM

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Re: 90 degree Coax Connectors Loss Q&A
« Reply #11 on: December 20, 2021, 08:23:03 AM »

  Lightning does not do well with 90 degree bends, so if the elbow is before the arrestor, I'd go with bending the coax.

   Tony,  N6DXX

ABSOLUTELY  The larger the radius the better!
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SWMAN

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Re: 90 degree Coax Connectors Loss Q&A
« Reply #12 on: December 20, 2021, 10:11:50 AM »

I have heard that lightning doesn’t like to make left or right hand turns, it only likes to go straight ahead.
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NT6U

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Re: 90 degree Coax Connectors Loss Q&A
« Reply #13 on: December 20, 2021, 02:58:55 PM »

  Lightning does not do well with 90 degree bends, so if the elbow is before the arrestor, I'd go with bending the coax.

   Tony,  N6DXX
"
Interesting.  Taking that thought in theory farther....  "IF" the 90 degree connector is not on the before side of the arrestor, it is on the "after" side of the arrestor would you have additional lightening protection? Hence the lightning doesn't like 90 degree bends.
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K1KIM

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Re: 90 degree Coax Connectors Loss Q&A
« Reply #14 on: December 20, 2021, 03:09:27 PM »


[/quote]"
Interesting.  Taking that thought in theory farther....  "IF" the 90 degree connector is not on the before side of the arrestor, it is on the "after" side of the arrestor would you have additional lightening protection? Hence the lightning doesn't like 90 degree bends.
[/quote]

If lightening makes it past your arrestor and ground rods, you've got more trouble than worrying about a 90 degree bend connector! The ground rods and arrestor are hopefully connected to the earth ground on your electric service panel.
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