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Author Topic: RG-8x vs RG-8 coax  (Read 9275 times)
KC6SLA
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Posts: 35




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« Reply #15 on: November 23, 2013, 09:38:40 AM »

Sounds great. I only run 100 watts so I think I will keep my RG-8x in service. I am in the process of putting up a G5RV and I think I will use the RG-8x I have to feed it.
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W8JX
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« Reply #16 on: November 23, 2013, 03:57:54 PM »

There is only one reason I see to use RG8 over 8X at HF frequencies, power handling capability. 8X is rated at 1kw at 10 MHz and 370w at 50 MHz. From Belden's website.

If running full legal limit use RG8 or equivalent, if less RG8X will work.

No matter what you use buy quality coax from a dealer you trust.

Clif

Strange because no one else rates 8x that way. Its rated 1500 watts at 10mhz and 800 at 50mhz. Even 58 is rated 425 watts at 50 MHz
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KA5IPF
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« Reply #17 on: November 23, 2013, 06:21:12 PM »

There is only one reason I see to use RG8 over 8X at HF frequencies, power handling capability. 8X is rated at 1kw at 10 MHz and 370w at 50 MHz. From Belden's website.

If running full legal limit use RG8 or equivalent, if less RG8X will work.

No matter what you use buy quality coax from a dealer you trust.

Clif

Strange because no one else rates 8x that way. Its rated 1500 watts at 10mhz and 800 at 50mhz. Even 58 is rated 425 watts at 50 MHz


Define "no one else"?

I believe I'll go with Beldens rating since that's all I use.

Clif
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K3DCW
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Posts: 177




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« Reply #18 on: November 24, 2013, 03:24:05 AM »

There is only one reason I see to use RG8 over 8X at HF frequencies, power handling capability. 8X is rated at 1kw at 10 MHz and 370w at 50 MHz. From Belden's website.

If running full legal limit use RG8 or equivalent, if less RG8X will work.

No matter what you use buy quality coax from a dealer you trust.

Clif

Strange because no one else rates 8x that way. Its rated 1500 watts at 10mhz and 800 at 50mhz. Even 58 is rated 425 watts at 50 MHz


Yep, no one else....except the companies that manufacture the cable.

Belden has their ratings.  So does Time Microwave, and they provide an outstanding calculator to figure it all out:

At 10MHz, 85 feet of RG-8X is rated at an average power of 620 watts only.  At 50.125 MHz, that drops to an average of 270 watts.  Note, these are averages, not max power.  What happens if you exceed the ratings?  Well, at the least your cable will get very warm which can cause cable breakdown; at worst it could fail rather dramatically.

Want to check out the figures for yourself a variety of cable types (Times Microwave and non-TM), Times Microwave provides an EXCELLENT calculator.  The info provided includes things like calculated cable loss, assembly loss (cable + connectors), efficiency percentage, and other factors. Here's the link to the measurement for 50.125 MHz.  You can change the parameters (cable type, length or frequency) and it will give you the figures you need/want.

http://timesmicrowave.com/calculator/?productId=121&frequency=50.125&runLength=85&mode=calculate#form

73

Dave
K3DCW
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W8JX
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« Reply #19 on: November 24, 2013, 11:28:11 AM »

Still say those ratings are wrong. I have used over a kw on 40 for many years with 8x and never had a problem or a hot line. If you have high SWR then power eating would be lower.
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NN4RH
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« Reply #20 on: November 24, 2013, 04:15:11 PM »

Kilowatt peak power, or kilowatt average power?

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KA5IPF
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« Reply #21 on: November 24, 2013, 04:40:46 PM »

Still say those ratings are wrong. I have used over a kw on 40 for many years with 8x and never had a problem or a hot line. If you have high SWR then power eating would be lower.

I'm just quoting Belden. Since they build their coax and test it I follow their recommendations.
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K0FOP
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Posts: 4




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« Reply #22 on: December 07, 2013, 09:35:32 AM »

I recently bought some RG8x for an NVIS dipole at Radio Shack ... I had to ream out the PL-259 adaptors
to 0.260 to accommodate this cable.  It is supposed to be 0.242 I believe.  Don't know who makes the cable.
Live and learn ...

Jon K0FOP
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