| Author |
Message |
    
Charliebrown
Intermediate Member
Username: Charliebrown
Post Number: 156
Registered: 10-2002
| | Posted on Monday, March 14, 2011 - 8:13 am: | 
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TECH 833. I am getting rid of my 3/4 inch 75 ohm solid aluminum shield cable due to the damage over the year's and too many splice's. It is App. 500 foot to my antenna up a mountain. I am thinking of getting the CA 400 coax to replace it. So, do you think that the CA 400 will be better or worse on VELOCITY, ATTENUATION over the hard line? I have the spec's on the CA 400 but not the hard line. I do not know the manufacture of the hard line. |
Tech833
Moderator
Username: Tech833
Post Number: 1928
Registered: 8-2002
| | Posted on Monday, March 14, 2011 - 12:46 pm: |
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Hi CB,
3/4 inch 75 ohm cable in hard line? I Have never heard of that. Perhaps you meant heliax?
Hard line comes in 10 or 20 foot sections with flanges on both ends and is bolted together with nuts and bolts. The center conductors are joined with appropriate sized bullets. Heliax is a semi-rigid coaxial cable with a jacket that can be rolled up.
Anyway, assuming you meant heliax, I can compare numbers for you.
50 ohm 1/2 inch heliax (outer diameter closer to 3/4 inch) has an average attenuation per 100 feet at 30 MHz. of 0.35 dB. Add additional losses for the 50 to 75 ohm differential, and you are looking at around 0.42 dB per 100 feet at 30 MHz.
LMR-400 (closest thing to CA 400 that I have info for) shows attenuation per 100 feet at 30 MHz. of 0.422 dB. That is a difference of only 0.002 dB. For a 500 foot run, that would be 0.01 dB difference. That is almost unmeasurable in the field.
Go with the CA 400 cable and fear not about losses.
Your radio 'Mythbuster' since 1998
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Charliebrown
Intermediate Member
Username: Charliebrown
Post Number: 157
Registered: 10-2002
| | Posted on Monday, March 14, 2011 - 1:06 pm: |
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tECH 833, I THINK THE NUMBER FOR THIS CABLE IS THE 750 , P3 JCAM MESSENGER CABLE IF I HAD BEEN TOLD CORRECTLY. AGAIN I AM IN THE DARK ABOUT THIS CABLE BUT, IT IS WHAT OUR LOCAL TV COMPANY USE TO USE FOR THEIR MAIN LINE CABLE. I THANK YOU 833 FOR YOUR QUICK RESPONSE AND PATIENCE OF ME NOT HAVING MORE INFO ON THIS BUT THAT IS ALL I HAVE SO FAR TO GO ON. I HOPE THIS WILL HELP YOU TO HELP ME ON THIS SUBJECT. ONCE AGAIN THANKS |
Tech833
Moderator
Username: Tech833
Post Number: 1930
Registered: 8-2002
| | Posted on Tuesday, March 15, 2011 - 12:37 pm: |
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We are all here to help, CB. It would be helpful if you provide readers and members here with a report after you install the CA 400 cable.
Thank you in advance.
Your radio 'Mythbuster' since 1998
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Charliebrown
Intermediate Member
Username: Charliebrown
Post Number: 158
Registered: 10-2002
| | Posted on Tuesday, March 15, 2011 - 2:01 pm: |
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TECH 833, that is the least I could do since we are here to help each other learn to improve and enjoy the hobby we are in. No matter if it is police scanner's , short wave , ham , or cb radio. Once again 833 thank you and other's for the great vast of information that is given. I am waiting for the weather to improve before I take on this task. It's been too cold and wet. |
Charliebrown
Intermediate Member
Username: Charliebrown
Post Number: 159
Registered: 10-2002
| | Posted on Wednesday, March 16, 2011 - 7:28 am: |
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TECH 833, Copper electronic's gave information on the ca 400 attenuation loss as 0.7 for 100 foot at 30 mhz. Is there difference between the information between copper's information and the lmr 400 or am I not getting something right here. I TRUST YOUR ADVICE BUT, THIS INFORMATION ON THE CA 400 FROM COPPER'S HAVE THROWN ME FOR A LOOP. COULD YOU SHARE SOME MORE INFORMATION SO I CAN KNOW WHAT I AM DOING WRONG? |
Tech833
Moderator
Username: Tech833
Post Number: 1933
Registered: 8-2002
| | Posted on Thursday, March 17, 2011 - 10:53 am: |
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Good question.
Maybe it's time I bought a 100 foot length and did my own tests in the lab. I'll give it some thought.
Your radio 'Mythbuster' since 1998
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Charliebrown
Intermediate Member
Username: Charliebrown
Post Number: 178
Registered: 10-2002
| | Posted on Wednesday, April 13, 2011 - 9:00 am: |
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TECH 833, I KNOW YOU ARE VERY BUSY BUT, WHEN YOU HAVE DONE YOUR TEST ON THE LINE LOSS OF THE CA 400 CABLE PLEASE LET ME KNOW.I AM SURE EVERY ONE WOULD LIKE TO KNOW. BEFORE I PURCHASE 500 FOOT OF THIS CABLE I WOULD LIKE TO KNOW JUST HOW MUCH LOSS IT REALLY IS. |
Tech833
Moderator
Username: Tech833
Post Number: 1958
Registered: 8-2002
| | Posted on Saturday, April 16, 2011 - 1:01 am: |
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I just received a 1-foot sample of the line recently (thanks to Copper for providing the example). I plan to order a spool of the cable (at my expense) to do further testing. Please stand by.
Meanwhile, if you happen to order a 500' spool and would like to conduct some tests on it, let me know.
Your radio 'Mythbuster' since 1998
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Charliebrown
Intermediate Member
Username: Charliebrown
Post Number: 205
Registered: 10-2002
| | Posted on Sunday, June 26, 2011 - 9:57 am: |
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TECH 833, I NEVER GOT AROUND TO THE PURCHASE OF THE CA-600 BECAUSE A FRIEND OF MINE THAT HAS HIS OWN TV CABLE COMPANY NOW SOLD ME SOME P3-750 CABLE AT A VERY, VERY, LOW PRICE. IF YOU LOOK IT UP THIS IS A MUCH LOWER LOSS THAN THE CA- 600. THE ONLY THING IS THAT IT IS 75 OHM. NO BIG DEAL THOUGH. |
Tech833
Moderator
Username: Tech833
Post Number: 1995
Registered: 8-2002
| | Posted on Sunday, June 26, 2011 - 5:16 pm: |
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"Lower loss than CA-600" is only valid if the impedance is correct. Since your radio and antenna are expecting 50 ohm cable between them, the loss would be much higer. It's not apples and apples. It's apples and lemons.
Your radio 'Mythbuster' since 1998
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Dale
Senior Member
Username: Dale
Post Number: 1724
Registered: 12-2002
| | Posted on Sunday, June 26, 2011 - 5:57 pm: |
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tech 833 i ran across some interesting coax
jefatech.com. they speicialize in low loss cable
for amature radio and satilites. they bhave a low loss 400 series thats rated lower than lmr 400 at .067 at 100 feet 30 mhz.if your gonna test coax
dale/a.k.a.hotrod
cef426
cvc#64
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Charliebrown
Intermediate Member
Username: Charliebrown
Post Number: 207
Registered: 10-2002
| | Posted on Sunday, June 26, 2011 - 5:59 pm: |
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TECH 833, COULD YOU HELP ME AND TELL ME HOW MUCH DIFFERENCE YOU ARE TALKING ABOUT? I HAVE NO IDEA OF HOW TO EVEN FIGURE HOW MUCH LOSS DIFFERENCE. ALSO, IF YOU WOULD, COULD YOU TELL ME IF I NEED 50 OHM INSTEAD. WITH 500 FOOT OF LINE OUT I NEED AND WOULD LIKE TO GET AS MUCH POWER TO THE ANTENNA AS I COULD. THE ANTENNA ON THE TOP OF A HILL THAT FAR AWAY IS THE ONLY WAY TO GET A GOOD SIGNAL AND GET OUT WITH THESE VERY HIGH MOUNTAIN'S AROUND ME. |
Tech833
Moderator
Username: Tech833
Post Number: 1997
Registered: 8-2002
| | Posted on Monday, June 27, 2011 - 10:43 am: |
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Check your email, CB.
For runs like 500 feet, that is a good time to jump up to 1/2 or 7/8 inch Heliax.
Your radio 'Mythbuster' since 1998
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