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   Home   Help Search  
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Author Topic: mystery coax, need specs  (Read 2902 times)
KD8FVP
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Posts: 6




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« on: November 02, 2007, 06:53:52 AM »

DEC 70-248-01 BNCI-20 THICK COAXIAL CABLE 20m/60 feet Digital P/N 17-01551-03 Another P/N: BNCI-20 Rev. A On the cables it says: DEC P/N 1700248-01 REV. C SIGNAL COAX 1470 AWM.  I have some of this coax, and cant find the specs anywhere, and this makes no sense:

PRODUCT SPECIFICATIONS

  Atténuation. dB/100m @ MHz  
Type  Imp F.V.% pF/m 1 5 10 30 50 100 1000 Diam. Cond. Diel
MONTROSE 1700248-01 50 77 83,64 0,82 1,64 2,30   4,59 6,23   .410 #12 Foam P.E.

I need to know the loss in db/100ft @ 400 mhz Please Help, links to 2 ebay items that talk about it with photos:
http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=180082225503&category=48637

http://cgi.ebay.com/DEC-17-00248-01-BNCI-20-THICK-COAXIAL-CABLE-20m-60-feet_W0QQitemZ260010557344QQihZ016QQcategoryZ3704QQrdZ1QQssPageNameZWD1VQQcmdZViewItem

Thanks, new to the site, hope someone can help.  I want to use this for 2m/440.  Is it any good?

kd8fvp
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K7KBN
Member

Posts: 3676




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« Reply #1 on: November 02, 2007, 08:01:03 AM »

The specs seem to read in two lines --

Type:  Montrose 1700248-01

Impedance:  50

VF%: 77

pF/M (picofarads per meter): 83

1.5 (attenuation @ 1.5 MHz per 100 feet): 0.64 dB
10:   0.82 dB
30:   1.64 dB
50:   2.30 dB
100:  4.59 dB
1000: 6.23 dB

Diam:  .410"

Cond: #12

Dielectric: Foam P/E

The figures for attenuation may actually be specified in terms of 100 meters rather than feet (because the capacitance is specified in "per meter").  For figuring loss of a particular length at a particular frequency, you'll have to interpolate.
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73
Pat K7KBN
CWO4 USNR Ret.
AC5E
Member

Posts: 3585




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« Reply #2 on: November 02, 2007, 08:05:07 AM »

Well, I would be more helpful if I could get the link to work, but from the information given it seems to be a more or less generic "RG8 Foam" type coax that would be OK on VHF for short runs in non critical applications.

30 feet to an omnidirectional "repeater hitter" should be fine, but if you plan on using 200 feet to a stacked set of beams you need larger and lower loss transmission line.

73  Pete Allen  AC5E
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WB2WIK
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Posts: 21836




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« Reply #3 on: November 02, 2007, 08:21:13 AM »

Attenuation is 4 dB/100' at 400 MHz, nominally.

Same as it is for all other .410" OD cellular PE dielectric #12AWG conductor coax.   What determines this is its construction, not its model number.

A reasonable reference for comparison is Belden #8214.

WB2WIK/6
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N3JBH
Member

Posts: 2358




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« Reply #4 on: November 02, 2007, 12:31:45 PM »

Now that WB2WIK/6 gave you a cable# to compare you can check this site for some basic information... Jeff

http://hamradio.arc.nasa.gov/coaxcableloss.html
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KD8FVP
Member

Posts: 6




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« Reply #5 on: November 02, 2007, 05:28:29 PM »

to the first poster above, isn't that in 100 meters per db?  and also thanks every body.  It seems to be too lossy for 440, is that correct?  I have 32 ft, and wanted to use it on my ht to a 2m/440 j pole arrow antenna..

thanks
peace.
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N3JBH
Member

Posts: 2358




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« Reply #6 on: November 02, 2007, 06:51:38 PM »

If the 32 feet is all you need and you have it. i would use it. If your really worried about a big signal i reconsider the antenna aswell. But using a J-Pole antenna leads me to think your just wanting to do some local and most likely FM work it be fine.
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