[TowerTalk] Coaxial Cable Attenuation Chart

[Tyler Stewart]

Anthony R. Gold wrote:
> 
> In message <Pine.OSF.3.95.970925184752.17011A-100000@jekyll.sgate.com> Frank Donovan writes:
> 
> > Here's a copy of the coaxial cable attenuation chart.
> > The loss of 1/2" CATV cable is fairly close to RG-17 at HF frequencies.
> 
> >              1.8   3.5   7.0  14.0  21.0  28.0  50.0   144   440  1296
> >
> > LDF5-50A     .04   .06   .09   .14   .17   .19   .26   .45   0.8   1.5
> > FXA78-50J    .06   .08   .13   .17   .23   .27   .39   .77   1.4   2.8
> > 3/4" CATV    .06   .08   .13   .17   .23   .26   .38   .62   1.7   3.0
> > LDF4-50A     .09   .13   .17   .25   .31   .36   .48   .84   1.4   2.5
> > RG-17        .10   .13   .18   .27   .34   .40   .50   1.3   2.5   5.0
> 
> I find the CATV cable numbers suspect above 2m.  There is a much
> greater rise in attenuation from 144 to 440MHz for this one cable
> (more than a tripling of dB/100ft) than for the others.
> 
> Regards,
> --
>    Tony - G3SKR / W2TG                   email: tgold@panix.com
> 
> --
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You are correct to a point, Tony.  The numbers are highly suspect,
judging by data that I have from manufacturers.  However, Commscope and
Times in my books are only listed to 1000 Mhz.

I'll list the numbers I have from the Times catalog for T10, which is by
far the most common (and similar to Commscope in spec), and you guys can
fight over the interpolation.

BTW, I suspect the reason for slightly higher attenuation for a similar
sized cable is the smaller center conductor of 75 ohm cable.

Here are some numbers for 3/4" T10 "semiflex":

Freq	Db/100'
Mhz

5	.10
30	.26
50	.34
108	.50
216	.72
240	.77
270	.82
300	.86
325	.90
350	.94
375	.98
400	1.01
450	1.08
500	1.14
550	1.20
600	1.26
650	1.32
700	1.38
750	1.43
800	1.48
862	1.55
900	1.59
950	1.64
1000	1.68

It looks like the numbers are pretty close until you hit 440, which
should be about 1.07 rather than 1.7, and at 1296 it would be somewhere
right around 2.0

73, Ty K3MM

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