Thread: VHF cable type?
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Brian Whatcott
 
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Default VHF cable type?



Hi Larry W4CSC,

I think you need to take a look at the cable suppliers' specs before
telling us all about RG-58A/U 's wonderful features. Maybe take your
blood pressure medicine too?

Now about RG58A/U - this was the stuff you picked up for $10 at the
surplus store, wasn't it? :-) this spec is available new in
either foam OR solid insulation would you believe?

I checked several suppliers before writing this note: perhaps you
could check *your* facts too! You could start he

http://www.radialllarsen.com/docfiles/Cables.pdf


Brian Whatcott Altus OK

On Sat, 17 Jan 2004 06:01:33 GMT, (Larry W4CSC) wrote:

All these numbers mean NOTHING if you pull foam cable around a CORNER.
The solid center conductor migrates through the flimsy foam that gives
it such a great set of numbers and it goes all to hell......

Solid center conductors also BREAK if you bend them back and forth as
the loose cable in the mast moves back and forth and back and forth on
every wave.

RG-58A/U has the same loss AFTER you pull it than when it was on the
reel. It's very flexible, finely stranded center conductor and very
hard polyethelene dielectric will take a helluva beating with no
migration around tight turns.

Most boats I know have no room for inch and a half hardline from the
radio to the mast......dammit. 58A/U (not 58/U which is solid
centered) works great for years and years......It's made for MOBILE
service.



On Sat, 17 Jan 2004 03:42:59 GMT, Brian Whatcott
wrote:

I took a look at some sample specs to get a feel for the losses.

RG8X 7-9 dB/100 ft @ 400MHz
RG8U 4 dB/100 ft @ 400 MHz

You likely won't be operating at 400 MHz, but I'll use these figures
all the same. (Lower Fx is less lossy)

And I'll suppose that, what with the connectors, the loss is 8dB
versus 4 dB
That's 4 more dB

8 dB means you lose about 84% of your transmitter power.
4 dB means you lose about 60% of your power

So do you want 40 or do you want 16 ??

Brian Whatcott Altus OK

On Sat, 17 Jan 2004 00:46:44 GMT, "Lew Hodgett"
wrote:


"Bruce" writes:
I have to replace the wiring in my 58' mast plus 20' to my radio; my
question is this. RG 8x vs RG 8U.

snip

RG8U and support it with a messenger cable.

The difference in cost gets lost in the wash.

I use 1/16" S/S cable and secure the RG8U to it with tie wraps every 2'-3'.

If you don't support it, it will stretch and the impedance will change or so
I was told by a radio guru I trust.

HTH




Larry W4CSC