Wilson 5000 Magnet Mount Coax

[jazzsinger]

@ jazzsinger.. thank you for the knowledge. You really made sense!

Ok......

I just looked at my friends Wilson 5000 magnet mount on his car and it does come equip with an RG 58 C/U 50 Ohm (I don't know what the "C/U" means) but, it says that this can handle up to 5KW on AM. The length of the coax is 17FT. Now, this is all I'm concerned about is AM.

Is that for reals? 5KW watts on AM on this coax??

I'm already thinking of changing the coax to an LMR 240 (18FT) to be specific.

Do anyone know where I can get the PL-259 for this 'skinny' type coax because I'm definately upgrading the coax on this Wilson 5KW?

Any help is greatly appreciate it.. Thanks in advance!

5kw on rg 58c/u sounds seriously optimistic, be closer to 500 watts with a 1.0:1 vswr dropping in handling with higher vswr.

lmr 240 has a different velocity factor to rg 58 c/u, so it won't be 18 feet, according to times microwave data,the company that makes lmr 240, its velocity factor is .84 or 84%.

to find a 3/4 wave length of lmr 240 centred on 27.185 mhz:

300/27.185 = 11.03m x .84 (vf) = 9.27m x.75 (3/4 wavelength) = 6.95m or (multiply by 3.28 to convert to feet) = 22 feet 9 1/2 "


as you can see for the same 3/4 wavelength of coax in lmr 240 as there was in the previously fitted rg58c/u then due to the velocity factor difference there is a physical length difference of about 4 feet.


you can change the velocity factor in that formula for different cables, and you can change the wavelength fraction to .25 for a 1/4 wave or .5 for a halfwave depending on your requirements, you can also change the 27.185mhz centre frequency for any centre frequency you prefer, the formula will still give you the approximate length your desired cable should be.

you will see very little benefit in replacing the coax as rg58c/u is decent enough for such a short run, unless you plan on running power levels above rg58 c/u's approx 500w rating. i'd be very surprised if the wilson will handle 5kw either, especially as its supllied with coax that deffo isn't up to that job.

you should be able to get plugs for lmr 240 from dealers that sell lmr 240, and for rg58 c/u the best bet is to use an amphenol 83-1sp plug (original pl259) with a reducer amphenol part 83-185(rfx) or more commonly known as ug175/u .

 

[loosecannon]

to all,

the theory being discussed is all valid as far as i know, but as for whether or not these things will make a difference in installing a wilson antenna; my answer is probably not.

everything i say from here on is from personal experience, not hearsay.

the coax supplied with the wilson 1000 antenna is Rg-58 type. 50 ohms.

the coax supplied with the wilson 5000 is RG-8x type. 50 ohms.

if you purchase a wilson 5000 magnet mount antenna, it will come with the RG-8x coax on the mag mount.

if you purchase an aftermarket "wilson type" mag mount, it will come with RG-58 coax on the mag mount.


you can cut the coax to almost any length you want, and the antenna will still provide a low SWR.

i say "almost" because there are certain specific lengths that may cause a false reading, but the chances of cutting the coax at EXACTLY this length are very, very slight.
even if you did somehow wind up with one of those magic lengths, as long as the wilson antenna is properly installed and tuned, you're probably not going to notice the tiny difference on your meter anyway.

bottom line, the coax length does not matter on the wilson antennas.

i have owned and replaced the coax on a wilson 1000 antenna and just cut the coax to be the length i needed without any regard to its length.
it matched up at about 1.2:1.
good enough for me.

i now own a wilson 5000 that i have also replaced the coax on (i step them up to LMR240uf for the shielding) and again, i paid no attention to what particular length i used, just used enough to get from A to B.
this antenna barely moves the SWR meter's needle.

why does wilson sell their antennas with 17 or 18 feet of coax?

because thats the standard length needed to get from the trunk of a car to the dashboard.
LC


edit to add two things.

first, if wilson was intending for the coax provided with their antennas to be a certain length in order for it to work correctly, then why do they use the same length with two different types of coax, each having a different velocity factor?

second, wilson rates their antennas at ICAS duty.
if you know what that is, then you know where they get that 5000 watt claim from. LOL
heck, my 60 watt dummy load will handle 500 watts for .5 seconds no problem!
LC

 

[WR0220]

...i have owned and replaced the coax on a wilson 1000 antenna and just cut the coax to be the length i needed without any regard to its length.

I had similar results about 3 yars ago when I replaced the coax on my Wilson 1000 (roof mount) with LMR-240UF coax. No trimming of the whip was needed, in fact I had to extend the whip a hair but SWR was =< 1.2:1 across the entire 11m band.