RG58U vs RG58A/U

[Brett Howard]

So I went to come up with a quick run of coax to get a j-pole outside
and looked through three 50 foot chunks I had.  Two of them were RG58U
and one was RG58A/U.  I had nice ties on the RG58A/U and the RG58U had
tape on it that had gone sticky and I was going to have to clean up.  So
because of that reason I chose the RG58A/U and I stuck the first end
onto it.  I figured tomorrow I'd run it and finish things off...

However...  I just got to reading about it and while the RG58A/U has
similar specs its billed as only being normally used for the old thin
net networking stuff.  (which reminds me of probably how long I've had
this cable).  man its been a while since I wired my parents house up
with coax so that I could share my 33.6K modem over the thin-net to
multiple computers.  

Anyway is there any reason not to use the RG58A/U or a compelling reason
to use the RG58U over the RG58A/U?  I know I really should use something
other than RG58 if I'm going to be going any farther than the length of
run that would be needed for a mobile.  However at the moment the
repeaters that I'm looking to be able to get into with this antenna I
can hit with 5 watts (and the antenna in the same room with me).  Its a
just shy of 10 foot tall antenna in a room with 8 foot ceilings so its
not exactly "vertically polarized" either... ;)

~Brett (KC7OTG)

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[Geoffrey Mackenzie-Kennedy]

Hi Brett,

Certainly there are differences between RG58U and RG58A/U, but if the three
50ft lengths you have are quite old I would suggest that the best way to
decide which piece(s) to use would be to measure the insertion loss of each
50ft length at the frequency to be used, using a 50 +j0 load.

73,
Geoff
GM4ESD


Brett Howard wrote on Sunday, March 21, 2010 at 6:23 AM:

<snip>

> Anyway is there any reason not to use the RG58A/U or a compelling reason
> to use the RG58U over the RG58A/U?  I know I really should use something
> other than RG58 if I'm going to be going any farther than the length of
> run that would be needed for a mobile.  However at the moment the
> repeaters that I'm looking to be able to get into with this antenna I
> can hit with 5 watts (and the antenna in the same room with me).  Its a
> just shy of 10 foot tall antenna in a room with 8 foot ceilings so its
> not exactly "vertically polarized" either... ;)


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[Jim Brown-10]

On Sat, 20 Mar 2010 23:23:04 -0700, Brett Howard wrote:

>Anyway is there any reason not to use the RG58A/U or a compelling reason
>to use the RG58U over the RG58A/U?

Your question is a good one, and for the last month or so, I've been
working on a FAQ style tutorial to answer it (and a lot of others) about
coax and stubs. It's still a work in progress, but an in-progress version
is on my website.

http://audiosystemsgroup.com/Coax-Stubs.pdf

73,

Jim Brown K9YC


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[Guy, K2AV]

Hi Brett,

The following loss figures might influence what you do. Figures are
from Wireman's published reference book but can be found in numerous
sources.

Coax      dielectric         Loss for 100' @ 150 MHz  Notes

RG58U     solid pe            5.1 dB       solid center conductor

RG58AU   solid pe             6.8 dB      stranded center conductor, 19 strands

RG400     solid teflon         4.8 dB      teflon jacket, center cond
stranded silvered copper, double silvered copper shield, spec'd in
aircraft cabling

RG58 type    pe foam         4.9  dB       "CQ" brand sold by Wireman,
typical value for store brand foam

RG8X type    pe foam         3.5  dB             "

RG8 type     pe foam         1.5 dB              "

LMR500   pe foam             1.2 dB      High grade .5 OD 50 ohm coax.

If one is forced to use RG58/59 sized cable for various
considerations, and particularly if exposed to weather, as in
tie-wrapped to brakelines and such for a mobile installation, the 1.50
per foot RG400 is superior, used in aircraft cable assemblies for
VHF/UHF and is flexible enough to go around bends without deforming
the dielectric. It is also flame-proof, and cannot be overheated to
melting while soldering or melted by proximity to hot engine/exhaust
components.  It uses RG59 adapter (UG176) for PL259. Since all the
conductors are silver plated, minor water ingress does not ruin the
cable as silver oxide is highly conductive vs. copper oxide which
turns the shield into a green series resistor.  Unlike some of the
older high grade cable, RG400 is still being made new and can be
bought by the foot on eBay.

73, Guy.

On Sun, Mar 21, 2010 at 9:30 AM, Geoffrey Mackenzie-Kennedy
<[hidden email]> wrote:

> Hi Brett,
>
> Certainly there are differences between RG58U and RG58A/U, but if the three
> 50ft lengths you have are quite old I would suggest that the best way to
> decide which piece(s) to use would be to measure the insertion loss of each
> 50ft length at the frequency to be used, using a 50 +j0 load.
>
> 73,
> Geoff
> GM4ESD
>
>
> Brett Howard wrote on Sunday, March 21, 2010 at 6:23 AM:
>
> <snip>
>
>> Anyway is there any reason not to use the RG58A/U or a compelling reason
>> to use the RG58U over the RG58A/U?  I know I really should use something
>> other than RG58 if I'm going to be going any farther than the length of
>> run that would be needed for a mobile.  However at the moment the
>> repeaters that I'm looking to be able to get into with this antenna I
>> can hit with 5 watts (and the antenna in the same room with me).  Its a
>> just shy of 10 foot tall antenna in a room with 8 foot ceilings so its
>> not exactly "vertically polarized" either... ;)
>
>
> ______________________________________________________________
> Elecraft mailing list
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[N5GE]

On Sun, 21 Mar 2010 14:44:23 -0400, Guy Olinger K2AV
<[hidden email]> wrote:

http://www.timesmicrowave.com/cable_calculators/

There are some free software downloads at the above address for
calculating coax criteria for most of the standard coax types, not
just TMW cables.

Tom, N5GE

K3 #806 with SUB RX, PR6,
KRC2 and K144XV
K3 #1055 with PR6 and XV432
W1, 2 W2's and other small kits

http://www.n5ge.com
http://www.swotrc.net

>Hi Brett,
>
>The following loss figures might influence what you do. Figures are
>from Wireman's published reference book but can be found in numerous
>sources.
[snip]

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[Brett Howard]

Well that tells me that over a 50 foot run (which is the max of what
I'll have to do) I'm looking at a delta between the cables of a little
under a dB.  

I don't have a ton of ends around and I've already slapped onto the
lesser cable so I'll probably just go with that for now.  Later I plan
to get a hunk of RG-8 but thats for a date when I can get a bit more
height.  (probably after I sell this house and move somewhere else).

I really liked the idea suggested by others to run the two cables to a
R50+j0 load and measure loss.  Technically now that I think of it I
could make that measurement with only one connector on each length of
cable with my MFJ-259B.  It can measure loss to an open on the far end.

Appreciate all the thoughts gentlemen and the data.

~Brett (KC7OTG)

On Sun, 2010-03-21 at 14:44 -0400, Guy Olinger K2AV wrote:

>
> The following loss figures might influence what you do. Figures are
> from Wireman's published reference book but can be found in numerous
> sources.
>
> Coax      dielectric         Loss for 100' @ 150 MHz  Notes
>
> RG58U     solid pe            5.1 dB       solid center conductor
>
> RG58AU   solid pe             6.8 dB      stranded center conductor,
> 19 strands
>
>

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