BoatBanter.com - View Single Post

On Tue, 23 Aug 2005 18:45:33 GMT, (Bob) wrote:

On Tue, 23 Aug 2005 11:33:18 -0400, Gary Schafer
wrote:

On Tue, 23 Aug 2005 10:44:14 GMT, (Bob) wrote:

On Tue, 23 Aug 2005 07:51:35 +0200, "Meindert Sprang"
wrote:

i haven't seen one of those, but there are other factors which argue
against rg 58 when there are superior cables out there. the loss
factor is one...physics itself causes rg58 to be lossier than cables
like rg213 or rg 8. although this is not a factor for a short run,
depending on how long the run is, it could be an issue.

also, thicker cables are going to be more mechanically sound than
thinner cables.

The type of connector has little to do with how well the cable holds
up. You are supposed to provide support for the cable irrespective of
the connector. The connector is not supposed to support the cable. The
cable should be properly strapped down so the connector does not take
any load.

i agree. in a perfect world this would be true. but the fact is that a
connector with rg 58 is less able to handle mechanical stress than one
using a more robust cable. lots of boats have connectors attached
improperly.

Lots of boats have a lot of things improperly attached. That is no
evidence bigger is better unless you plan to swing from the cable.

As far as RG58 cable being no good, I suppose you might want to tell
Motorola and many other radio manufacturers about that. They have for
many years supplied that cable on their VHF and UHF mobile antenna
installations. And by the way the PL259 was the standard connector for
both too.

as someone pointed out here, the marine environment is different than
the land based one. for short runs not subject to stress rg 58, while
obsolete, can work. but it's ridiculous to use when when other,
superior cables are available.

Then I suppose all boat antennas should be fitted with hard line. Why
would you even want to use RG8 type cable if bigger cable is
available.
I was refering here to your stance that RG58 was a poor cable for VHF
and HF frequencies because of its loss.

In marine VHF antenna applications you will be hard pressed to find
any marine VHF antenna that comes with a length of cable pre attached
that does not use RG58 type cable.

agreed again. ease of installation, cost, etc. has alot to do with
it. rg 58 generally costs a few cents a foot less than its competitors

The fact is that it doesn't make any noticiable performance difference
either electrical or mechanical.

The size of a cable has little to do with its mechanical durability.
There are small cables that are much more robust than larger cables.
It all depends on how each is constructed.

we're comparing apples to apples here. coax cables of the type rg
8/213/58 have basically similar constructions. the diameter of the
cable DOES affect its mechanical stability when compared to cables of
similar construction.

Again, only if you plan to swing from the cable. As a matter of fact a
smaller cable is much easier to keep stable than a larger one on a
boat.

The amount of shielding of coax cable is of little importance in most
typical radio installations.

disagree. with the increasing amount of electronics on boats nowadays,
more shielding is better.

Coax with 70 or 80% coverage verses 100%
will not matter unless it is used in multicoupling or duplex systems
where high isolation is important. Otherwise you will not be able to
measure any difference in performance.

again, disagree. many people report GPS, electronic compass, and
computer problems when they key up their radios. of course some of
this is overload from the antenna, etc. but more shielding on the
cable reduces inteference to and from the radio.

You can bet that the problems are not from poor shielding of the coax
cable. How much leakage do you think coax has anyway? Even poor coax.

If running a cable for a VHF antenna up the mast of a sail boat I
would opt for an RG8 type of cable over the RG58 type for the lower
loss benefit. Other than that RG58 cable would be the choice for HF or
VHF unless I happen to have some extra RG8 type cable handy at the
time.

rg 58 losses become significant even at 10 meter HF frequencies.
---------------------------
to see who "wf3h" is, go to "qrz.com"
and enter 'wf3h' in the field

Regards
Gary