[HCARC] Question for Mr Bill on LMR-400
Kerry Sandstrom
kerryk5ks at hughes.net
Sat Aug 18 14:26:26 EDT 2012
Gary,
I don't think Bill answered the question you asked. I think you asked if
all LMR-400 type cable is the same. The designation LMR-400 is owned by
Times Microwave. Only Times can legally mark their LMR-400 cable as
LMR-400. MIL-C-17 and RG on the other hand are mil spec cable designations.
Anyone can and does use those designations. If you want to sell the cable
to the government you have to show that your cable meets the appropriate
specs. These specs call for particular dimensions and specific materials as
called for in the spec. If you are not selling to the government, you can
do whatever you can get away with as Radio Shack/Tandy did several years ago
when they reduced the amount of copper braid in their cables.
Radio Shack/Tandy also played fast and loose with the performance specs
several years ago on RG-8X cable. They advertised some really good loss
specs on their cable. QST did a quick item on the cable talking about how
great it was. a couple months later, somebody took the time and measured
the actual loss of the cable and found it was not nearly as good as
advertised. Moral of the story is know who made the cable and base your
trust on that.
Getting back to LMR-400. If the cable is marked as such it is either from
Times or is an illegal copy. If it is described as equivalent to LMR-400,
then you have to decide what that really means. There is no magic in coax
cables. The same dimensions and the same materials will give the same
performance no matter who made it.
As I mentioned earlier, be sure the cable you buy is made with PVC type II
or IIA non-contaminating jacket if you want it to last more than 5 years.
I think Bill and I both agree, for use at low HF frequencies LMR-400 is
overkill.
Kerry
More information about the HCARC
mailing list