Jeff wrote in
:



I've been told that braid makes a great deal of difference to common
mode noise pickup, and that while a thin foil and loose braid is fine
at UHF it's not to be expected to do the same for HF.

Even if you accept the principle that foil is worse than braid for
common mode signals, where do you think these signals are coming from?
Unless the cables route close to the source of the interference then
your antenna is going to pick it up much more than any difference in
shielding.


True, but that's why I want it. It's to exclude HF noise made by anything in
the building. The antenna will be several tens of metres away. As the signals
I want are HF and perhaps high MF from that antenna, it seems unlikely that I
should go with a cable whose specs are too loosely defined, and all
interpretations of 'RG6' are now attempts to reduce cost while getting
acceptable performance at UHF.


http://www.abccables.com/info-rg59-vs-rg6.html is one of the more
descriptive texts I read. No RG6 that I have found fits the description
given there for HF. RG59 does though, as does BT2002. I think I'll be
going with that BT2002 anyway, never mind the expense. The waste of
time trying to avoid it is alone beginning to look more expensive than
the price difference.

I must admit I do not understand the theory that foil is worse than
braid at lower frequencies, foil gives 100% coverage and is usually in
addition to braid. Even if it the thickness of the foil that is in
question, I don't see how, according to the article that you linked to,
it " don't(sic) have the proper type of shielding ".


Well, that's why I'm questioning it here. Like Geoffrey Mendelson said in his
reply in the later thread on RG6 in this group, a lot of the posts I've seen
on the web say more about the posters making them. I think I'll get a better
signal here than on the web at large. No irritating forum signups before
posting, either.. That article does seem to have a few vague contradictions,
but I think the point about a thin foil that is adequate for UHF screening
being inadequate for HF is interesting, and I've seen that point claimed
before. I'm pretty sure I'm not going to get an answer for that from people
who are dealing with UHF or fast digital signals, and mainly from an
installer's point of view, if the equipment they're using will filter out HF
anyway. Their purpose is not the same as mine.

There may be an issue with terminating foil shields well but that is a
different matter.


I found an RG6 with copper braid, to take care of that. Cheap too, but only
if it works. If it doesn't it will be cheaper to go for better cable to start
with. I like that BT2002 with the double copper braid, but I'm not yet sure
if the difference justifies the cost, though judging by what some places
charge for RG6 it probably does..