Wes Stewart wrote:
On Sat, 10 Dec 2005 06:27:18 -0600, "Charlie"
wrote:


Sounds like a flawed test setup.


Hah hah. Very funny.

If Roy says it's bad--it's bad.

Agreed!

On Sat, 10 Dec 2005 11:59:27 -0600, "Charlie"
wrote:

Have you looked at all the positive user's reviews at eHam about it?

User reviews are testimonial, not skilled measurement.

One might also want to check this link for another endorsement of Davis

Endorsements are just that, again, not skilled measurement.

The again one could just read what is posted at this link at the eHam
Elmer's Forum - all very positive

Being positive and being correct are not the same thing.

I'm saying what he saw

Roy and anyone else is perfectly capable of speaking for him(them)self
and telling us what he (they) saw. Interpretation is prone to
transcription error, a frequent element of testimonial and
endorsement.

1. Maybe he
2. Maybe he
3. Maybe he

There are no maybes. Within this group there are experts in every
sense of the word that are credentialed and experienced. Among this
group are several Metrologists who do or have done these kind of
things (determine loss) for a living.

4. etc etc etc....NO ONE else I can find dislikes this 9914!!!

Roy is not offering an expression of personal taste, he is merely
stating that products often suffer claim inflation, which we can
observe to be inflated further by uninformed testimony. He offered
one very specific counter-claim in a region of RF that is especially
prone to error from the horde of eham testifiers. Their possession of
exotic tools does not confer upon them the ability to correctly
determine power (and by that extension loss).

If you want to challenge a technical statement, you have to go to the
statement and examine it by parts. Ask for data. Ask for the
references (and I don't mean chapter citations). Look at the
computations. Rebutting with testimonials is useless as they only
serve vanity.

73's
Richard Clark, KB7QHC

The biggest problem needs to be solved - the fact that the shack is too far
from the antenna.
Move the darn shack and be done with it!

On Sat, 10 Dec 2005 18:40:43 +1300, "Ross Biggar"
wrote:

I am putting up a second tower , but it will be about 200feet from the shack
and about 70feet high.
What coax is recommended to reduce loss to a minimum,and to feed a multiband
beam with a 2kw amplifier.
Hard line excepted due to cost.

Ross,

Interesting to see use of such a long line. We have been reliably
informed that nobody uses more than 75' or so!

Starting with the question "what is wrong with commonly available
RG213", you would expect a loss around 2.4dB in a 100m run (200' + 70'
+ 30' tails) with an average VSWR of 1.5.

Given that the lowest ambient noise level on 20m is around 20dB above
typical receiver noise floor, the impact of 2.4dB of loss on receive
is insignificant.

On transmit, you will lose about 45% of your power in the line, so
with your 2KW (output?) amplifier, you will still have 1100W arriving
at the antenna. Will that do the job OK?

Is ladder line the panacea? Wireman 554 directly connected to a 50 ohm
load would have a loss of ~1.7dB and a little extra for baluns brings
you close to 2dB, so it is not a whole lot better than RG213. However,
if you used a 9:1 balun at each end, you would expect line loss of
~0.6dB and a little extra for baluns brings you close to 0.8dB. Now
that seems respectable. Problem is that you live in the land of the
long white cloud, and ladder line performance is degraded
significantly when wet, so it might not be acceptable in your
situation when wet.

Lets look at home made open wire line using 2mm copper spaced 150mm
for a 600 ohms line. If you used the same 9:1 balun at each end, you
would expect line loss of ~0.2dB and a little extra for baluns brings
you close to 0.4dB. Now that seems quite good. Anecdotally, such an
air spaced line is not affected significantly by weather / water, but
that will depend on the quality of the insulators and your rigging
methods.

Remember that the open wire solutions above need to be tuned feeders
or you will need an ATU. I suggest that you will need the ATU for
multi band operation, so you should allow another tenth of a dB or so
for ATU loss.

Someone will probably suggest that LDF6-50 (32mm (1.25") hardline)
could achieve 0.3dB loss, but could you afford it, would it be good
value?

Owen
--

I had a bad experience with Belden 9913 and if Davis 9914 has the same
mechanical properties, be careful. I taped some 9913 to a mast and
sometime later discovered it had been squished flat from the tight wrap
of electrical tape. I have also seen people ty-rap 9913 and destroy its
shape. If Davis 9914 has the center conductor suspended by a thin spiral
thing like 9913, I would not be surprised with varying performance when
bending it. Here is some coax that looks like better performance than
9913 or Davis 9914 (2.7dB/450MHz/100ft) has the same Polyethylene outer
jacket as Davis and is cheaper. Check
http://yanta.pair.com/jefatech/specs...LL400Specs.pdf
Mike

Charlie wrote:
I would recommend you take a look at Davis RF "BuryFlex" 9914. It is very
nearly the exact same loss per 100ft (within a couple tenths of a db) as
LMR400 and/or 9913. It can be directly buried in the soil with no other
provisions needed. It has an abrasion resistant non-contaminating jacket
that has a warranted 20 year service life. It is also quite affordable at
about $.60/ft. It is very flexible and indeed is fine even as rotator
loops. I use it on all bands I run from HF thru 6M and 2M. It uses standard
UHF or N connectors as well. Loss per 100ft at 400MHZ is 2.9db

Check it out here....

1. http://www.davisrf.com/ham1/coax.htm#buryflex

Owen Duffy wrote:
Interesting to see use of such a long line. We have been reliably
informed that nobody uses more than 75' or so!

Actually, the assertion was that 75' is about average. And
even this special case problem doesn't rise to the level of
your 100 meter example.
--
73, Cecil http://www.qsl.net/w5dxp

Mike wrote:
I had a bad experience with Belden 9913 ...

Me too. I just can't seem to keep water out of it.
--
73, Cecil http://www.qsl.net/w5dxp

If Davis 9914 has the center conductor suspended by a thin spiral
thing like 9913,

Davis BuryFlex 9914 does not have the center conductor suspended by a thin
spiral.
1. http://www.davisrf.com/ham1/coax.htm#buryflex

It amazes me that no one else (that I can find) has found Davis BuryFlex to
be "bad coax". It has been in production well over 10 years.
Moreover I am amazed how many of you are non-thinking lambs following along
head-to-tail after your shepherd.
And also Davis emphasizes in it's data that this coax is flexible enough for
rotator loops and yet one guy says it is "bad coax" and so everyone falls to
their knees and worships accordingly?

And as far as data goes...is this guys data more accurate then the Davis RF
company that has been in the wire and cable business
with engineering professionals on the payroll since 1980? Sheesh......take
off the blinders people.....thousands of miles of Davis 9914 have been
installed by government,commercial and amateur stations and just now we find
out it's "bad coax" after more than 10 years?

Somebody is asleep at the switch.......

--

Charlie


"Mike" wrote in message
. net...
I had a bad experience with Belden 9913 and if Davis 9914 has the same
mechanical properties, be careful. I taped some 9913 to a mast and sometime
later discovered it had been squished flat from the tight wrap of
electrical tape. I have also seen people ty-rap 9913 and destroy its shape.
If Davis 9914 has the center conductor suspended by a thin spiral thing
like 9913, I would not be surprised with varying performance when bending
it. Here is some coax that looks like better performance than 9913 or Davis
9914 (2.7dB/450MHz/100ft) has the same Polyethylene outer jacket as Davis
and is cheaper. Check
http://yanta.pair.com/jefatech/specs...LL400Specs.pdf
Mike

Charlie wrote:
I would recommend you take a look at Davis RF "BuryFlex" 9914. It is
very nearly the exact same loss per 100ft (within a couple tenths of a
db) as LMR400 and/or 9913. It can be directly buried in the soil with no
other provisions needed. It has an abrasion resistant non-contaminating
jacket that has a warranted 20 year service life. It is also quite
affordable at about $.60/ft. It is very flexible and indeed is fine even
as rotator loops. I use it on all bands I run from HF thru 6M and 2M. It
uses standard UHF or N connectors as well. Loss per 100ft at 400MHZ is
2.9db

Check it out here....

1. http://www.davisrf.com/ham1/coax.htm#buryflex

Charlie wrote:
Somebody is asleep at the switch.......

The great majority of humans who have ever lived
found it easier to follow than to think. (Just an
observation - I don't know anything about 9914.)
--
73, Cecil http://www.qsl.net/w5dxp

I'd be glad to compare results and methodologies with anyone else who
has measured this coax. It would be particularly interesting and
educational if someone else's results are significantly different from mine.

Roy Lewallen, W7EL

Charlie wrote:
If Davis 9914 has the center conductor suspended by a thin spiral

thing like 9913,

Davis BuryFlex 9914 does not have the center conductor suspended by a thin
spiral.
1. http://www.davisrf.com/ham1/coax.htm#buryflex

It amazes me that no one else (that I can find) has found Davis BuryFlex to
be "bad coax". It has been in production well over 10 years.
Moreover I am amazed how many of you are non-thinking lambs following along
head-to-tail after your shepherd.
And also Davis emphasizes in it's data that this coax is flexible enough for
rotator loops and yet one guy says it is "bad coax" and so everyone falls to
their knees and worships accordingly?

And as far as data goes...is this guys data more accurate then the Davis RF
company that has been in the wire and cable business
with engineering professionals on the payroll since 1980? Sheesh......take
off the blinders people.....thousands of miles of Davis 9914 have been
installed by government,commercial and amateur stations and just now we find
out it's "bad coax" after more than 10 years?

Somebody is asleep at the switch.......