Phil Wheeler wrote:
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!

Please, folks, I didn't say that Davis BuryFlex is bad. I said that
careful measurements of the one 100 foot piece I have show it to have
much more loss than the specification indicates, and that the loss is
variable with flexing and bending. It's possible that the piece I have
is somehow defective. Everyone can interpret and act on this or not as
they choose. But I certainly won't be installing this brand and type of
cable in a critical application without carefully testing it first.

Huge numbers of ravingly positive testimonials can be found for CFA
antennas, cryogenically treated oxygen-free speaker cable, astrological
forcasts, and homeopathic remedies. I'm not interested in testimonials
for those or for coax cable either, all for the same reason. But I'd
love to see the results of anyone else's measurements.

The 100 foot piece I have was purchased several years ago from The
Wireman, so I know it's the genuine article. (It's also marked as Davis
BuryFlex.) It's been inside and unused since.

Roy Lewallen, W7EL

TY Cecil...sadly that is the essence of this thread.....

--

Charlie


"Cecil Moore" wrote in message
et...
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 have emailed Davis RF and asked them to send me their test results. Yes
it will be interesting.

Roy..doesn't seem a bit odd that NO ONE ELSE in over 10 years of BuryFlex
production has cited these same alarming "test results".


--

Charlie


"Roy Lewallen" wrote in message
...
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.......

Charlie wrote:
I have emailed Davis RF and asked them to send me their test results. Yes
it will be interesting.

Roy..doesn't seem a bit odd that NO ONE ELSE in over 10 years of BuryFlex
production has cited these same alarming "test results".

No. My experience is that the vast majority of amateurs don't have the
ability and/or confidence and/or interest and/or equipment to make good
measurements. And lacking the ability to measure it, very few would be
able to discern the difference in loss. If my measurements are typical,
commercial and government users (if there indeed are any for this
particular cable type) would quietly reject the stuff on incoming
inspection and order something else.

I do have a high degree of confidence that my measurements are accurate.
I took a lot of care in characterizing the cable before using it for
making remote antenna impedance measurements in the course of a
consulting job. But it's entirely possible that the particular piece of
cable I have is defective. That would just point to a quality control
problem rather than overzealous specsmanship.

In your query of Davis, I hope you asked them if they routinely test
production batches for loss, and if so how often and when the last test
was run. It's possible that something in their process changed
relatively recently.

If no other reader of this newsgroup has some of this cable and the
ability to test it, I'll see if I can arrange for someone else to make
measurements and post results.

Roy Lewallen, W7EL

Roy the kind of test results you cited would be extremely evident whether
someone has a network analyzer or just an swr meter.
That defense is sorely transparent in my opinion. To suggest that most
amateurs would not even have any interest if their bent or coiled 9914
suddenly jumped off the scale for loss and mismatch is ludicrous to say the
least.

Let me be clear ...I am not disputing what you claim you got as test
results. My conclusion is either the 100ft length you had was bad or
something skewed your calibrated setup. My career was in microwave r&d and
I know that it takes repeatable test results to form a valid, verifiable and
publishable data.
This is not personal Roy....but it is somewhat stimulating.


--

Charlie


"Roy Lewallen" wrote in message
...
Charlie wrote:
I have emailed Davis RF and asked them to send me their test results.
Yes it will be interesting.

Roy..doesn't seem a bit odd that NO ONE ELSE in over 10 years of BuryFlex
production has cited these same alarming "test results".

No. My experience is that the vast majority of amateurs don't have the
ability and/or confidence and/or interest and/or equipment to make good
measurements. And lacking the ability to measure it, very few would be
able to discern the difference in loss. If my measurements are typical,
commercial and government users (if there indeed are any for this
particular cable type) would quietly reject the stuff on incoming
inspection and order something else.

I do have a high degree of confidence that my measurements are accurate. I
took a lot of care in characterizing the cable before using it for making
remote antenna impedance measurements in the course of a consulting job.
But it's entirely possible that the particular piece of cable I have is
defective. That would just point to a quality control problem rather than
overzealous specsmanship.

In your query of Davis, I hope you asked them if they routinely test
production batches for loss, and if so how often and when the last test
was run. It's possible that something in their process changed relatively
recently.

If no other reader of this newsgroup has some of this cable and the
ability to test it, I'll see if I can arrange for someone else to make
measurements and post results.

Roy Lewallen, W7EL

On Sat, 10 Dec 2005 17:15:44 -0800, Roy Lewallen
wrote:

If no other reader of this newsgroup has some of this cable and the
ability to test it, I'll see if I can arrange for someone else to make
measurements and post results.

Roy, this seems a case of brand loyalty vs objective measurement and
evaluation (albeit on a single sample).

You will change your mind based on more measurement data, either
strengthening your existing opionion or changing it.

Those with brand loyalty already know all they need to know, life is
comfortable.

You are talking different languages, and the only way there will be
agreement is if you capitulate (which would be unprincipled in the
absence of evidence).

Owen

I remember the fierce debates over 9913, there were nearly as many
words written about how fabulous it was, as there were words written
on how to keep water out of it.
--

"Ross Biggar" wrote in message
...
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.
Regards
Ross
ZL1WN

I needed conventional low loss coax on the job a few years ago. Boss was
paying for it, so I was not pinching pennies. Best I could find was the
Times LMR400. As I recall, the center conductor is #9; so, it may not fit
some brands of N connectors. Unlike the 9913, this will not soak up water.
The loss at 50 MHz is 0.9 db, vs 1.6 db for 213 (100 feet). I know you want
20 meters, but 50 MHz is the lowest frequency I have any numbers for.

Tam/WB2TT

Owen it is NOT brand loyalty. It is the publicly published data by RF Davis
(for the past 10+ years) vs. Roy's one-shot test setup some years ago. I'm
not out to discredit Roy...I even shook his hand once at a Hamfest.



--

Charlie


"Owen Duffy" wrote in message
...
On Sat, 10 Dec 2005 17:15:44 -0800, Roy Lewallen
wrote:

If no other reader of this newsgroup has some of this cable and the
ability to test it, I'll see if I can arrange for someone else to make
measurements and post results.

Roy, this seems a case of brand loyalty vs objective measurement and
evaluation (albeit on a single sample).

You will change your mind based on more measurement data, either
strengthening your existing opionion or changing it.

Those with brand loyalty already know all they need to know, life is
comfortable.

You are talking different languages, and the only way there will be
agreement is if you capitulate (which would be unprincipled in the
absence of evidence).

Owen

I remember the fierce debates over 9913, there were nearly as many
words written about how fabulous it was, as there were words written
on how to keep water out of it.
--

On Sat, 10 Dec 2005 19:46:15 -0600, "Charlie"
wrote:

Owen it is NOT brand loyalty. It is the publicly published data by RF Davis
(for the past 10+ years) vs. Roy's one-shot test setup some years ago. I'm
not out to discredit Roy...I even shook his hand once at a Hamfest.

We should be a little suspicious of manufacturers claims. Davis' can
be expected to support their product.

Roy's single poor experience is concerning, indicating either a
quality control issue, or more general non-compliance with spec (both
are issues for Davis). An independent test of stock cable and possibly
Roy's sample would be most interesting.

I know I have made measurements and adjustments at times and in
searching for possible explanations, the cable quality is on the
radar. In one of those cases, a mobile installation could not be
trimmed properly, and the Taiwanese RG58 centre conductor was so far
off centre, it was nearly touching the braid.

We have all cut cables up and found inconsistent braid weave, open
braid weave, voids in the dielectric, faulty stranding of inner
conductor, off centre centre conductors. It is those kind of issues
that downgrade a suppliers reputation, not their ability to select a
good cable sample for laboratory measurement.

Perhaps if you're a whiz, you should perform some measurements so you
can report first hand your experience.

We don't see the Davis stuff on this side of the world. The concept
seems a good one, PE sheath, braid+foil outer, foam dielectric,
stranded inner, but you have to ask yourself why they haven't
displaced Heliax and its copies. I suspect the reasons include IM and
noise issues associated with the braid+foil, mechanical issues with
the foam, and resistance to water. Experience with noise and IM
problems with braid+foil coax in fixed installations makes me wonder
how it stands up in a rigorous test of flexing for a rotator loop, not
anecdotal evidence, but a structured test.

Owen
--

On Sat, 10 Dec 2005 20:42:18 -0500, "Tam/WB2TT"
wrote:


"Ross Biggar" wrote in message
...
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.
Regards
Ross
ZL1WN

I needed conventional low loss coax on the job a few years ago. Boss was
paying for it, so I was not pinching pennies. Best I could find was the
Times LMR400. As I recall, the center conductor is #9; so, it may not fit
some brands of N connectors. Unlike the 9913, this will not soak up water.
The loss at 50 MHz is 0.9 db, vs 1.6 db for 213 (100 feet). I know you want
20 meters, but 50 MHz is the lowest frequency I have any numbers for.


LMR400: 300' at 14.2MHz with VSWR=1.5, loss~=1.5dB



Tam/WB2TT

--