Got your dig Roy.....kinda sad.....

--

Charlie


"Roy Lewallen" wrote in message
...
Good work, Greg. It's refreshing to see that some people, at least, are
still willing and able to do this rather than unquestioningly accept
manufacturer's data. Even if the data turn out to be accurate, the process
is truly educational.

The varying SWR while terminated with 50 ohms is consistent with the 45
ohm Z0 you observed. My piece of BuryFlex is right at 50 ohms, but I'm not
too surprised at this amount of variation given the foamed dielectric. I
measured 80% velocity factor, so if our respective measurements are good,
the velocity factor of your piece should be around 72%.

Roy Lewallen, W7EL

Roy Lewallen, W7EL, wrote:

I measured 80% velocity factor, so if our respective
measurements are good, the velocity factor of your piece should be
around 72%.

Ok, my curiosity got the best of me, and I decided to
to measure the velocity factor. My VNA software has
a "distance to fault" feature, and I "worked backwards",
which is to say that I measured a length of the
BuryFlex with a tape measure (27' 2"), and adjusted
the VF on the distance to fault tool until I obtained the
same physical length. The far end of the cable was
terminated with an open circuit.

I happened to start with the measurement frequency set
to 1 MHz. Lo and behold, the VF needed to compute the
same physical length was 72%, as you suggested.

My own understanding is that VF should be constant with
respect to frequency, so I decided to vary the test frequency.
I should have left well enough alone.

I picked 1, 2, 4, 8, 16, and 32 MHz. For those frequencies,
I measured the following VFs:

1 MHz = 72%
2 MHz = 73%
4 MHz = 75%
8 MHz = 80%
16 MHz = 79%
32 MHz = 79%

I'm rounding the VF to integer values, since I don't think that any more accuracy
can be claimed in this setup.


Since that result was a little surprising, I grabbed some mini 8 (8X)
that was nearby, about 51.25 feet. The published VF is 78%, and
I measured the following, at the same test frequencies:

1 MHz = 78%
2 MHz = 78%
4 MHz = 79%
8 MHz = 79%
16 MHz = 80%
32 MHz = 80%

With this cable, the VF appeared much more constant across the
1 to 32 MHz range.

Is there an explanation that fits with my measurements?

Greg, W8WWV

On Sun, 11 Dec 2005 17:22:16 GMT, "Greg Ordy"
wrote:

Here are my personal experiences and observations with "BuryFlex".

Hi Greg,

You've made a polished report with enough data, excellent graphics,
and concise narrative to closely examine some interesting issues. It
attended those points of batch process, service, variation across
types and time. This and your follow-on VF examination from Roy's
offhand observation have that Ham spirit.

What is more important is that you revealed errors (or aberrant
results) rather than brushing them under the rug. As this thread has
proven by increasing -ahem- testimony, not all specifications prove
out and sometimes those things not specified raise interesting
questions.

73's
Richard Clark, KB7QHC

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

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

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'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.......

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.......