Cable X-Perts RG-8 vs Davis Bury Flex

[J S-17]

I've read that Davis Bury Flex is very good (low loss) coax. I have
Cable X-Perts RG-8 (50 feet of it) as my feedline right now.  Is it
worth my time and $ making a change to Davis Bury Flex or something
similar?

Jeff
K6ATT
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[Jack Smith-6]

J S wrote:
> I've read that Davis Bury Flex is very good (low loss) coax. I have
> Cable X-Perts RG-8 (50 feet of it) as my feedline right now.  Is it
> worth my time and $ making a change to Davis Bury Flex or something
> similar?
>
Jeff:

You might ask yourself how much the loss differential would be between
the present cable and the proposed cable, for a length of 50 feet. You
can then decide whether the "dB per dollar" result makes sense, or not.

Evaluate the loss of the two cables at the highest frequency at which
you normally operate. My suspicion is that you will find the difference
is a fraction of a dB. Considering that even measuring power to an
accuracy of +/- 1 dB can be difficult without a decent wattmeter, you
might use that in evaluating the dB per dollar computation.

This assumes, of course, that your present cable is not defective.

Jack K8ZOA
www.cliftonlaboratories.com

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[Don Wilhelm-3]

Jeff,

My own 'rule of thumb' is that 2 dB less loss in your coax is worth it,
1 dB is not worth the money or trouble.

You will have to figure the relative loss for your highest band of
operation, your cable length, and your SWR on the line.  All of those
factors should be considered.

In other words, the worst RG-8 listed in the ARRL Antenna Book has a
loss of 1.9 dB per 100 feet at 100 MHz - so your 50 foot length will
have only 0.85 dB loss at 100 MHz (less at lower frequencies).  The loss
will not go below 0.0 dB in any case, so by my 1 dB 'rule', it is not
worth replacing.

OTOH, if you are running that RG-8 at a 5:1 SWR, The loss will increase
by 0.7 dB which gives you a total loss of 1.5 dB at 100 MHz - still not
enough to be gained to make it worthwhile for me, especailly if used on
HF.  YMMV.

Note: I have a 150 foot run of coax before I reach the antenna field or
go up a tower or mast, so it only takes a small reduction in loss at
that length to make me think about a change, but for a 50 foot run, I
would not bother.

73,
Don W3FPR

J S wrote:
> I've read that Davis Bury Flex is very good (low loss) coax. I have
> Cable X-Perts RG-8 (50 feet of it) as my feedline right now.  Is it
> worth my time and $ making a change to Davis Bury Flex or something
> similar?
>
> Jeff
> K6ATT
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[Tom Hammond-3]

Hi Jeff:

>I've read that Davis Bury Flex is very good (low loss) coax. I have
>Cable X-Perts RG-8 (50 feet of it) as my feedline right now.  Is it
>worth my time and $ making a change to Davis Bury Flex or something
>similar?

Personal opinion follows... take it for what little it may be worth...

The Davis RF Bury-Flex is just about equivalent to Belden 9913
low-loss coax, BUT it's better in the respect that it can be directly
BURIED for long periods of time with little degradation in the
polyethylene outer covering.

I use Bury-Flex exclusively between my Shack and the top of my tower,
a total of about 220' for each run.

This having been said, and for only a 50-foot run, used on HF, I'd by
lying if I said that you'd notice ANY substantive benefit from
switching from what you now have to Bury-Flex.

Good luck,

Tom Hammond    N0SS

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[Geoffrey Mackenzie-Kennedy-2]

Hi Tom,

Have you found this coax to be 'critter eat proof' or did you put it into
some type of pipe before burying?

73.
Geoff
GM4ESD

----- Original Message -----
From: "Tom Hammond" <[hidden email]>
To: "J S" <[hidden email]>; <[hidden email]>
Sent: Wednesday, March 21, 2007 11:43 PM
Subject: Re: [Elecraft] Cable X-Perts RG-8 vs Davis Bury Flex

> Hi Jeff:
>
>>I've read that Davis Bury Flex is very good (low loss) coax. I have
>>Cable X-Perts RG-8 (50 feet of it) as my feedline right now.  Is it
>>worth my time and $ making a change to Davis Bury Flex or something
>>similar?
>
> Personal opinion follows... take it for what little it may be worth...
>
> The Davis RF Bury-Flex is just about equivalent to Belden 9913 low-loss
> coax, BUT it's better in the respect that it can be directly BURIED for
> long periods of time with little degradation in the polyethylene outer
> covering.
>
> I use Bury-Flex exclusively between my Shack and the top of my tower, a
> total of about 220' for each run.
>
> This having been said, and for only a 50-foot run, used on HF, I'd by
> lying if I said that you'd notice ANY substantive benefit from switching
> from what you now have to Bury-Flex.
>
> Good luck,
>
> Tom Hammond    N0SS

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[Jack Smith-6]

I have released version 2.0 of Z90-Control software for the Z90/91
digital panadapters. It is available for download at
http://www.cliftonlaboratories.com/Software.htm..

Of  interest to this list is integration with the K2's remote control
interface. The new software adds the ability to click on a signal of
interest and see the actual frequency displayed. A second click will
automatically tune a K2 to that frequency.

Another K2 integration feature recognizes the K2's operating mode and
selects one of three IF frequency offsets. This solves a display
frequency error problem due to the way the K2 handles different modes
with a single crystal filter.

Also integrated for K2 owners is automatic sense inversion; so that
signals displayed on the left are always lower in frequency than those
to the right. Since the K2's frequency conversion scheme is
up-converting on some bands and down-converting on others, enabling this
feature avoids the need to recall upon which bands the frequency display
is inverted.

Note that the LCD display on the Z90 always remains in spectrum analyzer
sense mode; lower input frequencies are to the left of higher
frequencies. The automatic inversion applies only to the Windows display.

Other interesting and useful features have been added in release 2.0.

There is also a new firmware release for the Z91 that speeds up sweep
time about 2:1 by deleting code associated with the LCD.

Jack K8ZOA
www.cliftonlaboratories.com
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[David Cutter]

Good article in QEX on your system.

David
G3UNA

----- Original Message -----
From: "Jack Smith" <[hidden email]>
To: "Elecraft Discussion List" <[hidden email]>
Sent: Friday, March 23, 2007 6:49 PM
Subject: [Elecraft] K2 Integration with Z90/91 Digital Panadapter

>I have released version 2.0 of Z90-Control software for the Z90/91
> digital panadapters. It is available for download at
> http://www.cliftonlaboratories.com/Software.htm..
>
> Of  interest to this list is integration with the K2's remote control
> interface. The new software adds the ability to click on a signal of
> interest and see the actual frequency displayed. A second click will
> automatically tune a K2 to that frequency.
>
> Another K2 integration feature recognizes the K2's operating mode and
> selects one of three IF frequency offsets. This solves a display
> frequency error problem due to the way the K2 handles different modes
> with a single crystal filter.
>
> Also integrated for K2 owners is automatic sense inversion; so that
> signals displayed on the left are always lower in frequency than those
> to the right. Since the K2's frequency conversion scheme is
> up-converting on some bands and down-converting on others, enabling this
> feature avoids the need to recall upon which bands the frequency display
> is inverted.
>
> Note that the LCD display on the Z90 always remains in spectrum analyzer
> sense mode; lower input frequencies are to the left of higher
> frequencies. The automatic inversion applies only to the Windows display.
>
> Other interesting and useful features have been added in release 2.0.
>
> There is also a new firmware release for the Z91 that speeds up sweep
> time about 2:1 by deleting code associated with the LCD.
>
> Jack K8ZOA
> www.cliftonlaboratories.com
> _______________________________________________
> Elecraft mailing list
> Post to: [hidden email]
> You must be a subscriber to post to the list.
> Subscriber Info (Addr. Change, sub, unsub etc.):
> http://mailman.qth.net/mailman/listinfo/elecraft   
>
> Help: http://mailman.qth.net/subscribers.htm
> Elecraft web page: http://www.elecraft.com

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