Like the subject asks, are the "generic" versions of LMR-400 and LMR-400
Ultraflex as good as the "name brand" or is it not worth the savings? Time for
new coax, so I wanted to get input from those who are familiar with both before
buying either.

Thanks, and 73,
Bob KB2ZGN

Hello Bob,
You asked a good question, but you are not going to like the answer.
Good and cheap does not walk hand in hand.

The reason why the established companies are head and shoulders above the generic equivelent is because the established companies has a much higher quality standard.

LMR 400 is a two edge sword.
Yes it is good, but it is also slightly more cost and a lot less durable then other types of cable.

The main use for LMR 400 is the higher ranges of UHF due to the fact that it has a lower loss rate.

A few things to remember, its center conductor is 10 gauge / not 12.
Its shield is foil - braid, not copper conductor. Its dielectric is foam not poly.

You have to buy special connectors, you aren't going to screw a PL connector on it and you can't solder it.
You have to have crimp pliers - and the $2.50 or more PL connectors to use it.

The foam dielectric is hygroscopic - it attracts water and it's life span is maybe 10 years. You aren't going to put it up and walk away and 30 years later still be using it - because once the water gets inside of it, it is ruined.

The outer jacket is very fragile, if it gets a knick or gets damaged, you are going to have to either splice it or replace it.

If your work involves UHF - your needs would be better off met with Hardline then with LMR 400. There are radio towers out there with hardline that is 40 years old that is still in service.

Often times, if you know the right person, they will sell you used hardline for a lot less money then new LMR 400.. After all, unless they are going to build a repeater - they probably don't have any use for it.

I hope this is not information over load.

When using generic LMR 400 - you want to make sure to have it sweep tested before you put it up. The Chinese aren't real particular what they sell, and most times the deal is that there is a bad spot somewhere in the coax and that is the reason why they wholesale it with no name on it.

"Bob" wrote in message
...
Like the subject asks, are the "generic" versions of LMR-400 and LMR-400
Ultraflex as good as the "name brand" or is it not worth the savings? Time
for
new coax, so I wanted to get input from those who are familiar with both
before
buying either.

Thanks, and 73,
Bob KB2ZGN


Depends on what brands you are talking about being the 'generic' version. I
am using some of the Davis Buryflex that is similar to lmr400 ultra flex. I
like it very much and have ran the loss tests on it on 2 meters and 440 mhz
and it meets the specs. I have 4 runs of it to the beams on my tower
covering a tribander, 6, 2, and 440. They have been up about 5 years with
no noticable problems.

"Channel Jumper" wrote in message
...

LMR 400 is a two edge sword.
Yes it is good, but it is also slightly more cost and a lot less durable
then other types of cable.

The main use for LMR 400 is the higher ranges of UHF due to the fact
that it has a lower loss rate.

A few things to remember, its center conductor is 10 gauge / not 12.
Its shield is foil - braid, not copper conductor. Its dielectric is
foam not poly.

You have to buy special connectors, you aren't going to screw a PL
connector on it and you can't solder it.
You have to have crimp pliers - and the $2.50 or more PL connectors to
use it.

LMR400 has foil, but it also has about a 95% braided shield. It is as easy
to solder to as any other rg8 type of coax with a braded shield. A standard
PL259 fits it just fine. Atleast all the ones I have used do. If using
some N type connectors the center pin needs to be specified as the
lmr400/9913 type due to the larger center conductor.

The dielectric is fine also. It is no worse than any other coax. It is not
like the origionaal 9913 coax that was a hollow tube that could fill with
water. I had 2 runs of that up about 50 feet to the antennas and did not
have a water problem in about 10 years. It was still dry when I took it
down for a move.


Still not sure about what you are calling the 'generic' coax. There is some
sold by TheWireMan with his brand. He does not make it, but buys it from
another company. That seems to be as good as any other of the same type
going on my sweeping two 100 foot rolls of the LMR 400 type and 100 feet of
a coax of a differant type from him from about 30 to 1000 MHz. Same as the
Davis Bury Flex. That Bury Flex is tougher to work with than some.

One indication the coax is not very good quality is if the braid is less
than about 90%. The beter ones should be atleast 95%. Most of the loss in
coax is in the center conductor and then the braid. That is up to around
1000 MHZ. But after that, most are not going to use coax anyway.

On Wed, 6 Mar 2013 10:21:35 -0500, "Ralph Mowery"
wrote:


"Bob" wrote in message
.. .
Like the subject asks, are the "generic" versions of LMR-400 and LMR-400
Ultraflex as good as the "name brand" or is it not worth the savings? Time
for
new coax, so I wanted to get input from those who are familiar with both
before
buying either.

Thanks, and 73,
Bob KB2ZGN


Depends on what brands you are talking about being the 'generic' version. I
am using some of the Davis Buryflex that is similar to lmr400 ultra flex. I
like it very much and have ran the loss tests on it on 2 meters and 440 mhz
and it meets the specs. I have 4 runs of it to the beams on my tower
covering a tribander, 6, 2, and 440. They have been up about 5 years with
no noticable problems.


Thanks for all the information. Of course, when I said "name brand" I was
referring to the Times Microwave LMR-400 Ultraflex. As for the "generic" brands,
I have to apologize for not being able to give you specifics, I have seen
several different names referenced when searching, especially on eBay, but on
some other sites as well. I will be sure to look out for the Davis Buryflex the
next time I do a search. I plan on using it for 80m to 6m to one antenna, and 2m
and 70cm to another.

What gave me pause, and want to talk to those who may be familiar with this
issue, was the difference in prices. Times Microwave coax is easily 30 to 40
percent more expensive, and while I am not a cheep skate, neither would I like
to waste money if the difference is not warranted. I just checked out the Davis
site, http://www.davisrf.com/buryflex.php and for lengths less than 100 feet,
the price is 95¢/foot, and less than 499 feet is 89¢/foot, very good prices
compared to the Times Microwave prices. Looks like I need look no further.

Thanks again Ralph for your input, it is very much appreciated.

73, Bob KB2ZGN

"Bob" wrote in message
...

Thanks for all the information. Of course, when I said "name brand" I was
referring to the Times Microwave LMR-400 Ultraflex. As for the "generic"
brands,
I have to apologize for not being able to give you specifics, I have seen
several different names referenced when searching, especially on eBay, but
on
some other sites as well. I will be sure to look out for the Davis
Buryflex the
next time I do a search. I plan on using it for 80m to 6m to one antenna,
and 2m
and 70cm to another.

What gave me pause, and want to talk to those who may be familiar with
this
issue, was the difference in prices. Times Microwave coax is easily 30 to
40
percent more expensive, and while I am not a cheep skate, neither would I
like
to waste money if the difference is not warranted. I just checked out the
Davis
site, http://www.davisrf.com/buryflex.php and for lengths less than 100
feet,
the price is 95¢/foot, and less than 499 feet is 89¢/foot, very good
prices
compared to the Times Microwave prices. Looks like I need look no further.

Thanks again Ralph for your input, it is very much appreciated.

73, Bob KB2ZGN

There are several things to look for in the coax. First look at the center
conductor. The larger the beter as that is where most of the loss is. Solid
wire will have slightly less loss, but if used with a rotator, it can flex
enough to break over the years. Then look at the shield, especially the
braid. It should be around 95% or beter. This is where the next loss is.
Most of the low loss coax has a foil type shield plus 95% or beter braid.
That applies for under 1000 Mhz anyway. Look at the velocity factor. The
low loss will normally be .80 or higher.

Davis BuryFlex is good. Belden is good, but stay away from the origional
9913. That hollow tube can fill with water if used outside. I had a couple
of runs of it up for about 10 years with no problems, but many have had
problems.

It pays to get some good coax as it should last for many years. In my case
I put up 4 beams on a tower and it is going to be a lot of trouble to
replace it if I ever have to.


At the priceof coax, you do want to spend a little more, but no need to pay
more than needed.

Also get some good connectors. Especially the ones going next to the
antenna as they are hard to replace.

Jef wrote:

First look at the center
conductor. The larger the beter as that is where most of the loss is. Solid
wire will have slightly less loss, but if used with a rotator, it can flex
enough to break over the years. Then look at the shield, especially the
braid. It should be around 95% or beter. This is where the next loss is.
Most of the low loss coax has a foil type shield plus 95% or beter braid.
That applies for under 1000 Mhz anyway. Look at the velocity factor. The
low loss will normally be .80 or higher.

Just to point out that the diameter of the centre conductor is fixed by
the impedance of the coax, the outer diameter, and the dielectric
constant of the insulator. So for a cable that will fit in a PL259 or N
type it means that you will only have a very limited choice or inner
diameters that are dependant on the dielectric used, and that dielectric
is likely to have just as significant effect on loss as the diameter of
the inner, more as the frequency goes up. However, lower loss insulators
generally have a lower dielectric constant which also mean a larger
diameter inner, for a fixed outer diameter.

Jeff

Also, it needs to be pointed out that the original poster asked about
differences in make of coax, while the discussion now focuses mainly
on type of coax.

Of course, that is a different topic. There are differences between
types of coax (solid center vs stranded, solid dielectrum vs foam
or air or helix or bamboo etc, foil shield vs braid or both), but
what the OP asked is if an LMR-400 from one manufacturer is equal
to an LMR-400 from another manufacturer.

In that case, the diameters, insulation types, braid types etc should
be the same and it is only thw manufacturing quality that would be
different.

However, always check. There always are manufacturers that try to
get away with using less copper in the braid, for example. Copper
is expensive these days.

On 09 Mar 2013 10:33:58 GMT, Rob wrote:

Jef wrote:

First look at the center
conductor. The larger the beter as that is where most of the loss is. Solid
wire will have slightly less loss, but if used with a rotator, it can flex
enough to break over the years. Then look at the shield, especially the
braid. It should be around 95% or beter. This is where the next loss is.
Most of the low loss coax has a foil type shield plus 95% or beter braid.
That applies for under 1000 Mhz anyway. Look at the velocity factor. The
low loss will normally be .80 or higher.

Just to point out that the diameter of the centre conductor is fixed by
the impedance of the coax, the outer diameter, and the dielectric
constant of the insulator. So for a cable that will fit in a PL259 or N
type it means that you will only have a very limited choice or inner
diameters that are dependant on the dielectric used, and that dielectric
is likely to have just as significant effect on loss as the diameter of
the inner, more as the frequency goes up. However, lower loss insulators
generally have a lower dielectric constant which also mean a larger
diameter inner, for a fixed outer diameter.

Jeff

Also, it needs to be pointed out that the original poster asked about
differences in make of coax, while the discussion now focuses mainly
on type of coax.

Of course, that is a different topic. There are differences between
types of coax (solid center vs stranded, solid dielectrum vs foam
or air or helix or bamboo etc, foil shield vs braid or both), but
what the OP asked is if an LMR-400 from one manufacturer is equal
to an LMR-400 from another manufacturer.

In that case, the diameters, insulation types, braid types etc should
be the same and it is only thw manufacturing quality that would be
different.

However, always check. There always are manufacturers that try to
get away with using less copper in the braid, for example. Copper
is expensive these days.

Thanks to you, Ralph, and Jeff for your kind responses and some great
information - just what I needed. I've a little more research to do, but I got
the answers I was looking for, and more. I really appreciate it. This is a great
group.

73, Bob KB2ZGN

在 2013å¹´3月6日星期三UTC+8下å�ˆ9æ—¶33分11ç§’ï ¼ŒChannel Jumper写é�“：
'Bob[_32_ Wrote:


When using generic LMR 400 - you want to make sure to have it sweep

tested before you put it up. The Chinese aren't real particular what

they sell, and most times the deal is that there is a bad spot somewhere

in the coax and that is the reason why they wholesale it with no name on

it.



Channel Jumper



The retrun loss can be better than 26dB from 5Mhz to 3G,we supply CNT400 for ANDREW.

On Wednesday, March 6, 2013 at 2:08:54 AM UTC-8, Bob wrote:
Like the subject asks, are the "generic" versions of LMR-400 and LMR-400
Ultraflex as good as the "name brand" or is it not worth the savings? Time for
new coax, so I wanted to get input from those who are familiar with both before
buying either.

Thanks, and 73,
Bob KB2ZGN

I use Times LMR 400 and have had it up for 20 years without any degradation. I had the opportunity to shorten a piece and test it to it's standards. I am a PhD EE and therefore have access to a whole lab of RF tols. It met it's original specs.

Michael V Taylor
AL1N