LMR400 handles 3.5kw average, 11kw pep and provides 50db. more shield attenuation than does the 8X-8Mini series feedline.
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better coax
- Thread starter Jay in the Mojave
- Start date
Distributor,
How far can you run openwire? Depends on how it's supported, and how far you have to go (anything over about a 1/2 mile is sort of unreasonable). Lot less loss compaired to any coax, usually doesn't 'care' what the SWR is, and isn't that hard to match to whatever the transmitter's output impedances is. Use a good tuner at the transmitter and it all works just fine almost on any band/frequency. Sound too good to be true? There are some "but's" to it, but not many and those aren't all that impossible to 'get around'. Why isn't open-wire used more than coax, cuz there are some things that are definitely not 'good' with using it. Can't lay it on the ground, bundle it with other cables, or coil it up, being the most common 'complaints'. It's also 'uglier' than coax, depending on who'z looking at it, naturally!
(If you couldn't tell, I like open-wire, don't mind using tuners and 'twiddling' knobs.)
- 'Doc
PS - There are things about open-wire feed lines that you definitely have to experience to believe. For instance, the stuff likes to 'swarm' if turned loose. Picking out a 'back-lash' in a fishing reel is very good practive - LOL!
How far can you run openwire? Depends on how it's supported, and how far you have to go (anything over about a 1/2 mile is sort of unreasonable). Lot less loss compaired to any coax, usually doesn't 'care' what the SWR is, and isn't that hard to match to whatever the transmitter's output impedances is. Use a good tuner at the transmitter and it all works just fine almost on any band/frequency. Sound too good to be true? There are some "but's" to it, but not many and those aren't all that impossible to 'get around'. Why isn't open-wire used more than coax, cuz there are some things that are definitely not 'good' with using it. Can't lay it on the ground, bundle it with other cables, or coil it up, being the most common 'complaints'. It's also 'uglier' than coax, depending on who'z looking at it, naturally!
(If you couldn't tell, I like open-wire, don't mind using tuners and 'twiddling' knobs.)
- 'Doc
PS - There are things about open-wire feed lines that you definitely have to experience to believe. For instance, the stuff likes to 'swarm' if turned loose. Picking out a 'back-lash' in a fishing reel is very good practive - LOL!
You can run it as far as you want; however, it needs to be installed clear of metallic structures for several inches all around it. It also needs to be twisted a bit - maybe two twists per six feet of length (this makes a difference in how it reacts to wind). You need a balun to make the transition from open wire to coax, and at the antenna end you'd just connect the open wire to the doublet or other wire antenna.
Oh - and you need to use a matching network at the transmitter end.
I suppose one could install another balun and feed a yagi or other unbalanced antenna...
Oh - and you need to use a matching network at the transmitter end.
I suppose one could install another balun and feed a yagi or other unbalanced antenna...
how can so many of you give such high praise to LMR-400 coax
in my book LMR-400 is simply ok coax for
this is barly better then RG-213 coax
LMR-400 is entry line of the better coaxes
the RG-217 is ok but not as good as modern high end coax
Myself i use andrews heliax LDF5-50A for HF with N connecters (LDF7-50A VHF/UHF)
however this stuff is expensive and hard to work with compared to
LMR-400
Heck even Jay has his I-10K availible for use with this hardline coax
that uses the better N connectors for better water repealing
the only good coax spoken of was the 600 ohm later line coax
great stuff and extremly low loss but also a bit more difficult to use (but well worth the effect)
Do not fool yourself to thinking LMR-400 is top line coax
is sort of akin to comparing C biased amp to AB1 biased amp
here are specs of Andrews Heliax LDF5-50A
which by the way is warrentied for 10 yrs
this is what install and leave it be is about
http://www.tessco.com/products/displayProductInfo.do?sku=471168&eventPage=3
here is your LMR-400 (Edit: This link is NOT for LMR-400!)
http://www.tessco.com/products/displayProductInfo.do?sku=67906&eventPage=1
and for the heck of it here is RG8x
http://www.tessco.com/products/displayProducts.do?groupId=403&subgroupId=15
in my book LMR-400 is simply ok coax for
this is barly better then RG-213 coax
LMR-400 is entry line of the better coaxes
the RG-217 is ok but not as good as modern high end coax
Myself i use andrews heliax LDF5-50A for HF with N connecters (LDF7-50A VHF/UHF)
however this stuff is expensive and hard to work with compared to
LMR-400
Heck even Jay has his I-10K availible for use with this hardline coax
that uses the better N connectors for better water repealing
the only good coax spoken of was the 600 ohm later line coax
great stuff and extremly low loss but also a bit more difficult to use (but well worth the effect)
Do not fool yourself to thinking LMR-400 is top line coax
is sort of akin to comparing C biased amp to AB1 biased amp
here are specs of Andrews Heliax LDF5-50A
which by the way is warrentied for 10 yrs
this is what install and leave it be is about
http://www.tessco.com/products/displayProductInfo.do?sku=471168&eventPage=3
here is your LMR-400 (Edit: This link is NOT for LMR-400!)
http://www.tessco.com/products/displayProductInfo.do?sku=67906&eventPage=1
and for the heck of it here is RG8x
http://www.tessco.com/products/displayProducts.do?groupId=403&subgroupId=15
I was wanting to connect it to an omni or a beam on a hilltop I own its atleast 500 ft more in elevation then the house.
Already have posts running to the top of the hill for a fence, Can you guys point me in the direction of what all I would need to hook this up.
T.I.A.
Sorry for being a NOOB
Already have posts running to the top of the hill for a fence, Can you guys point me in the direction of what all I would need to hook this up.
T.I.A.
Sorry for being a NOOB
A 'noob'? What's wrong with that? Just means you haven't been around long enough to make all the 'other' mistakes that some of us have.
What would you need to use ladder line? Well, you've already got the poles, so you'd need some way of mounting the line on them. A length of PVC pipe three or four times the width of the ladder line would work. Connect that pipe to the PVC/plastic spreaders of the ladder line. Go to the next pole, etc. If you don't want to use a balun on both ends of the run of ladder line, you don't really have to. A yagi with no matching device at the feed point is a balanced antenna. The 'slip-rings' needed to be able to turn the thing are not exactly all that common, but not really all that hard to make, sort of. A vertical with the appropriate counterpoise / groundplane is a balanced antenna too. Does need a bit of tuning to get it tight though. The cheap and dirty way of taking care of the transmitter end of the run is to just run it into the shack to a tuner (most bigger/larger/better tuners have a balun already in them). Then coax to the transmitter, whatever.
There will be some loss doing it that way but there will be less than if you tried to run coax (any kind of coax!) for 500 feet and more.
- 'Doc
[If you get more than 500 feet of ladder-line and don't use it all... can I have what's left?? Don't want you to be out a lot so ship it the cheapest way you can. LOL]
What would you need to use ladder line? Well, you've already got the poles, so you'd need some way of mounting the line on them. A length of PVC pipe three or four times the width of the ladder line would work. Connect that pipe to the PVC/plastic spreaders of the ladder line. Go to the next pole, etc. If you don't want to use a balun on both ends of the run of ladder line, you don't really have to. A yagi with no matching device at the feed point is a balanced antenna. The 'slip-rings' needed to be able to turn the thing are not exactly all that common, but not really all that hard to make, sort of. A vertical with the appropriate counterpoise / groundplane is a balanced antenna too. Does need a bit of tuning to get it tight though. The cheap and dirty way of taking care of the transmitter end of the run is to just run it into the shack to a tuner (most bigger/larger/better tuners have a balun already in them). Then coax to the transmitter, whatever.
There will be some loss doing it that way but there will be less than if you tried to run coax (any kind of coax!) for 500 feet and more.
- 'Doc
[If you get more than 500 feet of ladder-line and don't use it all... can I have what's left?? Don't want you to be out a lot so ship it the cheapest way you can. LOL]
Your book is FICTION and its clear you don't know the differences between LMR-400 and RG-213. LMR-400 is as close as you get to hardline without actually making the jump. Let me quote here:KingCobra_CDX882 said:
Your use of LDF is excellent, but that is NOT what we are currently discussing!
If someone wants an RG-8 type of coax, they will not do better than LMR-400.
I currently run LMR-600 with N-connectors on my I-10K. I also have FSJ-4, LDF-4 and LDF-5 hardline for other antennas.
Also, 600 ohm "ladder line" is NOT coax and your link for the LMR-400 is wrong. RG-400 and LMR-400 are two different cables!
Here is the CORRECT LINK FOR LMR-400
you'll lose (3db.) half the transmitter power or more to losses in a 500 foot run even if you do use LMR400. RG-213 has almost twice the loss of LMR400 when compared at the same frequency.
This argument comes up from time to time. I'm not sure I am doing the math correctly.freecell said:
With 500' of coax, and 100 watts out, only 50 watts will make it to the antenna.
If we put 1000 watts out, that's only 500 watts to the antenna.
3db is 3db, right? In other words, the more the power, the more the loss. Still, 500 watts is better than 50 watts, but the losses are HUGE as the power goes up!
Either way, the use of a quality coax is obvious!
Master Chief said:
I agree that using good coax is paramount. The dB rating listed as a specification is for a VSWR of 1:1. So if the antenna feedpoint impedance is not ideal (matched) then the dB losses will be more. These losses will increase at some proportionality constant with the square of the standing wave voltage.
Using THIS ever-popular coax calculator, you can enter whatever SWR your antenna actually has and it will figure SWR loss along with line loss for you.
"Wireman 554" open line, shown on this calculator, is a 440 ohm "window" line. 500 feet of it at 30 MHz with 1:1 SWR shows a total loss of 1.4 dB. At 2:1, the loss is 1.6 dB, and 3:1 is 2 dB. Remember that this is "window" line: conductors separated by a web of polyethylene with openings (windows) cut into it to reduce weight, wind sail area, and to decrease loss. Actual open line, with conductors separated by spacers with NO poly webbing, has even LESS loss.
One drawback of window line compared with coax is that coax is relatively unaffected by rain and heavy dew. Just for giggles, try this same search: at 30 MHz, with 500 feet of Wireman 554 WET:
1:1 shows a loss of 12.478 dB!!!!!! :shock:
2:1 12.988 dB :shock: :shock:
3:1 13.724 dB
"Wireman 554" open line, shown on this calculator, is a 440 ohm "window" line. 500 feet of it at 30 MHz with 1:1 SWR shows a total loss of 1.4 dB. At 2:1, the loss is 1.6 dB, and 3:1 is 2 dB. Remember that this is "window" line: conductors separated by a web of polyethylene with openings (windows) cut into it to reduce weight, wind sail area, and to decrease loss. Actual open line, with conductors separated by spacers with NO poly webbing, has even LESS loss.
One drawback of window line compared with coax is that coax is relatively unaffected by rain and heavy dew. Just for giggles, try this same search: at 30 MHz, with 500 feet of Wireman 554 WET:
1:1 shows a loss of 12.478 dB!!!!!! :shock:
2:1 12.988 dB :shock: :shock:
3:1 13.724 dB
rg213 over 500 feet with 1 to 1 swr shows loss of 5.525 db
lmr400 shows loss of 3.336 (yes much better)
but at 500 ft you need really good coax so
LDF5-50A shows loss of .976 (not even a full db in loss)
another good feedline being open 600 ohm with loss of .535
now if you are doing a 100 ft or less run it is not as importent in regards to the losses
but then true hardline will greatly outlast lesser grade coax
however true hardline is also hard to work with
for is very unflexible
as i said earlier
LMR400 is ok...but do not call it hardline...for it is not
although ladderline is great
it too has its own set of quirks in working with it
one must chose for themselves how much they are willing to spend and how they can work with the paticular ways of their coax
if one is running a beam then there is no way they can run directly to the beam for hardline will not allow the beam to turn
where LMR400 and LMR600 will
lmr400 shows loss of 3.336 (yes much better)
but at 500 ft you need really good coax so
LDF5-50A shows loss of .976 (not even a full db in loss)
another good feedline being open 600 ohm with loss of .535
now if you are doing a 100 ft or less run it is not as importent in regards to the losses
but then true hardline will greatly outlast lesser grade coax
however true hardline is also hard to work with
for is very unflexible
as i said earlier
LMR400 is ok...but do not call it hardline...for it is not
although ladderline is great
it too has its own set of quirks in working with it
one must chose for themselves how much they are willing to spend and how they can work with the paticular ways of their coax
if one is running a beam then there is no way they can run directly to the beam for hardline will not allow the beam to turn
where LMR400 and LMR600 will