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

Hi Ross

300ft of RG213 maybe? Thats about 3.5dB loss at 30MHz assuming a 1.5:1
VSWR. At 14MHz its about 2.4dB loss.

LMR400 at about the same diameter as RG213 is just under half the loss.
Its also cheaper than RG213 but a bit harder to terminate into connectors.

RG6 may also be usable and much cheaper (being TV/CATV coax) as it has
only slightly more loss than RG213. Its 75 ohms though if thats an issue.

(http://www.ocarc.ca/coax.htm)

There will be a much lower loss if you use open wire feeder... You could
no doubt use broadband baluns at each end to change back to coax. You
could also make your own feeder probably much cheaper than using coax.

I seriously dont think the line loss figures in the coax mentioned above
are important for HF work. You are of course losing half your power at
higher freqs.

Cheers Bob W5/VK2YQA

Ross Biggar wrote:
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

for which band?

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


"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

Yes that is a good question, I forgot to mention.
primary use will be on 20m,
Thanks
Ross

"F8BOE" wrote in message
...
for which band?

Ross Biggar wrote:
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.

At HF and with low SWR, anything of RG213 size or larger should be OK as
regards cable heating... but in reality you are not aiming to reduce the
losses "to a minimum". You're actually making a three-way balance
between losses, availability and cost.

(Re availability and cost: people in the USA should note that Ross is in
New Zealand. Coax is heavy, and international shipping costs are
horrendous, so Ross has a much narrower range of options than you do.)

"Cost" will also include the cost of repairs and replacement - and this
can be a big consideration with a long run of cable because it's
extremely important to keep the jacket free from any damage where water
can get in. Capillary action can suck water into the braid over very
long distances from the initial location of the damage, and corrosion of
the braid can drastically increase the losses. So even minor physical
damage can have big electrical consequences, and can effectively destroy
a long section of line.

I'm in a similar situation here, with a new tower and LF verticals. The
cables will have to run a long distance over rough land covered with
thorns and sharp stones... and it's usually wet too. For all those
reasons, I am not going to use braided coax, but will try *very very*
hard to locate some surplus hardline.

The advantage of foam-filled hardline is that it's largely immune to
minor damage from the outside. If the plastic jacket is cut or even
removed completely, it doesn't matter at all because you still have
solid copper to keep the water out. And even if you take a slice off the
copper sheath with the mower (BTDT), water will not migrate along the
inside because the closed-cell foam is firmly bonded to the inside
surface of the sheath.

You certainly don't have to buy hardline at new prices - though even
there you might be pleasantly surprised (for example there's an outlet
in VK-land whose prices are very reasonable). Your options will depend
on what's available in ZL, and to find out you may have to tap a few
contacts.

For example, in the UK there's a lot of surplus hardline is coming out
of cellular, broadcast and other VHF/UHF/microwave sites as they are
being upgraded to the next generation. A lot fo this goes straight to
scrap copper, but some gets diverted into the surplus market. Short
lengths appear quite often at radio flea markets ("rallies"), and if you
ask, the guys generally have much longer lengths back home at much lower
prices.

(In the USA they also have aluminium-jacketed cable TV hardline. It
doesn't exist in the UK, but if it's relevant in ZL there are people in
this newsgroup who know about it.)

Crazy as it may sound, the larger sizes of hardline can be cheaper on
the surplus market than the more popular "half-inch" size. The larger
cables are more difficult to transport and less convenient to handle, so
there are fewer buyers and that drives the price down. Even so, 2-3
people can handle the lengths you are considering, and in a fixed
installation you only have to lay it once... and then you really could
say you've reduced the losses "to a minimum".




--
73 from Ian GM3SEK 'In Practice' columnist for RadCom (RSGB)
http://www.ifwtech.co.uk/g3sek

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

I've got some of that which I purchased new, and did some extensive
tests on it with a network analyzer. The loss varies all over the map
depending on how you coil, bend, or flex the cable, and I never saw loss
anywhere near as low as the spec says. A typical value at 400 MHz was
more like 5 - 5.5 dB/100 ft. Glad you're happy with it.

Roy Lewallen, W7EL

Sounds like a flawed test setup. Davis bury flex gets rave reviews (except
for yours) all over the net and on-the -air.
I have over 450ft of the stuff and it's super. I see no effects from
coiling or bending....


Sorry you're having a difficult time...
--

Charlie


"Roy Lewallen" wrote in message
...
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

I've got some of that which I purchased new, and did some extensive tests
on it with a network analyzer. The loss varies all over the map depending
on how you coil, bend, or flex the cable, and I never saw loss anywhere
near as low as the spec says. A typical value at 400 MHz was more like 5 -
5.5 dB/100 ft. Glad you're happy with it.

Roy Lewallen, W7EL

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.

I don't know what you two have going but his "analysis" flies in the face of
every other review and/or comment I have ever read about Davis 9914. As
well as my own experience of low loss and great performance. I have several
bends in my runs of 9914 and no adverse swr.

Have you looked at all the positive user's reviews at eHam about it? Not a
single negative remark..
1. http://www.eham.net/reviews/detail/4515

One might also want to check this link for another endorsement of Davis
BuryFlex 9914
2.
http://lists.contesting.com/archives.../msg00010.html

The again one could just read what is posted at this link at the eHam
Elmer's Forum - all very positive
3. http://www.eham.net/forums/Elmers/38717


I'm not saying Roy is misstating what he saw. I'm saying what he saw
misstates the real quality of this coax.
1. Maybe he got a bad piece
2. Maybe he had a loose connector
3. Maybe he didn't calibrate the network analyzer
4. etc etc etc....NO ONE else I can find dislikes this 9914!!!





--

Charlie


"Wes Stewart" wrote in message
...
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.