On Jan 11, 1:59*pm, "NoSPAM" wrote:
"Art Unwin" wrote in message

...

"What I use on 7/8 hardline is a copper reducer with a barrel connecter
soldered into one end and then I screw the combination over the hard line..
Now you have an output from the hardline that can fit most things . One
time I filled the copper reducer with dielectric before I inserted the
barrel connecter but could see no difference *using max power. *Certainly a
lot cheaper than Andrews connectors and if the coax route is not ideal it
is easy and inexpensive to add flexible lengths at tight corners, such as
emerging from underground piping. Hardline gets extremely rigid and the
outer insulation is subject to cracking in the winter time which is when I
seem to have to work on things."

Just remember that the aluminum to copper galvanic couple promotes the
corrosion of the aluminum. *Keep the contact areas as dry as possible if
you don't want problems. *I have found that wrapping several layers of
tightly stretched vinyl electrical tape and then spraying the area with
clear Krylon® acrylic varnish does a reasonable job. *But since water vapor
can diffuse through the tape, you will need to check the connection
periodically.

* * 73, *Dr. Barry L. Ornitz *WA4VZQ

All true Then copper reducer matched the copper outside of the
Andrews hardline that I use and it made its own thread as I screwed
it on. I don't believe I soldered that end like I did with the barrel
input tho I often apply a liberal spray of acrylic on those sort of
aplications to prevent the inside copper from going green not that I
have seen that sort of evidence The use of this type of connection at
points of sharp turns on the 1/2 acre
available for the tower away from the residence really works out
inexpensive compared to the Andrews connectors when connecting to
short lengths of Andrews 1/2 flexible coax.
When tussling with long heavy hardline in the winter it invariably
crackes or splits the plastic outer covering exposing the corregated
copper sheathing, so if it has to be moved or replaced it is better if
it is without bends of any sort, I have a long stretch in an
underground pipe which is easily removed as it is without kinks.As
far as the tape goes I find that the 3M professional roles become
subject to perishing so I don't use it any more tho I have plenty of
rolls on hand
Regards
Art

Without actually researching it I suspect the power handling capacity
will be similar to the 1/2" line itself. When a N plug mates with a N
socket it presents the same Z as the line with pretty well the same
diameters. ie the small pin is not carrying the whole load. The RF
losses and subsequent heating will be a function of skin effect of
course. How well the pin is soldered will probably also make a small
difference. Arcover will be an interesting discussion though as there is
an air dielectric where the pieces join..

I guess you could work it out from known resistance of metals, allowing
for skin effect and what will happen first, arcing or melting - all at
50 ohms and a bit of ohms law. Lets face it though you can go and look
at manufacturers websites for this kind of info.

Hardline of larger diameters than an N connector use DIN connectors or
anything else that is "larger". If you are really wanting to know go and
have a look at something like the andrew website for data. You can of
course also reduce to N size using a suitable fitting.

Cheers Bob VK2YQA

ml wrote:
hi

Just wondering a few things

NoSPAM wrote:
"Art Unwin" wrote in message
...

"What I use on 7/8 hardline is a copper reducer with a barrel connecter
soldered into one end and then I screw the combination over the hard
line. Now you have an output from the hardline that can fit most things
. One time I filled the copper reducer with dielectric before I inserted
the barrel connecter but could see no difference using max power.
Certainly a lot cheaper than Andrews connectors and if the coax route is
not ideal it is easy and inexpensive to add flexible lengths at tight
corners, such as emerging from underground piping. Hardline gets
extremely rigid and the outer insulation is subject to cracking in the
winter time which is when I seem to have to work on things."

Just remember that the aluminum to copper galvanic couple promotes the
corrosion of the aluminum. Keep the contact areas as dry as possible if
you don't want problems. I have found that wrapping several layers of
tightly stretched vinyl electrical tape and then spraying the area with
clear Krylon® acrylic varnish does a reasonable job. But since water
vapor can diffuse through the tape, you will need to check the
connection periodically.

73, Dr. Barry L. Ornitz WA4VZQ

Use an elbow to get tight 90s.

http://www.eaa1000.av.org/technicl/c...n/galvanic.htm

Bob Bob wrote:
Without actually researching it I suspect the power handling capacity
will be similar to the 1/2" line itself. When a N plug mates with a N
socket it presents the same Z as the line with pretty well the same
diameters. ie the small pin is not carrying the whole load.

The little pin is only a mating guide for a much larger center conductor.

I like 7/8" "Heliax". EIA connectors.

"Dave" wrote in message
...
NoSPAM wrote:
"Art Unwin" wrote in message
...

"What I use on 7/8 hardline is a copper reducer with a barrel connecter
soldered into one end and then I screw the combination over the hard
line. Now you have an output from the hardline that can fit most things
. One time I filled the copper reducer with dielectric before I inserted
the barrel connecter but could see no difference using max power.
Certainly a lot cheaper than Andrews connectors and if the coax route is
not ideal it is easy and inexpensive to add flexible lengths at tight
corners, such as emerging from underground piping. Hardline gets
extremely rigid and the outer insulation is subject to cracking in the
winter time which is when I seem to have to work on things."

Just to clarify things, the above part is from Art. The following is mine.

Just remember that the aluminum to copper galvanic couple promotes the
corrosion of the aluminum. Keep the contact areas as dry as possible if
you don't want problems. I have found that wrapping several layers of
tightly stretched vinyl electrical tape and then spraying the area with
clear Krylon® acrylic varnish does a reasonable job. But since water
vapor can diffuse through the tape, you will need to check the
connection periodically.

73, Dr. Barry L. Ornitz WA4VZQ

Use an elbow to get tight 90s.

http://www.eaa1000.av.org/technicl/c...n/galvanic.htm

This is a good list because it covers many grades of aluminum and stainless
steel (but unfortunately not the 308 stainless alloy often used in wire and
nuts, bolts, and washers found in hardware stores). I wish it listed the
actual voltages referenced to a standard electrode however. Galvanic
couples of less than a tenth of a volt corrode very slowly and are often
acceptable depending on the application. I have found the following
article useful.
http://www.ocean.udel.edu/seagrant/p...corrosion.html

Also I would like to add that the Krylon sprayed over the vinyl tape is
very important. Being an acrylic, clear Krylon protects the vinyl from
ultraviolet damage.

73, Barry WA4VZQ

On Mon, 12 Jan 2009 21:57:52 -0500, "NoSPAM"
wrote:

Also I would like to add that the Krylon sprayed over the vinyl tape is
very important. Being an acrylic, clear Krylon protects the vinyl from
ultraviolet damage.
73, Barry WA4VZQ

I've been waterproofing RF connectors using 0.5" wide PTFE tape to
embalm the connector. The PTFE will eventually cold flow, forming a
water tight seal. The PTFE also prevents capillary action from
sucking water into the connector through the gaps, such as along the
outer knurling in UHF connectors. On top of that, goes a layer of 3M
Scotch 33+ electrical tape, which is claimed to be UV resistant. The
PTFE tape does the waterproofing. The outer PVC tape just holds
everything in place.

I've done some crude life tests on my roof at 2 year and 5 year
intervals. I found that when unwrapped, the connectors are a shiny
as they were when new.

However, I didn't think that PVC tape was porous and suffers from UV
embrittlement. After about 5 years, the tape does tend to be somewhat
bittle. I'll try some Krylon and see what it does. I'm a bit
concerned about adhesion to the shiny PVC tape and what will happen if
the joint is flexed. I dunno about spraying Krylon when I'm on top of
a tower. I'll let you know in about 5 years.

The no-fun part of semi-rigid coax and Heliax is connector sticker
shock. Connectors are expensive. I've been finding used connectors,
but that creates the problem of finding a replacement crush
(compression) ring. Some vendors supply them seperately, others
don't. I suspect the ones that don't, recognize that non-availability
of these parts creates a market for new connectors. I've had fair
luck using brass plumbing crush rings as a replacement crush ring. Buy
oversized and cut to size with a Dremel cutoff tool or blow saw. Brass
is really NOT a good idea for aluminum jacketed semi-rigid CATV coax,
but it should survive if kept dry.


--
Jeff Liebermann
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558

How much power could it hold at HF and also uhf/vhf
frequencies? Assuming a modern day high quality N connector??

The other thing i pondered is that it seems the don't make
Pl259/so239 connectors for hardline, so what do guys use typically for
higher power DIN?

Good to Gigs at 5kw. I recall a test of Pl259/SO239 connection vs. N found
the PL259/SO239 to fail from overheating due to the internal mismatch with
as little as 500 watts at UHF frequencies.

I don't recall the Maximum at HF, but High SWR is a consideration. Best to
use open wire feeders in that case.

N is a 50 ohm connector, but the PL259/2O239 is a stepped transistion and
isn't even specified for impedance.

"Jeff Liebermann" wrote in message
...
On Mon, 12 Jan 2009 21:57:52 -0500, "NoSPAM"
wrote:

Also I would like to add that the Krylon sprayed over the vinyl tape is
very important. Being an acrylic, clear Krylon protects the vinyl from
ultraviolet damage.
73, Barry WA4VZQ

I've been waterproofing RF connectors using 0.5" wide PTFE tape to
embalm the connector. The PTFE will eventually cold flow, forming a
water tight seal. The PTFE also prevents capillary action from
sucking water into the connector through the gaps, such as along the
outer knurling in UHF connectors. On top of that, goes a layer of 3M
Scotch 33+ electrical tape, which is claimed to be UV resistant. The
PTFE tape does the waterproofing. The outer PVC tape just holds
everything in place.

I've done some crude life tests on my roof at 2 year and 5 year
intervals. I found that when unwrapped, the connectors are a shiny
as they were when new.

However, I didn't think that PVC tape was porous and suffers from UV
embrittlement. After about 5 years, the tape does tend to be somewhat
bittle. I'll try some Krylon and see what it does. I'm a bit
concerned about adhesion to the shiny PVC tape and what will happen if
the joint is flexed. I dunno about spraying Krylon when I'm on top of
a tower. I'll let you know in about 5 years.

The issue is a little more complicated than simple UV resistance and
porosity. To begin with, pure PVC has a very poor UV resistance. But more
importantly, it is brittle and it needs a plasticizer to make it flexible.
The most common plasticizer is DOP [dioctal phthalate, or more correctly
2-ethylhexyl phthalate]. but this can leach out of the PVC leaving it stiff
and more brittle.. To achieve better low temperature flexibility, DOA
{2-ethylhexyl adipate} is often used. Vinyl tape has to be very flexible
and stretchy even at low temperatures, so high levels of plasticizers are
needed. DOA is usually used, either alone or in combination with DOP. DOA
tends to leach out faster than DOP. It also has poorer UV resistance than
DOP which is poor to start with. There are far better performing
plasticizers than either of these (made by reacting adipic or phthalic acid
with polyols), but while they offer superior UV resistance and leach out
much more slowly, they are rather expensive. Loading the PVC with carbon
black, an excellent absorber of ultraviolet (and visible) light, helps too,
but the amount of carbon black that can be used on an electrical tape is
limited by the need for good dielectric strength. Spraying the tape with
Krylon® acrylic paints provides both UV resistance and a slowing of the
loss of plasticizer.

I would not worry about the PTFE (Teflont®) tape. While very resistant to
liquid water, water vapor can pass through the tape easily and condense on
cold metal parts of the connector. PTFE tape is porous, but the surface
tension of water prevents it from passing through the pores. {Water vapor,
too, is a smaller molecule than oxygen or nitrogen.} Several layers of
electrical tape, wound in opposite directions, and sprayed with Krylon
survived at least 15 years in one of my outdoor applications, and when
removed, the coaxial connectors were shiny too.

In case anyone is wondering about my expertise here, I worked in the
research Laboratories of Eastman Chemical Company, who made a number of
plasticizers, and W. L. Gore & Associates, who started by making PTFE tape.
The breathability properties of Gore-Tex while still shedding water are a
result of controlled pore sizes in PTFE.

73, Dr. Barry L. Ornitz WA4VZQ

JB wrote:
How much power could it hold at HF and also uhf/vhf
frequencies? Assuming a modern day high quality N connector??

The other thing i pondered is that it seems the don't make
Pl259/so239 connectors for hardline, so what do guys use typically for
higher power DIN?

Good to Gigs at 5kw. I recall a test of Pl259/SO239 connection vs. N found
the PL259/SO239 to fail from overheating due to the internal mismatch with
as little as 500 watts at UHF frequencies.

I don't recall the Maximum at HF, but High SWR is a consideration. Best to
use open wire feeders in that case.

N is a 50 ohm connector, but the PL259/2O239 is a stepped transistion and
isn't even specified for impedance.



JB sez "N is a 50 ohm connector, but the PL259/2O239 is a stepped
transistion and isn't even specified for impedance."

Actually, think you will find that N connectors, as well as BNC
connectors come in Several Impedences! (Not one size fits all).

Had surplus ones with center pins fit 90 ohm, and 75 ohm (no go on 50
ohm coax)! Be sure to check connector specs! Jim NN7K

On Tue, 13 Jan 2009 22:34:48 -0500, "NoSPAM"
wrote:

The breathability properties of Gore-Tex while still shedding water are a
result of controlled pore sizes in PTFE.

Hi Barry,

How come my Gore-tex jacket (20 years old?) leaks like a sieve?

73's
Richard Clark, KB7QHC