In a message dated 4/4/01 6:52:41 AM Pacific Daylight Time,
Hi Ian - -
The silver plated PL-259's are DEFINITELY easier to solder. Texas
Towers (http://www.texastowers.com) used to carry the good Amphenol
PL-259 connectors, and I assume they still do. In short, they're
definitely worth the extra money.
The regular brass PL-259's are very easy to solder if you drill the holes one
drill size larger and then beveling the hole. It exposes clean brass also.
Adding soldering paste makes it even easier. It's faster, takes less heat
and the solder grabs more shield and an idea procedure for pollyfoam coax.
Tinning the shield as has been suggested is a good idea. To keep the overall
diameter small enough to get into the connector after soldering, wrap the
shield with #30 or smaller bare wire. If you get too much solder on it, use
a file. I had an article on all this and other related topics in CQ about
35 years ago.
Type N connectors have a problem outside. I used one on RG-14 coax with a
solid center wire. In cold weather the center solid wire contracted to the
point of disconnecting the pin. If there is only .01" contraction of the pin
after initial shoulder to shoulder contact, the larger diameter shoulders
aren't touching and only the small pin and 4 fingers make contact--potential
trouble at high power.
Another problem with soild wire, just gravity on a vertical run can pull the
center wire down enough to brake the critical shoulder to shoulder contact.
If the 4 fingers pressure contact only carry the RF, higher powers can heat
them up to a point were they tend to lose their pressure and that creates
more heat. I make sure the 4 fingers are flexed tight when first used. I've
inspected them later after a slight pin separation and power level tests to
satisfy me what was going on and they lost their tension to the center. They
will take 5 KW and 10A with pin shoulder contact. I use fine steel wool on
the pin, the pin shoulders, inside the fingers and the shield contact area
inside the connector before use--in all connectors. I even lightly buff the
copper shield that is pressed against this area. In time the rubber
compression ring over the pressure ring begins to dent the coax dialectric
and reduces the pressure on the shield. The compression ring on top can be
retightened. They should be dissasembled from time to time, checked and
cleaned. Look for dents in the coax dialectric, reduced 4 finger pressure
and carbon paths. For this reason type N's don't work well with air
dielectric or polly foam coax.
Henry uses the Type N female output on their 8K rig. Inside the shack there
should be no trouble if the male connector is properly prepared. Just do the
heat test with the fingers on 10M regularly.
PL-259's have a full time and much longer, larger diameter 4 finger contact
area (at least 5 or more times) and the center wire is soldered to a "secured
pin." Cold weather can't move it in and out of the female pin. The shield
is soldered also whereas a type N has a pressure contact for the shield which
lessons in time. I alway clean the pin, inside the female fingers and
retension the fingers if necessary before use. I've never read of anyone
suggestsing this. I started coating the pin and fingers with silicone greese
and it stays clean outside. At legal power levels it works just fine--year
after year. I coat the PL-259 and SO-239 threads with Silicone grease also.
Years later and or in cold weather it comes apart easily, they are both still
clean and show no evidence of heat.
If you run more than 1 KW into Type N's outside use PL-259's. If you use
more than 5 KW into PL-259's in or outside or can have high SWR's, use the
next bigger connector or eliminate the connector with a direct connection
with bolts, soldering lugs and weather proffing It's mandatory to keep the
water out of the PL-259s and I spray acrylic spray around the center pin
insulator a couple of times, let it dry and then RTV silicone rubber. I use
removable shrouds over any exposed coax connections also. On vertical
antennas where the SO-239 is on the bottom pointing down, I remove it and add
a shroud made from an aluminum cat food can 1 1/2" high or 1/2 an aluminum
pop can with the edges bent over to prevent cutting your hand. It keeps the
water from running down the threads into the connector. I also epoxy a 6
inch length of .875 aluminum tubing that I knurled to the PL-259 shell that
allows one to really tighten or remove it with ease in particular in tight
places. No plyers needed.
A very smart Mfg should make a longer knurled outter shell for the Pl-259's.
Any mfg that installs a SO-239 without blown rain protection is guilty of
ruining a lot of coax--after the first rain. Many find water in a lot of
connectors and sometimes in the shack after just one rain and changes of SWR.
With my procedures I don't and I have some good coax 40 years old that has
the same loss year after year when I do my yearly loss tests. One version of
RG-8AU coax has a "non migrating plasticizing" agent in the outer covering
that prevents cracking and water entry claimed for 20 years. I have some
older that this that is still good coax. With regular RG-8 the plasticizing
agent migrates to the center dialectric changing the VP, the color of it, the
loss and allowing cracks in the outside covering. Buy the good stuff,
install connectors properly and protect the connection outside from blown
rain and it will last a long time. My coax investments have been very very
minimal over some 50 years. I started with open wire line and still use one
length of open wire line 60 years later. I never have to check it for loss.
The rain keeps the insulators clean. With the proper tuners like the Johnson
Match Box properly used (and without only opinions of it's capabilities), it
transfers more RF to and from the antenna than coax ever will and at the
least cost. You just have to learn how to use it.
NOTE! With link coupled finals, a link of the right number of turns with a
series Xc, it will match any balanced or unbalanced load from 30-1000 ohms
at the end of any feedline--WITHOUT A TUNER. I still have my old Pr-813's
rig I'll be using with open wire line in the rain and snow with the least
loss. There are simple matching techniques to 450-600 ohms at the antenna
that also allow a flat open wire line (1:1 SWR) and eliminate the need for
certain 1/4 or 1/2 multiples. I do use insulated open wire line now. I got
some great wire from Boeing Surplus.
Over 35 years ago I purchased 4000' of a special 50 ohm Teflon coax for 11
cents a foot from Boeing Surplus. It cost $1.75 then. It is silver plated
and 2 shields. It's thin Teflon tape wrapped, then the 2 shields, some more
thin tape wrap and then a Teflon outer coating--Absolutly Awsome Coax. It
has a .7 VP and about the same loss as pollyfoam. It could take a lot of
over power heat without any damage. I have given some away and still have
2000'. I found at a flea market 250' of $3.75/ft solid Teflon center
dialectric and dual shield new coax I couldn't resist at $1/ft. That's the
first RG8 coax I've purchased in 35 years. I found a large prop pitch motor
in great shape for $50. I've enjoyed thoroughly converting it for higher
speed as I did my first one some 50 years ago I still use without all the
problems and needed Band-Aids many have with rotators today on TT. Ham radio
has a lot of constant maintenance and expenses if you don't select your toys
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