"Ed Huntress" wrote in message
...
On Sun, 7 Feb 2016 12:11:35 -0500, "Jim Wilkins"
wrote:
"Larry Jaques" wrote in message
. ..
On Sat, 6 Feb 2016 23:21:08 -0500, "Jim Wilkins"
wrote:
"Larry Jaques" wrote in
message
m...
On Sat, 6 Feb 2016 15:38:04 -0500, "Jim Wilkins"
wrote:
"Ignoramus14059" wrote in
message ...
On 2016-02-06, Jim Wilkins wrote:
I often look at all that stuff, and I find extreme ingenuity
with
which people overcame limitations of their current
technologies,
it
is
fascinating.
i
Tbe one that impresses me most is the old analog telephone which
does
everything over two wires without active electronics, only one
very
clever transformer, speaker and carbon mike. I couldn't quickly
find
a
circuit description and should return to fixing my fallen TV
antenna
that had me abseiling down the snow-covered roof.
It's a good thing you were strung up.
I hadn't practiced a Dulfersitz in decades.
Abseiling I knew, after having to look it up last year when my
niece
and new nephew went to Gnu Zealand for spelunking and Middle
Earthing.
They had a blast. I had to look up Dulfersitz, and it definitely
does
not look like something I'd try in anything but an emergency. If
you
slipped, you'd likely lose control of the rope and fall.
P.S: Doesn't anyone say "rappelling" any more?
Rappeler is French for recall, as in recalling the doubled rope from
the bottom. Maybe French has lost its cachet of exclusiveness to
German? Have you seen any French competition to Audi, BMW or
Mercedes
recently?
Wednesday the forecast was for 10-20MPH winds, not the howling
gale
that blew the TV antenna down. Thursday I replaced the bent mast
section, then Friday the predicted few inches of light snow clung
to
the guy lines and pulled it down again, and this time it smacked
the
roof HARD right over me.
Time for a new mast system, wot? Better yet, Repent!, and TV no
more.
I'm going on 11 years without it now. Netflix and Redbox give me
the
movie fixes I need, but I haven't suffered through brainless
broadcast
TV or the massively stupid and numerous commercials for over a
decade.
The only commercials I actively seek are those for the Stupor
Bowl,
and even then, at millions a pop, they put some stupid one on.
The
money spent on sports and commercials each year would be enough,
in
one single year, to -feed- and -house- the homeless and hungry
poor
in
America (even those who don't deserve it), and probably a few
dozen
other countries. Too bad so few people have this perspective.
(Sorry, it just slipped out.)
TVs do have an OFF switch, you know, for those of us with the self
control to use it. Mine is mainly my best source of up-to-date local
news and weather. Until I decide how to reengineer the insulators in
a
material with different properties I can use Boston weather
forecasts,
that antenna wasn't damaged.
I used to tell TV haters that they were missing good material on PBS
but it no longer has much that interests me.
There are 5 oak insulator blanks sitting on the milling machine to
be
completed tomorrow. I made one to replace the first fall's damage,
boiled it in wax to drive out the water and seal it, and didn't
lose
any signal strength from it.
Whuffo? Doesn't good cable preclude the need? Or are you
insulating
the mast from something? I don't recall having heard about this.
Or
are you the poor sod who was blessed with an overly lightningized
environment? If so, would oak insulators even help? A million
volt,
million amp spark which jumps thousands of feet of air in an
instant
is pretty hard to protect from, innit? Just sayin...
These insulators support the two sections of the dipoles without
letting them short to each other or the metal supporting structure.
The radio waves picked up from the air appear as a tiny voltage
between the inner ends.
http://www.hottconsultants.com/pdf_files/dipoles-1.pdf
-jsw
I haven't heard of anyone using wood insulators boiled in paraffin
since I had my first ham radio license, in 1960. You do drag out
some
old technology, Jim. g
I'm sure it worked well. In fact, I had a ladder line feeding my
first
40m dipole with paraffin-soaked wooden insulators, but that was a
gift
from an old ham who was helping me get started. I never measured its
performance but I worked Australia and Norway with 50 W using that
antenna.
Anyway, if you're looking for modern materials that are excellent
insultators, have low dielectric, and stand up to sunlight, you have
a
lot to choose from. A QRP fanatic/friend I know, who is a plastics
engineer, uses FEP. I don't know where you get it, but it's supposed
to be good stuff.
My old end-fed wire (which is now down) has ceramic egg insulators,
which I've use for most of the past 50 years.
--
Ed Huntress
KC2NZT
The two local station I use that antenna for are near 200 MHz, and I
haven't found loss tangent data on thoroughly dried wood above 50 MHz.
Immersing wood in 280F molten wax certainly forces a lot of water out
the end grain, and seals the wood to keep it out. I made a waxed
pulley from scrap casket mahogany that lasted unchanged outdoors for
many years until a glue joint failed.
Ned Simmons sent me some cutoff ends of 1" Teflon rod to try. I
couldn't copy the existing insulators while they were 50' up in the
air, but now I can experiment with either machining the rod or
compressing it into a hot mold. It doesn't matter if the cycle time is
4 hours per part or if I have to weigh out the quantity of plastic
that will just fill the mold.
-jsw