RadioBanter - SUPER J-POLE BEATS YAGI BY 1 dB

wrote:

Definitely! You try putting up a VHF
Super J-pole yourself! You are probably
more used to UHF, so 4 bays doesn't scare
you, but at the broadcast band, you will need
some serious help.

I have done both the super J-pole and 4 bays of Dipole
at both UHF and VHF. I've also tested the result with far better
hardware than you have. Beside being a ham I'm also commercial
licensed and have an extensive radio lab.

What brand and model # field strength
meter do you have? Or did you build a
homemade RF rectifying "sniffer" amplified
with an Op-amp? Not saying the later
couldn't be calibrated correctly...

I would love to see what a 4 bay
would do though, but you need serious
bucks to do that, plus alot of manual
labor...

Your kidding right? I figure using both 1" copper water pipe, 1/2"
copper pipe and the various fittings to be cheap. How cheap?
Likely if you spent 50$us you spent too much for your materials.

Yeah, but you need a serious tower
to put 4 bays on, esp. at VHF, which we don't have
the money for.

He doesn't explicitely say brass in
his website, and looking at the picture, it
looks like a cheapie SO-239 made of pot metal.

Looks aren't everything. Also potmetal is not solderable
and his was. I'm normal so I have to test with a file to know
what material the connector is. I can never tell from picture.

He should explicitely state that it
should be made of brass.

Also, solder has VERY little
mechanical strength. Almost none.

It's a bad idea.

It's a bad idea overall. I would
mount it with 4-40 nuts and bolts on
an aluminum plate, and then attach
that to the antenna.

You can but, you are making work thats not required
and you run into dissimilar metal electrolytic corrosion
and plain old rust. Water intrusion is the death of coax
most often. I've worked in marine environments
(salt is corrsive) so I have seen what works. Buy a
decent waterproof connector. I'd say Type N if your
really fussy.

You're correct on this one:

http://www.ssina.com/galvanic/

So then use a brass plate, and
stainless-steel 4-40 bolts and nuts.

But don't rely on solder and the
corner of an SO-239 for strength.

Ah yes, you know all. Some day I"ll post a picture of the antenna
farm both UHF and VHF. Never minding the ones I've given away.
I know what type M and type L 1/2inch copper pipe weigh, do you?

Two bays would use approximately:

6 19" lengths of 1/2" copper (less than 5$)
4 1/2 inch pipe caps (usually less than 20 cents each)
1 10ft length (partial) of 3/4 copper water pipe for the mast
(Runs
about 8$ last I paid for one)
2 1/2 inch tees ( 79 cents)
2 3/4" to 1/2" tees ( $1.49 expensive ones).

This is under 12 pounds and is self supporting to that height.
Plenty light enough for this girl. You could use Aluminum tube
to build this and really cut the weight.

Opps! I meant to say 1" copper. 1/2" copper
is not strong enough for a VHF super J-pole.

Aluminum is not solderable.

The Super J-pole at VHF is big, and
it's worse depending on how high you want
to get it.

Especially for something like the Super J.

Since the super-j doesnt offer the same performance your
claim is specious. As to structural, The super-J often fails
badly at the center insulator and the phasing loop as descrbed often
rarely makes the winter here in the east due to ice, wind and
snow. New England winters are harsh on antennas.

We used a length of Delrin rod for the center
conductor, it's slightly flexible but ultra strong.
Don't use a wooden dowel coated w/epoxy, it will break.

The phasing loop was something like AWG#4
solid copper wire. Hasn't failed for 3 years,
but Ca. is a bit less harsh, indeed!

Slick