Over the years I have built several Quadrafiliar antennas for 137.5 Mhz
polar orbiting weather satellite photos. I have the dimensions pretty
well refined to get horizon to horizon reception but they have all been
copper tube on a PVC pipe. I have some 3/8" stainless tube left from
the watermaker project and thought I might use it and a piece of FRP
tube to make one that would hold up at sea. I have a couple of
questions about changing over to stainless but don't know where to ask
them.

There is plenty of info on the web but I can't seem to find a newsgroup
or forum to ask questions. Anyone else here dabble in quadrafiliars?


--
Glenn Ashmore

I'm building a 45' cutter in strip/composite. Watch my progress (or lack
there of) at: http://www.rutuonline.com
Shameless Commercial Division: http://www.spade-anchor-us.com

Hi Glenn,

I have a quadrafilar I use on 137.5 for satellites. It is built of SS flat
stock
rather than tube, but it works great. I have a preamp mounted near the base
of the antenna as well. I'd be glad to send you some pics and dimensions.
I doubt if there makes a difference using SS vs copper.

Doug, k3qt
s/v Callista

"Glenn Ashmore" wrote in message
news:C5Csb.235$0K4.15@lakeread04...
Over the years I have built several Quadrafiliar antennas for 137.5 Mhz
polar orbiting weather satellite photos. I have the dimensions pretty
well refined to get horizon to horizon reception but they have all been
copper tube on a PVC pipe. I have some 3/8" stainless tube left from
the watermaker project and thought I might use it and a piece of FRP
tube to make one that would hold up at sea. I have a couple of
questions about changing over to stainless but don't know where to ask
them.

There is plenty of info on the web but I can't seem to find a newsgroup
or forum to ask questions. Anyone else here dabble in quadrafiliars?


--
Glenn Ashmore

I'm building a 45' cutter in strip/composite. Watch my progress (or lack
there of) at: http://www.rutuonline.com
Shameless Commercial Division: http://www.spade-anchor-us.com

We had a QH for weather satellites on Swee****er and I might do the same on
Fintry -- as a practical matter it's a fun toy, but you need other weather
information as well.

Why not just use copper -- the conductivity of stainless is only 2% of
copper, so there are surely some issues there?



--
Jim Woodward
www.mvFintry.com


..
"Glenn Ashmore" wrote in message
news:C5Csb.235$0K4.15@lakeread04...
Over the years I have built several Quadrafiliar antennas for 137.5 Mhz
polar orbiting weather satellite photos. I have the dimensions pretty
well refined to get horizon to horizon reception but they have all been
copper tube on a PVC pipe. I have some 3/8" stainless tube left from
the watermaker project and thought I might use it and a piece of FRP
tube to make one that would hold up at sea. I have a couple of
questions about changing over to stainless but don't know where to ask
them.

There is plenty of info on the web but I can't seem to find a newsgroup
or forum to ask questions. Anyone else here dabble in quadrafiliars?


--
Glenn Ashmore

I'm building a 45' cutter in strip/composite. Watch my progress (or lack
there of) at: http://www.rutuonline.com
Shameless Commercial Division: http://www.spade-anchor-us.com

Jim Woodward wrote:
We had a QH for weather satellites on Swee****er and I might do the
same on Fintry -- as a practical matter it's a fun toy, but you need
other weather information as well.

I like to put the picture beside the current surface analysis to get a
feel for what is happening. A sequence of 3 or 4 passes really shows
the movement of a weather system.

Why not just use copper -- the conductivity of stainless is only 2%
of copper, so there are surely some issues there?

Mainly for apearance. The QFH will mount on the stern rail at eye
level. My copper versions are hard copper tube and elbows. Soft copper
is to soft to stand up to a careless hand or a boarding wave. The
stainless tube looks less like a plumber's nightmare and will not turn
green.

The resistance of the stainless tube is the thing that worries me. The
balun design I came up with balances 1/2" copper tube to 50 ohms almost
perfectly but changing the diameter to 3/8" stainless is going to change
the impedance. I just don't know how much and in which direction.

--
Glenn Ashmore

I'm building a 45' cutter in strip/composite. Watch my progress (or lack
there of) at: http://www.rutuonline.com
Shameless Commercial Division: http://www.spade-anchor-us.com

For me it is more of a toy than a practical tool. I'm not very good
at interpreting the images. My software does false coloring of
sea surface and cloud tops so that provides some useful info. I
haven;t noticed any real difference between my original turnstile
antenna, homebrew copper/PVC Quadrifilar antenna, and my current
commercially made stainless steel quadrifilar antenna. Maybe skin-effect
has something to do with it since to os RF.

Doug
s/v Callista

"Jim Woodward" jameslwoodward at attbi dot com wrote in message
...
We had a QH for weather satellites on Swee****er and I might do the same
on
Fintry -- as a practical matter it's a fun toy, but you need other weather
information as well.

Why not just use copper -- the conductivity of stainless is only 2% of
copper, so there are surely some issues there?



--
Jim Woodward
www.mvFintry.com


.
"Glenn Ashmore" wrote in message
news:C5Csb.235$0K4.15@lakeread04...
Over the years I have built several Quadrafiliar antennas for 137.5 Mhz
polar orbiting weather satellite photos. I have the dimensions pretty
well refined to get horizon to horizon reception but they have all been
copper tube on a PVC pipe. I have some 3/8" stainless tube left from
the watermaker project and thought I might use it and a piece of FRP
tube to make one that would hold up at sea. I have a couple of
questions about changing over to stainless but don't know where to ask
them.

There is plenty of info on the web but I can't seem to find a newsgroup
or forum to ask questions. Anyone else here dabble in quadrafiliars?


--
Glenn Ashmore

I'm building a 45' cutter in strip/composite. Watch my progress (or lack
there of) at: http://www.rutuonline.com
Shameless Commercial Division: http://www.spade-anchor-us.com

I understand the issues, but not how to figure them out -- less surface
area, higher resistance material -- I'd guess it would increase the
impedance, but that's not even a sophisticated wild ass guess.

How about just painting the copper? I would guess you've got one or two
things to do with your time more important than redesigning an antenna for
better appearance.

Have you considered putting an arch back there -- two tubes up, over, and
down? Good for this, GPS, VHF emergency antenna, SSB emergency antenna,
maybe radar (ours was on a pole at one end of the arch), Inmarsat C, etc.
etc. etc. Could also anchor the bimini.

As for the utility of the photos, sometimes they're helpful, but often
not -- for example, today the photo doesn't show anything interesting, but
the isobars are so close we've got 50 knot gusts forecast in Mass Bay.

--
Jim Woodward
www.mvFintry.com


..


Jim Woodward wrote:
We had a QH for weather satellites on Swee****er and I might do the
same on Fintry -- as a practical matter it's a fun toy, but you need
other weather information as well.

I like to put the picture beside the current surface analysis to get a
feel for what is happening. A sequence of 3 or 4 passes really shows
the movement of a weather system.

Why not just use copper -- the conductivity of stainless is only 2%
of copper, so there are surely some issues there?

Mainly for apearance. The QFH will mount on the stern rail at eye
level. My copper versions are hard copper tube and elbows. Soft copper
is to soft to stand up to a careless hand or a boarding wave. The
stainless tube looks less like a plumber's nightmare and will not turn
green.

The resistance of the stainless tube is the thing that worries me. The
balun design I came up with balances 1/2" copper tube to 50 ohms almost
perfectly but changing the diameter to 3/8" stainless is going to change
the impedance. I just don't know how much and in which direction.

--
Glenn Ashmore

I'm building a 45' cutter in strip/composite. Watch my progress (or lack
there of) at: http://www.rutuonline.com
Shameless Commercial Division: http://www.spade-anchor-us.com

What is really nice is the capability to capture multiple passes which are
automatically georeferenced and put them into into a sequence that can
then be animated. Same thing applies to WX FAXs although they have
to me georeferenced manually. Really allows you to see what is going
on. What would be nice is to be able to overlay WX FAX onto the
satellite image. Maybe in a future release.

Doug

"Glenn Ashmore" wrote in message
news:_bMsb.554$0K4.386@lakeread04...


Jim Woodward wrote:
We had a QH for weather satellites on Swee****er and I might do the
same on Fintry -- as a practical matter it's a fun toy, but you need
other weather information as well.

I like to put the picture beside the current surface analysis to get a
feel for what is happening. A sequence of 3 or 4 passes really shows
the movement of a weather system.

Why not just use copper -- the conductivity of stainless is only 2%
of copper, so there are surely some issues there?

Mainly for apearance. The QFH will mount on the stern rail at eye
level. My copper versions are hard copper tube and elbows. Soft copper
is to soft to stand up to a careless hand or a boarding wave. The
stainless tube looks less like a plumber's nightmare and will not turn
green.

The resistance of the stainless tube is the thing that worries me. The
balun design I came up with balances 1/2" copper tube to 50 ohms almost
perfectly but changing the diameter to 3/8" stainless is going to change
the impedance. I just don't know how much and in which direction.

--
Glenn Ashmore

I'm building a 45' cutter in strip/composite. Watch my progress (or lack
there of) at: http://www.rutuonline.com
Shameless Commercial Division: http://www.spade-anchor-us.com

Glenn, have you ever tried alarm window foil in a turnstyle pattern
taped to a fiberglass deck? Radio Shack has the foil tape and
connecting terminals. Works as good taped to the inside of the deck
in the cabin as it does outside taped to the top of it.

Of course, it doesn't look as neat as an Andrews radome, but clutters
the boat a lot less...(c;


On Thu, 13 Nov 2003 08:58:12 -0500, Glenn Ashmore
wrote:



Jim Woodward wrote:
We had a QH for weather satellites on Swee****er and I might do the
same on Fintry -- as a practical matter it's a fun toy, but you need
other weather information as well.

I like to put the picture beside the current surface analysis to get a
feel for what is happening. A sequence of 3 or 4 passes really shows
the movement of a weather system.

Why not just use copper -- the conductivity of stainless is only 2%
of copper, so there are surely some issues there?

Mainly for apearance. The QFH will mount on the stern rail at eye
level. My copper versions are hard copper tube and elbows. Soft copper
is to soft to stand up to a careless hand or a boarding wave. The
stainless tube looks less like a plumber's nightmare and will not turn
green.

The resistance of the stainless tube is the thing that worries me. The
balun design I came up with balances 1/2" copper tube to 50 ohms almost
perfectly but changing the diameter to 3/8" stainless is going to change
the impedance. I just don't know how much and in which direction.

--
Glenn Ashmore

I'm building a 45' cutter in strip/composite. Watch my progress (or lack
there of) at: http://www.rutuonline.com
Shameless Commercial Division: http://www.spade-anchor-us.com



Larry W4CSC

"Very funny, Scotty! Now, BEAM ME MY CLOTHES! KIRK OUT!"

Might work. Setting up a balun to work with it might be tricky
though.

Doug

"Larry W4CSC" wrote in message
...
Glenn, have you ever tried alarm window foil in a turnstyle pattern
taped to a fiberglass deck? Radio Shack has the foil tape and
connecting terminals. Works as good taped to the inside of the deck
in the cabin as it does outside taped to the top of it.

Of course, it doesn't look as neat as an Andrews radome, but clutters
the boat a lot less...(c;


On Thu, 13 Nov 2003 08:58:12 -0500, Glenn Ashmore
wrote:



Jim Woodward wrote:
We had a QH for weather satellites on Swee****er and I might do the
same on Fintry -- as a practical matter it's a fun toy, but you need
other weather information as well.

I like to put the picture beside the current surface analysis to get a
feel for what is happening. A sequence of 3 or 4 passes really shows
the movement of a weather system.

Why not just use copper -- the conductivity of stainless is only 2%
of copper, so there are surely some issues there?

Mainly for apearance. The QFH will mount on the stern rail at eye
level. My copper versions are hard copper tube and elbows. Soft copper
is to soft to stand up to a careless hand or a boarding wave. The
stainless tube looks less like a plumber's nightmare and will not turn
green.

The resistance of the stainless tube is the thing that worries me. The
balun design I came up with balances 1/2" copper tube to 50 ohms almost
perfectly but changing the diameter to 3/8" stainless is going to change
the impedance. I just don't know how much and in which direction.

--
Glenn Ashmore

I'm building a 45' cutter in strip/composite. Watch my progress (or lack
there of) at: http://www.rutuonline.com
Shameless Commercial Division: http://www.spade-anchor-us.com



Larry W4CSC

"Very funny, Scotty! Now, BEAM ME MY CLOTHES! KIRK OUT!"