Today's Message Index:
----------------------
1. 02:40 AM - expanded horizons (Glen Matejcek)
2. 07:18 AM - Antennae materials (Eric M. Jones)
3. 08:39 AM - Re: Antennae materials (Robert L. Nuckolls, III)
4. 09:11 AM - Re: Uneven dipole elements (Robert L. Nuckolls, III)
5. 10:46 AM - Re: Uneven dipole elements (Mike Wynn)
6. 11:14 AM - Re: Uneven dipole elements (Dave Saylor)
7. 11:17 AM - Re: Uneven dipole elements (Robert L. Nuckolls, III)
8. 11:42 AM - Re: Uneven dipole elements (Robert L. Nuckolls, III)
9. 02:30 PM - Re: HID lighting observations (Brantel)
10. 03:58 PM - Re: Re SWR Meter? (Noel Loveys)
11. 04:19 PM - LED WigWag with B&C SSF-1 (Michael Ashura)
12. 04:48 PM - Re: Uneven dipole elements (Noel Loveys)
13. 06:48 PM - Correction (Michael Ashura)
14. 09:37 PM - Re: Uneven dipole elements (Robert L. Nuckolls, III)
15. 11:35 PM - Re: Uneven dipole elements (Dave Saylor)
Message 1
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Subject: | expanded horizons |
Hi Bob-
Just in case you're not familiar, the EAA has a series of shorts available online
called Hints for Homebuilders. It is quite a collection of how-to's. I don't
know what the implications for intellectual property or aero politics would
be if one participated there, but they certainly have the venue aspect nailed.
FYI-
Glen Matejcek
Message 2
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Subject: | Antennae materials |
First a word on the performance of electronic materials:
We all know that materials have a DC bulk resistivity that is a measure of how
they transfer electrons through the material. But for high frequency applications
another characteristic is critical: Most dielectric materials are made of
molecules with polar configurations that is, their constituent molecules have
shapes where their atoms tend to be non-symmetrically attached. Thus these molecules
will twist to try to align with electromagnetic fields imposed on them.
A microwave oven is a good example. Water is somewhat bipolar, and an imposed electromagnetic
wave causes the water molecule to change its orientation every
cycle, thus producing mechanical heating--and cooking your food. If you were trying
to build a PCB for 2.45 GHz, the common household microwave-oven frequency,
water, or anything that absorbed water, or anything that was somewhat molecularly-similar
to water would be a poor choice.
The materials needed for antennas and PCBs have many structural and environmental
constraints (strong enough, reasonably high temperature, no asbestos, waterproof,
flame retardant, machinable, etc.) but are critically restrained by the
requirement that the molecules making up the material not oscillate much at the
frequencies to be used. The molecular shape (to over-simplify), and how well
they are locked into the material is the key. This usually limits the commercial
material selection to thermosetting materials like phenolic and Bakelite
or high-pressure thermosetting resins like epoxies.
When faced with building PCB or antenna supports or other high-frequency electronic
parts, many people rely on some very old and august information. Much of
this was compiled over half-a-century ago, and while one can appreciate its particular
no-nonsense clarity, it misses all the recent advances.
This has many negative affects: Poor material selections drive production prices
up and structural dependability down. Time is wasted pursuing arcane magic materials
invented decades ago and now largely unobtainablewhile simple to use,
cheap and easily-sourced materials are available.
See:
Good History! Tables of Dielectric Materials. Wright Laboratories, Feb 1944 http://www.dtic.mil/cgi-bin/GetTRDoc?AD=ADA288986
Here is a good and much more recent description of the choice of materials.
http://www.speedingedge.com/PDF-Files/tutorial.pdf
The recent discussion of searches for micarta, paper phenolic and Bakelite is a
case in point. While these materials had their day, modern designs are almost
entirely PCB materials like FR-4, (which almost universally replaced G10 and
most other G- and FR- materials).
So thats the story: Abandon your search for half-century old materials and use
FR-4 glass epoxy. MSC Hardware is a great source for machining stock, but if you
have a PCB fabricating house nearby, ask to grab some from their dumpster (thats
how I do it).
--------
Eric M. Jones
www.PerihelionDesign.com
113 Brentwood Drive
Southbridge, MA 01550
(508) 764-2072
emjones(at)charter.net
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=369609#369609
Message 3
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Subject: | Re: Antennae materials |
>
>So thats the story: Abandon your search for
>half-century old materials and use FR-4 glass
>epoxy. MSC Hardware is a great source for
>machining stock, but if you have a PCB
>fabricating house nearby, ask to grab some from
>their dumpster (thats how I do it).
Well stated but with one caveat. The dielectric constant
for FR-4 versus the filled phenolic may be different.
Probably is . . . but haven't had time to research/test
it. This was the driving thought for getting my hands
on a production example of the subject antenna. Direct
measurement of the gamma-match capacitor fabricated
from production parts yielded a value of 34 pF.
This becomes the benchmark for substitution of materials.
The choices are many but in this instance, they are not
an apples-for-apples substitution. I'm considering the
use of 1/32" copper clad for fabrication of a similar
antenna. The copper lends itself to soldered joints
(gas tight for centuries). The double-sided cladding
offers an opportunity to craft the gamma-match strut
from a single piece of FR-4 with copper bonded to both
sides.
Just another interesting project for the future . . .
perhaps we can get to it before VOR goes the way
of A-N Range stations.
Bob . . .
Message 4
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Subject: | Re: Uneven dipole elements |
At 12:39 AM 3/30/2012, you wrote:
>>Can't you splice it back on?<<
Short answer--no.
We had to lop the tip off a vertical stab to make
room for more rudder horn on a Lancair ES. I
didn't stop to think about an internal antenna. I shoulda.
If the structure needed to be shortened . . . and the
antenna is embedded in structure, would it have made
any difference?
On further inspection, the antenna seems to have
three elements. Two run up each side of the
Vstab trailing edge, aft of the stern
post. They're embedded in the fiberglass and are nearly equal in length.
Do you have any documentation on how this antenna was
installed? I'm having trouble putting my gray-matter
around your description.
The element that was cut off is 8" forward of the
Vstab trailing edge. I can't tell exactly how
the three segments are connected. The aft-most
two elements are visible through the fiberglass
when the rudder is removed. I can see a lot of
the cut element using a boroscope inside the Vstab.
Would I hurt the radio to try transmitting and
receiving? If this isn't easy to fix, we have
the option of installing a belly-mounted
replacement antenna using a spray-on ground plane.
Get an SWR meter and see how bad the crippled antenna
really is.
Spray-on ground planes are like using Kleenex for
wing fabric. Metallic radials on inside of skin
is both the best and least we know how to do.
Bob . . .
Message 5
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Subject: | Re: Uneven dipole elements |
Bob,
This ant design sounds like the one I spoke about. BTW: I found the
diagrams and factory instructions, finally. Will scan and send today.
Maybe it will help Dave S. with decision. GL!
Mike Wynn
Moab, UT
**********
----- Original Message -----
From: Dave Saylor
To: aeroelectric-list@matronics.com
Sent: Thursday, March 29, 2012 11:39 PM
Subject: Re: AeroElectric-List: Uneven dipole elements
>>Can't you splice it back on?<<
Short answer--no.
We had to lop the tip off a vertical stab to make room for more rudder
horn on a Lancair ES.=C2 I didn't stop to think about an internal
antenna.=C2 I shoulda.
On further inspection, the antenna seems to have three elements.=C2
Two run up each side of the Vstab trailing edge, aft of the stern
post.=C2 They're embedded in the fiberglass and are nearly equal in
length.
The element that was cut off is 8" forward of the Vstab trailing
edge.=C2 I can't tell exactly how the three segments are connected.=C2
The aft-most two elements are visible through the fiberglass when the
rudder is removed.=C2 I can see a lot of the cut element using a
boroscope inside the Vstab.
Would I hurt the radio to try transmitting and receiving?=C2 If this
isn't easy to fix, we have the option of installing a belly-mounted
replacement antenna using a spray-on ground plane.
--Dave Saylor
On Thu, Mar 29, 2012 at 7:45 PM, Robert L. Nuckolls, III
<nuckolls.bob@aeroelectric.com> wrote:
<nuckolls.bob@aeroelectric.com>
At 05:30 PM 3/29/2012, you wrote:
<dave.saylor.aircrafters@gmail.com>
Bob,
We managed to chop about 3 inches off the end of a dipole comm
antenna. =C2 Would that have any appreciable effect on
performance?
=C2 Sure, but if I were to give you a 'number' . . . it wouldn't
=C2 have much practical meaning. Is this an internal antenna?
=C2 Can't you splice it back on?
=C2 Bob . . .
-
ric-List"
target="_blank">http://www.matronics.com/Navigator?AeroElectric-List
MS -
k">http://forums.matronics.com
e -
=C2 =C2 =C2 =C2 =C2 -Matt Dralle, List Admin.
t="_blank">http://www.matronics.com/contribution
Message 6
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Subject: | Re: Uneven dipole elements |
Thanks! I'd like to know what this antenna looks like.
Off topic: It's on an as-yet unfinished Lancair ES with a 15-year old
panel. It had a huge FMS-type display (that won't boot up) called a
Avro-Tec FMP 300.
The antenna in question is switched by a Comant gizmo between two comms.
We stumbled back-asswards into an antenna engineer who works for L3 across
the street from us. His hobby is helping ham operators build antennas, and
he should be here Saturday to do a "sweep"...whatever that is.
--Dave Saylor
On Fri, Mar 30, 2012 at 10:45 AM, Mike Wynn <wynaire@citlink.net> wrote:
> **
> Bob,
> This ant design sounds like the one I spoke about. BTW: I found the
> diagrams and factory instructions, finally. Will scan and send today. May
be
> it will help Dave S. with decision. GL!
> Mike Wynn
> Moab, UT
> **********
>
> ----- Original Message -----
> *From:* Dave Saylor <dave.saylor.aircrafters@gmail.com>
> *To:* aeroelectric-list@matronics.com
> *Sent:* Thursday, March 29, 2012 11:39 PM
> *Subject:* Re: AeroElectric-List: Uneven dipole elements
>
> >>Can't you splice it back on?<<
>
> Short answer--no.
>
> We had to lop the tip off a vertical stab to make room for more rudder
> horn on a Lancair ES.=C3=82 I didn't stop to think about an internal ant
enna.=C3=82
> I shoulda.
>
> On further inspection, the antenna seems to have three elements.=C3=82 T
wo run
> up each side of the Vstab trailing edge, aft of the stern post.=C3=82 Th
ey're
> embedded in the fiberglass and are nearly equal in length.
>
> The element that was cut off is 8" forward of the Vstab trailing edge.=C3
=82 I
> can't tell exactly how the three segments are connected.=C3=82 The aft-m
ost two
> elements are visible through the fiberglass when the rudder is removed.
=C3=82 I
> can see a lot of the cut element using a boroscope inside the Vstab.
>
> Would I hurt the radio to try transmitting and receiving?=C3=82 If this
isn't
> easy to fix, we have the option of installing a belly-mounted replacement
> antenna using a spray-on ground plane.
>
> --Dave Saylor
>
>
> On Thu, Mar 29, 2012 at 7:45 PM, Robert L. Nuckolls, III <
> nuckolls.bob@aeroelectric.com> wrote:
>
>> nuckolls.bob@aeroelectric.com**>
>>
>>
>> At 05:30 PM 3/29/2012, you wrote:
>>
>>> dave.saylor.aircrafters@**gmail.com <dave.saylor.aircrafters@gmail.com>
>
>>>
>>> Bob,
>>>
>>> We managed to chop about 3 inches off the end of a dipole comm
>>> antenna. =C3=82 Would that have any appreciable effect on performance?
>>>
>>
>> =C3=82 Sure, but if I were to give you a 'number' . . . it wouldn't
>> =C3=82 have much practical meaning. Is this an internal antenna?
>> =C3=82 Can't you splice it back on?
>>
>>
>> =C3=82 Bob . . .
>>
>> ====**===================
===========**=
>> -
>> ric-List" target="_blank">http://www.matronics.com/**
>> Navigator?AeroElectric-List
>> ====**===================
===========**=
>> MS -
>> k">http://forums.matronics.com
>> ====**=====**=
>> e -
>> =C3=82 =C3=82 =C3=82 =C3=82 =C3=82 -Matt Dralle, List Admin.
>> t="_blank">http://www.matronics.com/**contribution
>> ====**===================
===========**=
>>
>>
>>
>>
> *
>
> href="http://www.matronics.com/Navigator?AeroElectric-List">http://www.
matronics.com/Navigator?AeroElectric-List
> href="http://forums.matronics.com">http://forums.matronics.com
> href="http://www.matronics.com/contribution">http://www.matronics.com/c
*
>
> *
>
===========
===========
===========
===========
> *
>
>
Message 7
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Subject: | Re: Uneven dipole elements |
At 12:45 PM 3/30/2012, you wrote:
>Bob,
>This ant design sounds like the one I spoke about. BTW: I found the
>diagrams and factory instructions, finally. Will scan and send
>today. Maybe it will help Dave S. with decision. GL!
>Mike Wynn
>Moab, UT
Thank you! I'll post it to the reference documents
folder on the website too.
Bob . . .
Message 8
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Subject: | Re: Uneven dipole elements |
At 01:12 PM 3/30/2012, you wrote:
>Thanks!=C2 I'd like to know what this antenna looks like.
>
>Off topic:=C2 It's on an as-yet unfinished
>Lancair ES with a 15-year old panel.=C2 It had a
>huge FMS-type display (that won't boot up) called a Avro-Tec FMP 300.
>
>The antenna in question is switched by a Comant gizmo between two comms.
>
>We stumbled back-asswards into an antenna
>engineer who works for L3 across the street from
>us.=C2 His hobby is helping ham operators build
>antennas, and he should be here Saturday to do a "sweep"...whatever that
is.
A 'sweep' is done with a supper-whizzy network analyzer
usually fitted the a sweep generator and graphical display
for the output of the analyzer. You get pictures like this
in seconds
Emacs!
Us poor guys use an SWR meter and variable frequency
energy source to step through the frequencies of
interest and record data. That data is then
massaged like our algebra teachers taught us. After
you've done it a few dozen times, any notions of it
being a 'sweep' are replace the realization that
it's really a 'plod'.
It will be interesting to see what he finds. Take
pictures of his test setup and data to share with
us if you can.
Bob . . .
Message 9
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Subject: | Re: HID lighting observations |
The newer HID ballast have circuitry to limit the inrush current.
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=369637#369637
Message 10
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I've used MFJ for years with no problems... HF and VHF.
Noel
From: owner-aeroelectric-list-server@matronics.com
[mailto:owner-aeroelectric-list-server@matronics.com] On Behalf Of Harley
Sent: March 29, 2012 11:39 AM
Subject: Re: AeroElectric-List: Re SWR Meter?
Paul...
Yep, still available...(a little more than you probably paid for it):
www.mfjenterprises.com/Product.php?productid=MFJ-862
Harley
I use my meter to check from time to time to verify all is well.
This link has info on the meters
http://www.eham.net/reviews/products/40?ehamsid=a9efc7e8e58a376ce24c0118effd
4579
The one I use is an MFJ-862 It has 2 needles for Forward and Reflected and
will read watts for both. This is a low price unit, definately not a high,
but had OK reviews. I have no idea if one can still buy it?
PaulW
Message 11
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Subject: | LED WigWag with B&C SSF-1 |
Bob, can I wire two LED landing and taxi lights per Page 3.0 (Ref DE 12/15/11)
but using a single switch (already installed and labeled in unflown RV-6) as shown
on Page 3.0 from 2003? Thank you
Message 12
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Subject: | Uneven dipole elements |
I'm wondering if it is now operating like a modified Windom antenna (not
straight at centre and different length elements). I also would like to
know if it is vertical or horizontal
Noel
-----Original Message-----
From: owner-aeroelectric-list-server@matronics.com
[mailto:owner-aeroelectric-list-server@matronics.com] On Behalf Of Robert L.
Nuckolls, III
Sent: March 30, 2012 12:16 AM
Subject: Re: AeroElectric-List: Uneven dipole elements
--> <nuckolls.bob@aeroelectric.com>
At 05:30 PM 3/29/2012, you wrote:
><dave.saylor.aircrafters@gmail.com>
>
>Bob,
>
>We managed to chop about 3 inches off the end of a dipole comm antenna.
>Would that have any appreciable effect on performance?
Sure, but if I were to give you a 'number' . . . it wouldn't
have much practical meaning. Is this an internal antenna?
Can't you splice it back on?
Bob . . .
Message 13
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Previous post should read: (Revision -D- 12/15/11)
Message 14
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Subject: | Uneven dipole elements |
At 06:46 PM 3/30/2012, you wrote:
>
>I'm wondering if it is now operating like a modified Windom antenna (not
>straight at centre and different length elements). I also would like to
>know if it is vertical or horizontal
This would be a vertically polarized antenna and
appears to be 1/2 wavelength. Is there enough
'bulk' at the coax end to house a small toroid
transformer?
There's another 1/2-wave kid on the block which
is actually a center-fed dipole with the feedline
running up the middle of the lower half of the
dipole. It's marketed as the Air Whip at
http://miracleantenna.com/shop-products/aviation/42
Emacs!
The black box houses the common-mode choke which
de-couples the feed line from the high-voltage
end of the dipole thusly.
http://tinyurl.com/78ph8nz
http://tinyurl.com/6ul4o6f
Waaayyy back when, there was a brief brush with
tiny toroids to match coax feedlines to center fed
dipoles the cores they used were very low
power handling . . . hence good for receive only.
The Antenna Dynamics product has the look and 'smell'
of a similar product. By the way, the reason it's
not 44" (half wave in free space) long is because
the lower 1/4 wave is in coax which is shortened
to about 14" by the coax velocity factor.
Miracle Antenna is a newer kid on the block
and gets very good reviews from their whole
customer base which includes amateur radio and
SWL applications.
Dave, is there any chance you can get the remnants
of the old antenna out? Putting one of these
in it's place would be a prudent move.
If that's not practical/possible, then splicing an
extension on the upper end to replace the cut off
length would be helpful . . . even if it lays off at
right angles to the antenna. This would serve as
an extension moving back toward 1/4 wave for the
upper element and/or 'capacity' hat to load the
shortened antenna thus making it look electrically
like a quarter wave.
Your antenna guy will know all about this and
will be able to help you with the patch.
Bob . . .
Message 15
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Subject: | Re: Uneven dipole elements |
We found a diagram of what we think the antenna looks like. I'll post of a
picture of it next week at the latest. It's a slanted-N shape similar to
an Archer.
Earlier I described equal-length parallel elements. Turns out they're
carbon reinforcements that aren't part of the antenna. I'll show them in
the picture when I post it.
I mistook them as part of the antenna because I was using a "wire sniffer"
to find the elements. I had the transmitter attached to the end we'd cut
off, and it was making the carbon strips, which aren't connected to the
antenna in any way I can see, display to the receiver wand as conductors.
Thanks to everyone for all the input. We'll get this figured out. I think
if I have to I can add a few perpendicular inches to the shortened end.
--Dave Saylor
On Fri, Mar 30, 2012 at 9:36 PM, Robert L. Nuckolls, III <
nuckolls.bob@aeroelectric.com> wrote:
> At 06:46 PM 3/30/2012, you wrote:
>
> noelloveys@yahoo.ca>
>
> I'm wondering if it is now operating like a modified Windom antenna (not
> straight at centre and different length elements). I also would like to
> know if it is vertical or horizontal
>
>
> This would be a vertically polarized antenna and
> appears to be 1/2 wavelength. Is there enough
> 'bulk' at the coax end to house a small toroid
> transformer?
>
> There's another 1/2-wave kid on the block which
> is actually a center-fed dipole with the feedline
> running up the middle of the lower half of the
> dipole. It's marketed as the Air Whip at
>
> http://miracleantenna.com/shop-products/aviation/42
>
> [image: Emacs!]
>
> The black box houses the common-mode choke which
> de-couples the feed line from the high-voltage
> end of the dipole thusly.
>
> http://tinyurl.com/78ph8nz
>
> http://tinyurl.com/6ul4o6f
>
> Waaayyy back when, there was a brief brush with
> tiny toroids to match coax feedlines to center fed
> dipoles the cores they used were very low
> power handling . . . hence good for receive only.
>
> The Antenna Dynamics product has the look and 'smell'
> of a similar product. By the way, the reason it's
> not 44" (half wave in free space) long is because
> the lower 1/4 wave is in coax which is shortened
> to about 14" by the coax velocity factor.
>
> Miracle Antenna is a newer kid on the block
> and gets very good reviews from their whole
> customer base which includes amateur radio and
> SWL applications.
>
> Dave, is there any chance you can get the remnants
> of the old antenna out? Putting one of these
> in it's place would be a prudent move.
>
> If that's not practical/possible, then splicing an
> extension on the upper end to replace the cut off
> length would be helpful . . . even if it lays off at
> right angles to the antenna. This would serve as
> an extension moving back toward 1/4 wave for the
> upper element and/or 'capacity' hat to load the
> shortened antenna thus making it look electrically
> like a quarter wave.
>
> Your antenna guy will know all about this and
> will be able to help you with the patch.
>
> **
>
> ** Bob . . .
>
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