Today's Message Index:
----------------------
1. 05:43 AM - Re: VHF antenna mounting (rd2@evenlink.com)
2. 09:35 AM - Re: VHF antenna mounting (Robert L. Nuckolls, III)
3. 09:37 AM - Re: VHF antenna mounting (FLYaDIVE@aol.com)
4. 10:02 AM - Antennas general (Hinde, Frank George (Corvallis))
5. 11:20 AM - Re: Antennas general (Ralph E. Capen)
6. 11:59 AM - Re: Antennas general (Hinde, Frank George (Corvallis))
7. 01:10 PM - Re: Antennas general (Brian Lloyd)
8. 03:26 PM - Re: Antennas general (Ralph E. Capen)
9. 05:04 PM - Re: Antennas general (europa flugzeug fabrik)
Message 1
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| Subject: | VHF antenna mounting |
_____________________Original message __________________________
(received from Robert L. Nuckolls, III; Date: 10:36 PM
7/25/2006 -0500)
________________________________________________________________
----other inserts snipped-----
I published a mate-up sketch to the website a few months ago:
http://www.aeroelectric.com/Pictures/Antenna/Antenna_Installation.gif
The emphasis for "grounding" the base of the antenna to structure
needs to concentrate on the areas around fasteners where mate-up
pressures assure the "gas tight" condition. Removal of paint or
material surface protection any place else is a waste of time and
only exposes those surfaces to the ravages of atmosphere. All the
magic happens right around the screws and no place else.
Bob . . .
----------------------------
Bob,
Speaking of the magic (grounding the base) - looking at the
Antenna_Installation.gif ,
I have seen toothed lock washers used between the doubler plate and skin.
This was on a Cessna. The doubler plate was not riveted to the skin (it
came with with the antenna replacement kit). The lock washer assured better
el contact (grounding). They used externally toothed lock washers, as per
attached. Maybe a better idea would be to use the external-internal toothed
type washers (also attached). Opinions?
Rumen
Message 2
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| Subject: | VHF antenna mounting |
--> AeroElectric-List message posted by: "Robert L. Nuckolls, III" <nuckollsr@cox.net>
At 08:18 AM 7/26/2006 -0400, you wrote:
>_____________________Original message __________________________
> (received from Robert L. Nuckolls, III; Date: 10:36 PM
>7/25/2006 -0500)
>________________________________________________________________
>
>----other inserts snipped-----
>
> I published a mate-up sketch to the website a few months ago:
>
>http://www.aeroelectric.com/Pictures/Antenna/Antenna_Installation.gif
>
> The emphasis for "grounding" the base of the antenna to structure
> needs to concentrate on the areas around fasteners where mate-up
> pressures assure the "gas tight" condition. Removal of paint or
> material surface protection any place else is a waste of time and
> only exposes those surfaces to the ravages of atmosphere. All the
> magic happens right around the screws and no place else.
>
> Bob . . .
>
>----------------------------
>
>Bob,
>Speaking of the magic (grounding the base) - looking at the
>Antenna_Installation.gif ,
>I have seen toothed lock washers used between the doubler plate and skin.
>This was on a Cessna. The doubler plate was not riveted to the skin (it
>came with with the antenna replacement kit). The lock washer assured better
>el contact (grounding). They used externally toothed lock washers, as per
>attached. Maybe a better idea would be to use the external-internal toothed
>type washers (also attached). Opinions?
We're really slice'n and dice'n mouse hairs here. Obviously
the goal is to get a low ohms connection between the antenna
base and the skin that is as good 10 years from now as it is
the day we bolt it on. This comes down to a few simple-ideas:
(1) pressure high enough to bring two clean surfaces into intimate
gas tight contact with each other and (2) exclusion of environmental
effects that include (a) contaminants and (b) loosening that work
against condition (1).
Some designers embrace the idea that the toothed lockwashers
provide a multitude of very high pressure points . . . even to
the point of upsetting metal at the points of contact to achieve
(1). My concerns are that a toothed washer is a spacer between
the two surfaces that may contribute to initial joint quality (1)
but leaves the gap "open" for ingress of (a).
In all of our bonding specs at RAC, the use of lockwashers is
never suggested. Self locking all metal nuts are the preferred
anti-loosening technology. In the sketch I published, 99% of the
magic needs to happen in the area just around the screw hole and
between skin and antenna base. All other "prepared" areas add
only marginally to the quality of the joint.
Obviously, the "99% conductivity area" is of very small gap and
the only thing one might add is sealant or anti-moisture guckum (Like
silocone grease) to fill the tiny void around the periphery
of the 99% area to prevent entry of oxidizing agents. Beyond
that, maintainance of pressure over time is enhanced by use
of largest practical hardware torqued to upper limits and
secured with some form of locking technology . . . all metal
locknuts being the technology of choice.
When we were selling contactors with treaded studs for fat wires,
the split-ring, steel washers supplied were discarded and replaced with
internal tooth, phosphor bronze lockwashers. The supplied steel
nuts were replaced with brass. Again, the lion's share of conductive
magic happens were the terminal comes down against the bottom nut.
The lockwasher and nut on top contributes to conductivity but
only a tiny fraction of the total.
Bob. . .
Message 3
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| Subject: | Re: VHF antenna mounting |
--> AeroElectric-List message posted by: FLYaDIVE@aol.com
In a message dated 7/26/06 8:48:44 AM Eastern Daylight Time, rd2@evenlink.com
writes:
> I have seen toothed lock washers used between the doubler plate and skin.
> This was on a Cessna. The doubler plate was not riveted to the skin (it
> came with with the antenna replacement kit). The lock washer assured better
> el contact (grounding). They used externally toothed lock washers, as per
> attached. Maybe a better idea would be to use the external-internal toothed
> type washers (also attached). Opinions?
>
> Rumen
====================
Rumen:
By putting washers between the skin and the doubler you do not create a
doubler, the would-be doubler now becomes a spring and you also create individual
stress points at each screw. Their may also be some crazy RF issues; better to
do it like the book/manufactur says.
The idea of improving the ground contact is good but that can be done with a
clean surface, snug screw holes and star washers under the nuts.
The type of star washer you suggest is perfectly acceptable. Just not
between the skin and doubler.
Barry
"Chop'd Liver"
"Show them the first time, correct them the second time, kick them the third
time."
Yamashiada
Message 4
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| Subject: | Antennas general |
--> AeroElectric-List message posted by: "Hinde, Frank George (Corvallis)" <frank.hinde@hp.com>
On my Vans kit they provided a wingtip NAV antenna which is just a
strip of copper foil. Do not suggest how one is supposed to ground it to
the airframe.
I assume one has to ground the coax braid to the wing somehow??
Also I intend to run my marker beacon antenna (40" lentgh of stripped
coax) in the bottom of my cowl. Assuming this will work do I need to
bond that coax to the firewall or similar?
Thanks
Frank
Rv 7a...Finishing..No really I am finishing..:)
Message 5
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| Subject: | Re: Antennas general |
--> AeroElectric-List message posted by: "Ralph E. Capen" <recapen@earthlink.net>
Frank,
For the wingtip NAV, IIRC the coax shield is to be grounded with the shield approx
where it ends and the foil begins.
For my marker beacon, I am using bulkhead fittings to penetrate the firewall so
I am considering mine grounded to the SSFirewall.
I'm gonna use the 40" stripped coax on the bottom of my cowl too - along with another
stripped length (gotta figure out the math) for my AM/FM/MP3 player.
When you're really finished and flying - come visit N06 Laurel, DE....
Ralph
-----Original Message-----
>From: "Hinde, Frank George (Corvallis)" <frank.hinde@hp.com>
>Sent: Jul 26, 2006 12:58 PM
>To: aeroelectric-list@matronics.com
>Subject: AeroElectric-List: Antennas general
>
>--> AeroElectric-List message posted by: "Hinde, Frank George (Corvallis)" <frank.hinde@hp.com>
>
> On my Vans kit they provided a wingtip NAV antenna which is just a
>strip of copper foil. Do not suggest how one is supposed to ground it to
>the airframe.
>
>I assume one has to ground the coax braid to the wing somehow??
>
>Also I intend to run my marker beacon antenna (40" lentgh of stripped
>coax) in the bottom of my cowl. Assuming this will work do I need to
>bond that coax to the firewall or similar?
>
>Thanks
>
>Frank
>
>Rv 7a...Finishing..No really I am finishing..:)
>
>
>
>
>
>
>
Message 6
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| Subject: | Antennas general |
--> AeroElectric-List message posted by: "Hinde, Frank George (Corvallis)" <frank.hinde@hp.com>
Now there is an idea...I just passed my RG56 thru a grommet in the
firewall but a bulkhead fitting would take care of the grounding...I
have not fire sealed it yet so I might do the same thing...assuming
Radio Shack sells the fittings of course.
Thanks Ralph
Frank
-----Original Message-----
[mailto:owner-aeroelectric-list-server@matronics.com] On Behalf Of Ralph
E. Capen
Sent: Wednesday, July 26, 2006 11:16 AM
--> AeroElectric-List message posted by: "Ralph E. Capen"
--> <recapen@earthlink.net>
Frank,
For the wingtip NAV, IIRC the coax shield is to be grounded with the
shield approx where it ends and the foil begins.
For my marker beacon, I am using bulkhead fittings to penetrate the
firewall so I am considering mine grounded to the SSFirewall.
I'm gonna use the 40" stripped coax on the bottom of my cowl too - along
with another stripped length (gotta figure out the math) for my
AM/FM/MP3 player.
When you're really finished and flying - come visit N06 Laurel, DE....
Ralph
-----Original Message-----
>From: "Hinde, Frank George (Corvallis)" <frank.hinde@hp.com>
>Sent: Jul 26, 2006 12:58 PM
>To: aeroelectric-list@matronics.com
>Subject: AeroElectric-List: Antennas general
>
>--> AeroElectric-List message posted by: "Hinde, Frank George
>--> (Corvallis)" <frank.hinde@hp.com>
>
> On my Vans kit they provided a wingtip NAV antenna which is just a
>strip of copper foil. Do not suggest how one is supposed to ground it
>to the airframe.
>
>I assume one has to ground the coax braid to the wing somehow??
>
>Also I intend to run my marker beacon antenna (40" lentgh of stripped
>coax) in the bottom of my cowl. Assuming this will work do I need to
>bond that coax to the firewall or similar?
>
>Thanks
>
>Frank
>
>Rv 7a...Finishing..No really I am finishing..:)
>
>
>
>
>
>
>
Message 7
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| Subject: | Re: Antennas general |
--> AeroElectric-List message posted by: Brian Lloyd <brian-yak@lloyd.com>
On Jul 26, 2006, at 12:58 PM, Hinde, Frank George (Corvallis) wrote:
> --> AeroElectric-List message posted by: "Hinde, Frank George
> (Corvallis)" <frank.hinde@hp.com>
>
> On my Vans kit they provided a wingtip NAV antenna which is just a
> strip of copper foil. Do not suggest how one is supposed to ground
> it to
> the airframe.
>
> I assume one has to ground the coax braid to the wing somehow??
>
> Also I intend to run my marker beacon antenna (40" lentgh of stripped
> coax) in the bottom of my cowl. Assuming this will work do I need to
> bond that coax to the firewall or similar?
Not really. A 50W transmitter shooting its signal at you using a
directional antenna when you are less than 2000' away does not
require much from the receiver and its antenna. The signal level is
so high that making a perfect antenna is not necessary.
Brian Lloyd 361 Catterline Way
brian-yak AT lloyd DOT com Folsom, CA 95630
+1.916.367.2131 (voice) +1.270.912.0788 (fax)
I fly because it releases my mind from the tyranny of petty things . . .
Antoine de Saint-Exupry
Message 8
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| Subject: | Antennas general |
--> AeroElectric-List message posted by: "Ralph E. Capen" <recapen@earthlink.net>
They might - but digi-key does for sure.......
-----Original Message-----
>From: "Hinde, Frank George (Corvallis)" <frank.hinde@hp.com>
>Sent: Jul 26, 2006 2:55 PM
>To: aeroelectric-list@matronics.com
>Subject: RE: AeroElectric-List: Antennas general
>
>--> AeroElectric-List message posted by: "Hinde, Frank George (Corvallis)" <frank.hinde@hp.com>
>
>Now there is an idea...I just passed my RG56 thru a grommet in the
>firewall but a bulkhead fitting would take care of the grounding...I
>have not fire sealed it yet so I might do the same thing...assuming
>Radio Shack sells the fittings of course.
>
>Thanks Ralph
>
>Frank
>
>-----Original Message-----
>[mailto:owner-aeroelectric-list-server@matronics.com] On Behalf Of Ralph
>E. Capen
>Sent: Wednesday, July 26, 2006 11:16 AM
>
>--> AeroElectric-List message posted by: "Ralph E. Capen"
>--> <recapen@earthlink.net>
>
>Frank,
>
>For the wingtip NAV, IIRC the coax shield is to be grounded with the
>shield approx where it ends and the foil begins.
>
>For my marker beacon, I am using bulkhead fittings to penetrate the
>firewall so I am considering mine grounded to the SSFirewall.
>
>I'm gonna use the 40" stripped coax on the bottom of my cowl too - along
>with another stripped length (gotta figure out the math) for my
>AM/FM/MP3 player.
>
>When you're really finished and flying - come visit N06 Laurel, DE....
>
>Ralph
>
>-----Original Message-----
>>From: "Hinde, Frank George (Corvallis)" <frank.hinde@hp.com>
>>Sent: Jul 26, 2006 12:58 PM
>>To: aeroelectric-list@matronics.com
>>Subject: AeroElectric-List: Antennas general
>>
>>--> AeroElectric-List message posted by: "Hinde, Frank George
>>--> (Corvallis)" <frank.hinde@hp.com>
>>
>> On my Vans kit they provided a wingtip NAV antenna which is just a
>>strip of copper foil. Do not suggest how one is supposed to ground it
>>to the airframe.
>>
>>I assume one has to ground the coax braid to the wing somehow??
>>
>>Also I intend to run my marker beacon antenna (40" lentgh of stripped
>>coax) in the bottom of my cowl. Assuming this will work do I need to
>>bond that coax to the firewall or similar?
>>
>>Thanks
>>
>>Frank
>>
>>Rv 7a...Finishing..No really I am finishing..:)
>>
>>
>>
>>
>>
>>
>>
>>
>>
>>
>>
>>
>>
>
>
>
>
>
>
>
>
>
>
>
>
Message 9
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| Subject: | Re: Antennas general |
--> AeroElectric-List message posted by: "europa flugzeug fabrik" <n3eu@comcast.net>
brian wrote:
> A 50W transmitter shooting its signal at you using a directional antenna when
you are less than 2000' away does not require much from the receiver and its
antenna.
I believe theyre as little as 2.5W, though as highly directional, the moral equivalent
of higher power relative to like a COM. Perhaps you are referring to
that.
Also, the sensitivity of the receiver isnt good, maybe 200 times less sensitive
than a COM. So, the antenna has to be reasonably good. I wonder if we could
use wire or copper tape to fake an equivalent of a sled antenna. One end to
shield, center wire about 10 down or wherever, but we need a ramp tester to tune
it. Or rig it up in the car, and find a marker shed we can drive up close
to. A coax monopole w/o ground plane as proposed will probably be OK.
Fred F.
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