---------------------------------------------------------- AeroElectric-List Digest Archive --- Total Messages Posted Wed 07/26/06: 9 ---------------------------------------------------------- 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 _____________________________________ Time: 05:43:45 AM PST US From: rd2@evenlink.com Subject: RE: AeroElectric-List: 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 _____________________________________ Time: 09:35:56 AM PST US From: "Robert L. Nuckolls, III" Subject: RE: AeroElectric-List: VHF antenna mounting --> AeroElectric-List message posted by: "Robert L. Nuckolls, III" 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 _____________________________________ Time: 09:37:13 AM PST US From: FLYaDIVE@aol.com Subject: Re: AeroElectric-List: 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 _____________________________________ Time: 10:02:42 AM PST US From: "Hinde, Frank George (Corvallis)" Subject: AeroElectric-List: Antennas general --> AeroElectric-List message posted by: "Hinde, Frank George (Corvallis)" 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 _____________________________________ Time: 11:20:08 AM PST US From: "Ralph E. Capen" Subject: Re: AeroElectric-List: Antennas general --> AeroElectric-List message posted by: "Ralph E. Capen" 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)" >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)" > > 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 _____________________________________ Time: 11:59:11 AM PST US From: "Hinde, Frank George (Corvallis)" Subject: RE: AeroElectric-List: Antennas general --> AeroElectric-List message posted by: "Hinde, Frank George (Corvallis)" 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" --> 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)" >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)" > > 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 _____________________________________ Time: 01:10:17 PM PST US From: Brian Lloyd Subject: Re: AeroElectric-List: Antennas general --> AeroElectric-List message posted by: Brian Lloyd On Jul 26, 2006, at 12:58 PM, Hinde, Frank George (Corvallis) wrote: > --> AeroElectric-List message posted by: "Hinde, Frank George > (Corvallis)" > > 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 _____________________________________ Time: 03:26:08 PM PST US From: "Ralph E. Capen" Subject: RE: AeroElectric-List: Antennas general --> AeroElectric-List message posted by: "Ralph E. Capen" They might - but digi-key does for sure....... -----Original Message----- >From: "Hinde, Frank George (Corvallis)" >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)" > >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" >--> > >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)" >>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)" >> >> 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 _____________________________________ Time: 05:04:04 PM PST US From: "europa flugzeug fabrik" Subject: AeroElectric-List: Re: Antennas general --> AeroElectric-List message posted by: "europa flugzeug fabrik" 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. Read this topic online here: http://forums.matronics.com/viewtopic.php?p=50033#50033