---------------------------------------------------------- AeroElectric-List Digest Archive --- Total Messages Posted Sat 12/08/18: 6 ---------------------------------------------------------- Today's Message Index: ---------------------- 1. 09:47 AM - Bob Archer comm antenna dimensions ? (GTH) 2. 10:47 AM - Re: Bob Archer comm antenna dimensions ? (Charlie England) 3. 11:38 AM - Re: Bob Archer comm antenna dimensions ? (GTH) 4. 01:16 PM - Re: Bob Archer comm antenna dimensions ? (Charlie England) 5. 08:48 PM - Re: Bob Archer comm antenna dimensions ? (The Kuffels) 6. 09:27 PM - Re: Bob Archer comm antenna dimensions ? (The Kuffels) ________________________________ Message 1 _____________________________________ Time: 09:47:52 AM PST US From: GTH Subject: AeroElectric-List: Bob Archer comm antenna dimensions ? Hi all, Some 15 years ago we ordered a Bob Archer comm antenna for installation in our wingtip, and have been very satisfied with it. Here is a sketch of our 15 year old antenna : A buddy of mine launches into another project and just received a new Archer antenna to install in his tail fin, but the dimensions and shape seem different, and the rivets prevent the upper segment from being swept up to fit into the tail. Although the antenna is labelled "Comm", we are finally not sure the model is a VHF one. Does any of you gentlemen have any information as to the shape and dimensions of the present time Archer comm antennas - or VOR antennas - so we could clarify the matter ? Thanks in advance, -- Best regards, Gilles http://contrails.free.fr http://lapierre.skunkworks.free.fr ________________________________ Message 2 _____________________________________ Time: 10:47:57 AM PST US Subject: Re: AeroElectric-List: Bob Archer comm antenna dimensions ? From: Charlie England On 12/8/2018 11:46 AM, GTH wrote: > > Hi all, > > Some 15 years ago we ordered a Bob Archer comm antenna for > installation in our wingtip, and have been very satisfied with it. > > Here is a sketch of our 15 year old antenna : > > > A buddy of mine launches into another project and just received a new > Archer antenna to install in his tail fin, but the dimensions and > shape seem different, and the rivets prevent the upper segment from > being swept up to fit into the tail. > > Although the antenna is labelled "Comm", we are finally not sure the > model is a VHF one. > > Does any of you gentlemen have any information as to the shape and > dimensions of the present time Archer comm antennas - or VOR antennas > - so we could clarify the matter ? > > > Thanks in advance, > > > -- > Best regards, > Gilles > http://contrails.free.fr > http://lapierre.skunkworks.free.fr Pretty sure that if you could see side by side images of all the Sportcraft antennas, you'd see significant differences among the various antennas. IIRC, there are different models for RV-4-8, the -9, & -10 wing tips. The vertical fin would be yet another design. The VOR antennas would be yet another set. Did he make sure that the model he bought is recommended for his a/c, and for the location where he intends to mount it? Charlie --- This email has been checked for viruses by Avast antivirus software. https://www.avast.com/antivirus ________________________________ Message 3 _____________________________________ Time: 11:38:22 AM PST US Subject: Re: AeroElectric-List: Bob Archer comm antenna dimensions ? From: GTH /Le 08/12/2018 19:49, Charlie England a crit: / > /Pretty sure that if you could see side by side images of all the > Sportcraft antennas, you'd see significant differences among the > various antennas. IIRC, there are different models for RV-4-8, the > -9, & -10 wing tips. The vertical fin would be yet another design. The > VOR antennas would be yet another set. > / / > Did he make sure that the model he bought is recommended for his a/c, > and for the location where he intends to mount it? > / Hi Charlie, Thank you for responding. His project is a composite homebuilt that certainly no one knows outside our country. The antenna is to be located in the glass fiber fin, but as it is a small airplane, there no room for a 1/2 wave antenna. Provided the model is a correct comm antenna the actual question is, can we pivot the radiating element so as to match the fin, like in red in the following diagram Of course this would involve removing some rivets, but from an electrical point of view, would such a "sweep" be acceptable ? Thank you, -- Best regards, Gilles http://contrails.free.fr http://lapierre.skunkworks.free.fr ________________________________ Message 4 _____________________________________ Time: 01:16:06 PM PST US From: Charlie England Subject: Re: AeroElectric-List: Bob Archer comm antenna dimensions ? On Sat, Dec 8, 2018 at 1:42 PM GTH wrote: > > *Le 08/12/2018 =C3- 19:49, Charlie England a =C3=A9crit : * > > > *Pretty sure that if you could see side by side images of all the > Sportcraft antennas, you'd see significant differences among the various > antennas. IIRC, there are different models for RV-4-8, the -9, & -10 win g > tips. The vertical fin would be yet another design. The VOR antennas woul d > be yet another set. * > > * Did he make sure that the model he bought is recommended for his a/c, > and for the location where he intends to mount it? * > > > Hi Charlie, > > Thank you for responding. > His project is a composite homebuilt that certainly no one knows outside > our country. > The antenna is to be located in the glass fiber fin, but as it is a small > airplane, there no room for > a 1/2 wave antenna. > Provided the model is a correct comm antenna the actual question is, can > we pivot the radiating element so as to match the fin, like in red in the > following diagram > > > Of course this would involve removing some rivets, but from an electrical > point of view, would such a "sweep" be acceptable ? > > Thank you, > > -- > Best regards, > Gilles > http://contrails.free.fr > http://lapierre.skunkworks.free.fr > I'm no antenna expert, but I'd bet that a base loaded whip (like a 'rubber ducky' off a handheld) would work about as well as radically altering the tuning of the Archer antenna. Or maybe not. :-) Virus-free. www.avast.com <#DAB4FAD8-2DD7-40BB-A1B8-4E2AA1F9FDF2> ________________________________ Message 5 _____________________________________ Time: 08:48:58 PM PST US From: "The Kuffels" Subject: Re: AeroElectric-List: Bob Archer comm antenna dimensions ? Gilles, I used to be an antenna expert. The Archer antenna should work better with the radiating element unbent. I n fact, it would work best with the radiating element at 90 degrees to the base. But you might have a bigger issue. This antenna requires a mass of metal, like a wing, electrically connected along the base to serve as a gro und plane. Does the aircraft have a metal fuselage or stabilizer. Another issue is the rudder tube, if metal. If the distance from the front of the rudder to the antenna radiator is too short, say around a foot or t wo, you will have a null in your reception toward the rear. The problem is even worse if the rudder is also metal. A possible solution might be a bent 1/2 wave dipole. The 1/4 wave part fed by the coax center wire would fit up the fin from the base, essentially th e same as the radiating element on the Archer. The other half of the dipol e would be attached forward to the underside of the fuselage top. The shie ld of the coax would be attached to this other half. Sort of an L in profi le from the right side with the coax cable attached at the bend. I would u se copper sheet 1/2 - 3/4 inch wide for the elements. If this simple antenna is not possible for some reason then more complex ar rangements start appearing such as dual end coil loaded dipoles. This coul d be made to fit in the fin but then you are getting into the area of much tinkering and antenna analyzers, etc. Tom Kuffel --- This email has been checked for viruses by Avast antivirus software. https://www.avast.com/antivirus ________________________________ Message 6 _____________________________________ Time: 09:27:10 PM PST US From: "The Kuffels" Subject: Re: AeroElectric-List: Bob Archer comm antenna dimensions ? Gilles, What model Archer antenna does your friend have. Archer offers a compresse d dipole (looks like a weird "3") model SA006 which is 26.5" tall by 12" wi de. At some $190 it is a bit pricey but should fit if your unbent wing tip mode l would have. Tom --- This email has been checked for viruses by Avast antivirus software. https://www.avast.com/antivirus ------------------------------------------------------------------------------------- Other Matronics Email List Services ------------------------------------------------------------------------------------- Post A New Message aeroelectric-list@matronics.com UN/SUBSCRIBE http://www.matronics.com/subscription List FAQ http://www.matronics.com/FAQ/AeroElectric-List.htm Web Forum Interface To Lists http://forums.matronics.com Matronics List Wiki http://wiki.matronics.com Full Archive Search Engine http://www.matronics.com/search 7-Day List Browse http://www.matronics.com/browse/aeroelectric-list Browse Digests http://www.matronics.com/digest/aeroelectric-list Browse Other Lists http://www.matronics.com/browse Live Online Chat! http://www.matronics.com/chat Archive Downloading http://www.matronics.com/archives Photo Share http://www.matronics.com/photoshare Other Email Lists http://www.matronics.com/emaillists Contributions http://www.matronics.com/contribution ------------------------------------------------------------------------------------- These Email List Services are sponsored solely by Matronics and through the generous Contributions of its members.