---------------------------------------------------------- AeroElectric-List Digest Archive --- Total Messages Posted Fri 05/21/10: 6 ---------------------------------------------------------- Today's Message Index: ---------------------- 1. 04:45 AM - Re: Terminating Coax Cable to VOR Antenna (Robert L. Nuckolls, III) 2. 04:56 AM - Re: Terminating Coax Cable to VOR Antenna (George, Neal E Capt USAF ACC 505 TRS/DOJ) 3. 05:43 AM - Re: Terminating Coax Cable to VOR Antenna (Eric M. Jones) 4. 05:49 AM - Re: Terminating Coax Cable to VOR Antenna (Mike Welch) 5. 06:08 AM - Re: Terminating Coax Cable to VOR Antenna (Robert L. Nuckolls, III) 6. 06:19 AM - Re: Re: Terminating Coax Cable to VOR Antenna (Robert L. Nuckolls, III) ________________________________ Message 1 _____________________________________ Time: 04:45:20 AM PST US From: "Robert L. Nuckolls, III" Subject: Re: AeroElectric-List: Terminating Coax Cable to VOR Antenna At 09:36 PM 5/20/2010, you wrote: I have a RAMI AV-12 VOR antenna that has the two machine screws/studs for electrical connection to the coax cable -- it doesn't take a BNC twist-on connector. I believe the coax that I have is a double shielded type but it isn't RG400 -- it has a bright yellow outer jacket. How did you acquire the ooax? Did it come with the antenna as a kit? How do I terminate this coax cable to this antenna? Do I just crimp PIDG terminals (or solder suitable lugs?) to the braided shield and to the center conductor? Yes, make the lengths of these leads as short as practical. I'd also use some heat-shrinked tubing. Is anything more than this required? Nope. Bob . . . ________________________________ Message 2 _____________________________________ Time: 04:56:16 AM PST US Subject: RE: AeroElectric-List: Terminating Coax Cable to VOR Antenna From: "George, Neal E Capt USAF ACC 505 TRS/DOJ" Bob - Connectors appropriate to the antenna's lugs, either crimped or soldered will do just fine. Keep the length of exposed center conductor to a minimum. Support the cable with a clamp very near the end of the jacket, fastened to the airframe to provide strain relief and vibration protection. Neal ==================== How do I terminate this coax cable to this antenna? Do I just crimp PIDG terminals (or solder suitable lugs?) to the braided shield and to the center conductor? I'd also use some heat-shrinked tubing. Is anything more than this required? Best regards, Bob Falstad GlaStar N248BF 310 Hours in two years ________________________________ Message 3 _____________________________________ Time: 05:43:25 AM PST US Subject: AeroElectric-List: Re: Terminating Coax Cable to VOR Antenna From: "Eric M. Jones" For frequencies near or above 1 MHz, coaxial cables are best terminated with a connection method that is easy to make or buy that avoids the unnecessary losses in pigtailing the shield. Yes, you can "get away with" pigtails, but Google "Kimmel Gerke pigtails" and learn how to do this important task.... And see my "Dabbling with Electricity...It's Child's Play" attached for more explanation. (I have also attached for your pleasure the Popular Mechanics 1943 Army Test.) -------- Eric M. Jones www.PerihelionDesign.com 113 Brentwood Drive Southbridge, MA 01550 (508) 764-2072 emjones@charter.net Read this topic online here: http://forums.matronics.com/viewtopic.php?p=298415#298415 Attachments: http://forums.matronics.com//files/army_test_173.pdf http://forums.matronics.com//files/dabbling_with_electricity_994.pdf ________________________________ Message 4 _____________________________________ Time: 05:49:14 AM PST US From: Mike Welch Subject: RE: AeroElectric-List: Terminating Coax Cable to VOR Antenna > How did you acquire the coax? Did it come with the > antenna as a kit? > Bob . . . Bob=2C Yes=2C it does. One of the two experimental planes I'm building is a Gl aStar. When ordering some of their options=2C I got the dipole com radio a ntenna kit. Evidently=2C whoever they have build their antennas likes to u se this triax cable. I got the com antenna fastened to the inside of the vertical stabilizer =2C and glued the two halves of the plane together. I forgot to look at ho w they handle the antenna end of the cable=2C that's why I asked previously about the balun information. In the present topic=2C do I understand correctly that you combine the in ner and outer shields together on the solder lug=2C at the antenna end? Mike Welch _________________________________________________________________ The New Busy is not the too busy. Combine all your e-mail accounts with Hot mail. http://www.windowslive.com/campaign/thenewbusy?tile=multiaccount&ocid=P ID28326::T:WLMTAGL:ON:WL:en-US:WM_HMP:042010_4 ________________________________ Message 5 _____________________________________ Time: 06:08:18 AM PST US From: "Robert L. Nuckolls, III" Subject: RE: AeroElectric-List: Terminating Coax Cable to VOR Antenna At 07:46 AM 5/21/2010, you wrote: > How did you acquire the coax? Did it come with the > antenna as a kit? > Bob . . . Bob, Yes, it does. One of the two experimental planes I'm building is a GlaStar. When ordering some of their options, I got the dipole com radio antenna kit. Evidently, whoever they have build their antennas likes to use this triax cable. Just making sure it wasn't some form of ohterwise un-identified cable . . . I got the com antenna fastened to the inside of the vertical stabilizer, and glued the two halves of the plane together. I forgot to look at how they handle the antenna end of the cable, that's why I asked previously about the balun information. Adding the balun is a technically satisfying thing to do for this style antenna but will offer no observable improvement in your VOR system performance. In the present topic, do I under stand correctly that you combine the inner and outer shields together on the solder lug, at the antenna end? Yes, you can do that. But if you do the elegant breakout of the center conductor through the shields like . . . http://aeroelectric.com/articles/shldwire/shldwire.html . . . you'll find that the bulk of strand for two sets of shields demand a rather hunky PIDG terminal. This is an exceedingly non-critical application that doesn't really benefit from double-shielding. At the antenna end, you can simply cut away all of the outer shield at the outer jacket and terminate only the inner shield as suggested above. Bob . . . ________________________________ Message 6 _____________________________________ Time: 06:19:54 AM PST US From: "Robert L. Nuckolls, III" Subject: Re: AeroElectric-List: Re: Terminating Coax Cable to VOR Antenna At 07:41 AM 5/21/2010, you wrote: > >For frequencies near or above 1 MHz, coaxial cables are best >terminated with a connection method that is easy to make or buy that >avoids the unnecessary losses in pigtailing the shield. > >Yes, you can "get away with" pigtails, but Google "Kimmel Gerke >pigtails" and learn how to do this important task.... In this case, we're making a transition between a coaxial feed line and pieces of metal intended to be exceedingly NON-coaxial, I.e. elements of an antenna. Pig-tails on the end of the coax simply become part of the total length of each antenna element. The existence or non-existence of a constant impedance connector at the end of the coax is not a factor for over-all performance. The technically elegant design will shorten the elements by the same dimension added by the pigtails. This adjustment for length will produce a more satisfying SWR plot over the range of interest . . . but it's not going to make an observable difference in system performance. In this instance, doing the PIDG-on-pig-tails termination provides a more robust, lower parts- count transition between the feed line and the antenna elements without degrading performance. If one opted for a pristine connector, then a mating connector needs to be part of the antenna assembly. The same pig-tails from the mating connector to each antenna element will exist and have the same influence on the antenna's resonant frequency. Parts count and numbers of connections go up. The K&G admonitions for preserving feed-line integrity are quite accurate but not applicable in this instance. Bob . . . ------------------------------------------------------------------------------------- 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.