RADIOACTIVITIES Newsletter of the Argonne Amateur Radio Club
Volume XLVI, Number 2	February, 2005

Directions to room E1100: Park in the 401 lot and walk up the stairs of the main entrance, the auditorium building will be on your right (it looks like a big ice cream cone). Enter the 401 main entrance (with the revolving door) and proceed slightly to your right about 40 feet to a hallway behind the APS auditorium. E1100 will be right around the corner on your right. You can page Chuck Doose at 4-1037 from any lab phone if you need assistance. You can buy your lunch at the cafeteria and get it to go, or there is a “401 Grill” on the first floor of the APS below the Gallery area. Here’s a link to the menu: www.aps.anl.gov/travel/menu/agh_grill_menu.htm.

If you want to attend and do not have an Argonne badge, contact Chuck Doose 630-252-6037 doose@aps.anl.gov who will arrange for a gate pass.

If you haven’t paid for 2005, you will have an X in the lower right corner of your mailing label & an application form is attached. If I don’t receive your application form by Feb 25, this will be your last newsletter. The March newsletter will contain a rerun of the access codes for the repeater and membership lists. The membership lists will consist of three lists: 1) full list sorted by last name, 2) e-mail list sorted by call suffix, and 3) full list sorted by call suffix with addresses and phone numbers.

10		N9QGU		Bob		Willowbrook, IL
10		K9GF		George		Berwyn, IL
20		WD9GTI		Richard		Crest Hill, IL
25		K9AGY		Charles		Chicago Ridge, IL
26		W9MVP		John		Park Ridge, IL
27		KA9CRU		Henry		Joliet, IL
28		W9NIX		Don		Woodridge, IL

If I have an e-mail address for you in the database & you leave that field blank on the application form, I will delete your e-mail address from my database (I have deleted 2 or 3 already.). If you want an e-mail address in the data base so it is included on the membership list, but cannot receive the e-mail newsletter, let me know; I’m working on that now. That is one of the bugs that I have to work out. You can e-mail me with your wishes. If you do not get an e-mail copy of this newsletter, either I don’t have your e-mail address, or I don’t have it correct, or you have requested not to receive the e-mail copy. If you want the e-mail copy & didn’t receive it, send me an e-mail with your e-mail address & tell me what you want.

The coaxial dipole has been used to broaden the frequency over simple wire dipole, and as a coaxial resonator/matcher also as part of a radiator becoming an aerial. See 1995 ARRL handbook Pg.20.14, an article by AI1H in Apr 89 QST, this is a simple resonant feed line dipole, and on page 20.17 of the same book we find another one by W2OZH appeared in Aug 91 QST. However this aerial must be as high and in the clear as possible.

All coax has a certain capacity per foot and impedance ranging from 20.6 to 30.8 picofarads and impedance from 50 to 75 ohms, and coax cable is like a little capacitor every foot of the length in use. Thumbing through my log book, I found AF9J 80 meter dipole he used back in the 1980’s he said it was quiet low noise and used a Heathkit big linear the warrior. The heart of the antenna is RG8U and number 12 copper wire sections. How to make one is not hard to make but explain.

Cut 2 lengths of coax 32 feet long then cut number 12 copper wire (2 needed) 29 feet 6 inches. Take one 32-foot coax section; at one end solder the shield to the center conductor and one wire section. Due the same to the other wire and coax length. The feed line coax RG8U and solder feed line coax center conductor to one coax center conductor then solder the feed line shield to the other leg coax shield. And then the remaining shield solder to the remaining center conductor. All coax open ends use bathtub caulk and be generous. After setting a few days go and check it. Exposed places should be caulked again with more caulking compound sealing from bad weather. Hoist the antenna up at the center, forming a vee apex angle greater than 90 degrees.

I found that this all started on FM a coaxial 3 section with whip on top as a last section. Always use solid dielectric coax for these antennas for best effects and efficiency. It was in the 1940’s I include a drawing of it for 2 meters.

A coaxial antenna used by WA6IFO from an article Sep 80 Ham Radio Horizons for 80 through 10 meters. He used a coaxial cable reversed in phase from the transmission line and ends with a 50-ohm dummy load 100-watt resistance. WA6IFO used a Drake DL300 dummy load. Seal coax line ends with weather proofing bathtub caulk. The aerial uses 3 sections A, L, & B. Section A any length shield is grounded at the feed point of A use ground stakes only place there is a ground on the whole antenna. Next end of coax A attaches soldered to section L 40 feet or more A center conductor to L shield and A shield to L center conductor then L attaches to B section a random length. L shield to B center conductor and L shield attaches to B center conductor the other end of B goes to 50-ohm 100V var resistance. WA9IFO reports good SWR 1.25 to one on any band and length L should be as long as possible. It isn’t a hot antenna, but puts out workable signals on all bands.

WA9IFO devised another coax antenna but for 40 meters it uses link coupling between antenna and transceiver. He loads a 47-foot length of coax using the shield as the radiator. The center conductor is not connected at the end of the coax at the other end is a RF ammeter grounded.

The working end of the coax shield has a 13-turn 1-1/2 diameter coil at 8 turns per inch. The xmtr link coil 4 turns wound on to the 13 turns and the 13 turns tie to one end of 150pf variable capacitor grounded the 4 turn link is grounded. Tune up maximum RF current flowing through RF ammeter by tuning the capacitor.

Early coax design each section of line serves both as a radiator and coupler to the adjacent section terminated by a quarter wave whip overall height nearly 8 feet.