W4AXL Tour

Thanks to W4BXI for the great pictures!

Dayton Hamvention 2010 “Amateur of the Year"

Congratulations to Jim Stafford, W4QO, BellSouth retiree (1993) and Bell Ringer # 164, public service advocate and well-known QRP enthusiast, who has been named Dayton Hamvention 2010 Amateur of the Year.

Thanks to Phil, KB4XX, for notifying us of Jim's award.

N0SAP Mobile

Here are a few photos sent by N0SAP, showing his mobile CW setup. Sap did not explain if he has a hands-free adapter for the CW rig! Hi.
Reply from Sap: 'I am working on the hands-free adapter next using mind control.  "SAP"  N0SAP'

Bell Ringers & TPARCA at BirmingHAMfest 2010

Here are a few photos from the BirmingHAMfest. I'll post a copy of the group photo with names and callsigns in the group photos section of the Bell Ringers web site. Many other photos are available on the MCARS web site at this link.


Attendees at our Saturday forum included: David KC4SBP, George KW7GAM, Carl W4UOA, Bob WA4PWA, Pat W4QAT, Ed W4DGH, Fletch W4BBW, John W4BXI, Hank K4HM, Selene KG4RMT, Ron N4DLE, Dennis N4NR, Hjordis KI4TVB, Ben W4CT, Bill KB4PYR, Phil KB4XX, Myra K3PGH, John WA5MLF.

Bob WA4PWA told us about a fascinating new device that interfaces his cell phone with his hearing aids. It is the iCom communications interface from Phonak.

David KC4SBP was looking for folks who worked for Southern Bell at the Hurt Building. I suggested that he should also explore the MaBellHams group on Yahoo.

Dennis N4NR gave us a brief history of the WireNet, a bulletin board predecessor to TPARCA.org. The active community from all continents of the world enjoyed sharing information and programs on WireNet, which also provided Internet email before the RBOCs started their ISP units. We are indebted to Dennis and Jerry Pruett (SK) for establishing the foundation of today's TPARCA.org.

130' vs 110' for Multiband Doublet Antenna

See this document for a first pass analysis of the antenna choices that W4BXI is considering.

W1TP Telegraph & Scientific Instrument Museums

Friday's snow in Birmingham was not sufficient to keep folks away from an excellent presentation by Bell Ringer #263 about the history and technology of the German Enigma cipher machine. A reference in Keith's presentation contains a video that reenacts the use of the machine during WWII. 

A visit to the W1TP home page reveals a treasure trove of information and photos of interest to collectors and historians. The focus is on telegraph equipment and scientific instruments and the Enigma. One of his web pages contains some nice photos from the 2009 Dayton Hamfest.

Enjoy!

75 m Loop Antenna at W4UOA

Corrected version -- original had results for double the intended loop length.
Here is some analysis of a loop antenna proposed by W4UOA. The following slide show presents impedance vs frequency for several bands. Resistance and reactance are plotted in the upper half of each slide, and impedance magnitude and phase are in the lower half. Click on any slide to view it in the source album. Additional magnification is available using the magnifier icon in the Picasa album view.



The radiation patterns below show the typical progression in frequency, with more lobes and lower angle of radiation as frequency increases. There is a large amplitude difference between the peaks and nulls in the patterns at higher frequencies.



The antenna elements and support wires are the silver lines. The feedline is blue. The color-coded radiation pattern was left at original scale to show its relationship to the antenna structure. The program allows zooming the pattern much larger, such that the antenna structure is engulfed. Viewing at any azimuth and elevation angle, in increments of 5º, is available. Standard 2-D plots are also available.

The predicted performance of this antenna seems consistent with other published analyses of loop antennas, and does not appear to be adversely affected by un-grounded metallic support wires.