Map of QSO participants

I updated a pair of Google Earth map views to show the locations of participants in our morning round table QSOs on 75 m. These are extensions of the earlier maps I made a few years ago of participants in the Saturday Bell Ringers Net. Click on either graphic below for a full-size view. The place marker dot, not the call sign label, represents the location of each station.

The view above shows frequent and infrequent participants. Four range circles, centered on W4BXI, are labeled with each radius in miles.

This second view is zoomed in to better display the stations within 100 miles of W4BXI.

Baluns -- Under the Hood

Below are views of 3 baluns that I own, with their covers removed to see the internals. The first photo shows 2 LDG baluns that are rated for 200 W. The one on the left is a 1:1 current or choke-type balun. The one on the right is a 4:1 balun that appears to be a voltage-type balun.  For some in-depth discussion of balun types, see this article by W7EL.

LDG baluns

1:1 Current Balun

4:1 Voltage Balun

Above are schematics of the two LDG baluns, using graphics from the W7EL article.

The next 4 photos show the internals of a DX Engineering balun DXE-BAL050-H10-AT that is rated for 5 kW CW and 10 kW SSB.

-  John

Comparing 3 Feed Line Lengths

I added another 3 ft of 450-ohm ladder line to my antenna feed line, bringing the total length of ladder line to about 99 ft. Using data measured by my antenna analyzer, I compared the current data with what I collected with the previous lengths of 91 and 96 ft.  Below are graphs that compare the SWR and impedance (magnitude) for the 80 m and 40 m bands.

SWR 80 m

SWR 40 m

|Z| 80 m

|Z| 40 m

Click on any graph to view it full size. These graphs show the effects of lengthening the ladder line feed while keeping the antenna length constant at 102 ft end-to-end.

Bringing Gamma Back -- Alzheimer's Research

A December 2016 NPR Radiolab podcast reported on research using mice that discovered the beneficial effects of blue light flashing at the brain's gamma wave frequency, reversing Alzheimer's effects, at least temporarily. The audio program runs for almost 25 minutes and has a few promotional announcements (commercials).

Below the web page graphic are some recommended links for additional information.

This video link is a nice summary of the research with excellent computer animations.

YouTube provided this related link. It shows an 83-year old man who claims to have recovered from severe Alzheimer's symptoms with a certain daily medication combined with a few supplements and dietary elements associated with populations that do not develop Alzheimer's disease.

John

230 ft Multi-band Dipole

This posting provides a collection of antenna model graphs for a multi-band dipole with the following specs:

• 230 ft end-to-end horizontal
• 60 ft above ground
• 75 ft of 450-ohm balanced feeder

Model results are provided for the following bands: 160, 80, 60 and 40 m. For each band the graphs are:

• SWR at the transmitter end of the feed line
• Impedance data (R, X, |Z|, phase) at the transmitter end of the feed line
• Vertically polarized radiation pattern in the vertical plane
• Horizontally polarized radiation pattern in the horizontal plane

160 m SWR	160 m Z
160 m Vertical	160 m Horizontal
80 m SWR	80 m Z
80 m Vertical	80 m Horizontal
60 m SWR	60 m Z
60 m Vertical	60 m Horizontal
40 m SWR	40 m Z
40 m Vertical	40 m Horizontal