Archive for October, 2007

J-Poles aren’t so simple afterall

I finally got my copper pipe J-Pole up on a modest mount and cabled into my ham shack. It works, but I stumbled into many interesting things that most folks seem to ignore. In addition to the many J-Pole tutorials on the Internet you should also consider:

Radio Mobile for RF Link Analysis

Here is a great tool for RF Analysis which:

  • Deals with diffraction effects,
  • Computes the Fresnel effects,
  • Handles elevation data from many different sources

RF Links have many issues that plaque all too many folks in charge of ensuring radios work as planned. A tool like this provides this kind of view…

radiomobile.png

With this tool you can understand why some RF links actually fade even when the two antennas are in complete view of each other. When the wavelengths get longer than light wild things happen. The program is free and, from what I can tell so far, works very well.

MFJ Antenna Analyzers

In the past few months I have been testing antennas and antenna ground systems for a series of articles on the main part of this web site…

http://www.cosjwt.com/

One piece of equipment which proved absolutely essential is the antenna analyzer from MFJ Enterprises. I have the older cousin of the MFJ-259B pictured here…

mfj-259b.jpg

Decoupling a J-Pole

When feeding a J-Pole is obviously makes sense to install a choke balun to ensure the outside of the coax shield does not conduct energy down the coax thus degrading the antenna pattern via additional radiator area. This article nicely discusses using beads to achieve the goal:

Connectors – N vs. PL259

Recently I specified some cables and connectors for an antenna system we are putting together at work. I stumbled across this…

http://www.eham.net/articles/5300

There are some good thoughts in there and, quite obviously, some belief systems in place.

For the average ham with max power on HF and something less on bands above 50MHz the following points worth consideration include:

Keep good track of your insurance claims…

Do you think your insurance company and the medical vendors will handle your paperwork for you flawlessly?

Will, actually, the do a pretty good job most of the time, but…

Sears rebate rejected

We purchased a nice new and very quiet dishwasher last month from the Warrenton, VA. It replaced the noisiest machine I have ever heard run without flying apart to pieces. It works great.

We were promised a rebate of some small amount as part of the deal. We sent it the paperwork and, of course, Sears rejected it.

The Football Coach’s Tape

For several years I have been filming my son’s football games. I always gave a copy to the coach for review. The tapes proved so useful I became a sort of official team videographer. During this time I have collected some tips that help me provide what the coach needs. In no particular order they are: