Baluns

Here are a few selected articles that were referenced during our recent on-air discussions of baluns, and voltage vs current baluns in particular:

Balanced - Unbalanced - Balanced, by VK5AJL
Lots of good definitions and illustrations.
See the comment posted below by N4NR. Other sources refute the author's contention that current baluns are only designed for 1:1 ratio.

Baluns: What They Do and How They Do It, by W7EL
An illustrated discussion by the author of EZNEC software.

Choosing the Correct Balun, by W8JI
An article that our group has consulted many times.

Broadband Baluns
Focus on air-core and ferrite-bead choke baluns.

Common Mode Chokes
A chart of impedance measurements

Special thanks to W4PRE who directed me to the Chattanooga Amateur Radio Club website that includes many good antenna-related topics on the Links page.

TPWINLOG Data Files

TPWINLOG 2015 creates the following data files to accomplish logging and scoring for the Telephone Pioneer QSO Party:

• BonusCall.txt
• Chapsworked.txt
• CWchapsworked.txt
• LogInFile.txt
• TPHistory.txt
• TPLogOut.txt
• tpqsolog.txt

If you need to edit any of these files independent of TPWINLOG, you must navigate to where they are stored on your system and use a plain text editor, such as Notepad, to make the edits. Be sure to make a backup copy of a file before editing.

The location of these files depends upon how you installed the program. Section 2.1 of the ReadMe file has the following information and suggestion:

THE INSTALL PROGRAM WILL INDICATE THAT IT IS GOING TO
WRITE THE FILES TO: C:\Program Files\TPQ
The install program will create the TPQ folder in the Program
Files folder. OR .. you can click the Change Directory command
button and install to some other folder. Those using Windows
Vista or Windows 7 may wish to change the path to C:\TPQ to
prevent file redirection. This makes finding program written (data)
files much easier.

CASE 1: If you follow this suggestion you will easily find all of the data files in C:\TPQ, as shown in the Windows Explorer screen shot below.

Click to enlarge.

CASE 2: If you allow the program to install to its default directory, the program and data files will reside in two separate directories. The program will be found in C:\Program Files (x86)\TPQ, along with initial copies of two data files that are write-protected, as shown below.

Click to enlarge.

To access the complete set of data files you must navigate to their directory by clicking the Compatibility files button as noted in red above. This will take you to the view that is shown below.

Click to enlarge.

The examples above are from my installations on Windows 7 PCs.

If you must know, the full path to this directory is:
C:\Users\John\AppData\Local\VirtualStore\Program Files (x86)\TPQ
and AppData is a hidden directory, but is easily reached using the Compatibility files button shown previously. Your username will be where "John" appears. You can edit and save the data files in this directory as discussed in the second paragraph above.

If you only need to add some new entries to TPHistory.txt, you can accomplish that from within TPWINLOG.  Enter the station's CallSign, Chapter and Name in the boxes near the bottom of the TPWINLOG window, then click HistoryFileAdd under the HistoryFile menu. Your new entry will be added to the end of the file.

Click to enlarge.

Send me an email or post a comment if you have any questions.

TPWINLOG 2015 -- History File

Based on some questions about how the history file is updated during contact entries in TPWINLOG, I performed some tests this morning.

When the program is installed, the original, default history file (from the downloaded zip file) TPHistory.txt is put into place. While the program is used, the first contact with new station that is not found in the original history file is added to the end of the history file.

We recommend that you practice using the program well in advance of the event, entering practice contacts. Before you start participating in the event you need to delete the log of practice contacts by choosing File, DeleteLog, as shown below.

My testing confirms that this delete function will clear out the following files:
   tpqsolog.txt
   Chapsworked.txt
   CWchapsworked.txt
It will not clear out the TPHistory.txt file. Subsequent use of the program will make use of any new station history data (not in the original history file) that was entered during your earlier use of the program. I tested this by entering a fictitious call sign that I knew was not in the original history file. 

Further testing reveals that changes (e.g. chapter #) made during subsequent contacts with any station will not be saved to the history file. However, TPWINLOG will (apparently) consult the tpqsolog.txt file first when subsequent contacts are made with the station whose details were changed on the previous contact entry. Naturally, those changes will be lost when the practice log file is deleted. Any station details that you wish to preserve need to be entered directly into the history file (using a plain text editor) so that they will be found when you start over with a blank log file. 

Also, if you do make changes to station data during the event, especially chapter changes, you will want to edit your final log file prior to printing results so that you don't end up with something like 2 chapter numbers recorded for the same call sign. 

Please send me email if anything above is not clear or if you have other questions.

Windows Computer Security -- Using a standard user account

By default Windows sets up the initial user account with full admin privileges. This makes it very easy for the user and for malware / spyware / adware publishers to install new programs on your computer. A study reported that of all the security patches issued by Microsoft in 2013, 92% of the vulnerability exploits would have been blocked by use a of standard user account.

Here is the process I have used successfully on 11 Windows 7 computers to convert an existing admin user account to a standard account:

Create a new admin account:

• Log in to your existing user account that has admin privileges
• Go to Control Panel, User Accounts
• Click Manage another account
• Click Create a new account
• Enter a name for the new account (e.g. Admin)
• Click the Administrator button
• Click Create Account
• Click on the new account icon
• Click Create a password
• Enter password (different from normal user password) in the two boxes
• Click the button Create password
• Return to desktop and log out of your normal user account

Downgrade normal user account to standard:

• Log in to your newly created admin account
• Go to Control Panel, User Accounts
• Click Manage another account
• Click on the normal user icon
• Click Change the account type
• Click Standard user
• Click the button Change Account type
• Return to desktop and log out of your admin account

Log in to your normal account and resume use

If you attempt to install a new program or an upgrade (other than Microsoft updates), you will be prompted to enter the password for an admin account. Pay close attention! If this appears for a program you don't recognize or did not choose to install, it may be malware attempting to install.

On rare occasions (in my experience) a program may need to be installed or updated when logged into an admin account. In most, but not all cases, you may be able to simply right-click on the program file and select "Run as administrator". 

Updates 3/27/15: 

• One example of a program that must be run from a logged-in admin account is Evernote. When I am using the program from my standard account and it announces an update available, it tells me to ask my administrator to install the update. It does not make the update available to install by my standard account.
• Many programs allow me to install updates by simply entering my admin password when the UAC pop-up box appears. In some cases the update downloads go to my admin user's download folder rather than to my standard user download folder.

I believe that the same or very similar steps would apply to Windows 8 computers.


Also see these three rules for online security published by Brian Krebs. 

3 Antennas Compared

Recently we discussed the comparative performance of 3 wire antennas, sized for 80 m, on 3.5 MHz and above. I used antenna modeling to compare the following antennas, all at 40 ft above rocky ground:

• W8JI 110 ft dipole
• Horizontal Loop of 287 ft
• 133 ft Off-Center Fed Dipole

I found that the shapes of the radiation patterns vary, but the peak total gain figures are similar among the 3 for the two frequencies I used: 3.5 and 7.2 MHz. Here is a summary of results:

	Maximum Total Gain (dB)
	@ 3.5 MHz	@7.2 MHz
110 ft dipole	5.53	6.59
Horizontal Loop of 287 ft	6.39	5.83
133 ft OCF Dipole	5.74	6.42

Radiation patterns for the 2 frequencies are shown in this PDF file. If you zoom in enough you can read the data on each graph.  Patterns for additional frequencies are easily generated.

I used a similar side-by-side presentation in this 2010 posting when comparing two antennas sized for 160 m (110 ft or 130 ft wire to each side of the feed point).

WA5MLF

Feedline Loss & Other Characteristics

Here are some online resources you can use to calculate the loss and other characteristics for specified feedline types or geometries:

• Cable Loss  (coaxial & ladder line)
• Coaxial Cable Calculator
• Coaxial Cable Power Ratings
• Coaxial Cable Equations
• Coax Cable Impedance Calculator

 If you want to find this and other posts in the future, be sure to use the blog's search feature. Look for this search box at the top left corner of the blog page

and enter your search term there.

In response, one or multiple blog postings will be presented if your search term matches one of the labels attached to a posting. This posting has the following labels attached: antenna, feedline, SWR.

End Fed Zep Antenna by N4NR

After some recent morning QSOs on 3740 kHz, there was email discussion about the antenna used by N4NR from his campground location in coastal Georgia. Several of our morning regulars were impressed by the 10 W SSB signal from Dennis. The antenna is an End Fed Zep. (This is a correction to my earlier posting.)

Based on an email response from Dennis, I put together a model of his campground antenna. For my initial analysis I did not include his RV, but a later analysis could add a metallic screen near the vertical portion of the antenna to approximate its effects. I expect that this would show up mainly on the higher bands where the radiation angles are lower.

Below is a series of screen captures from the 4nec2 antenna modeling software to illustrate the theoretical behavior of the antenna. Click on any graphic for a larger view.

First is a view of the antenna structure. 17 ft of 450-ohm ladder line starts at the rig (tuner), goes about 2 ft horizontally, then 15 ft up a fiberglass pole. A single wire, connected to one side of the ladder line, continues up to 22 ft, then continues on an upward angle to a height of about 50 ft for a total length of 84 ft. The other side of the ladder line constitutes the counterpoise. The graphic is to scale, so the two conductors of the ladder line are hard to distinguish. On this version I also used the program's feature to depict the magnitudes of current in the structure, represented by the short green lines. 
The ground parameters are for "marshy, forested flat ground", and the wires are all 12-gauge copper.

Antenna Structure

Next is a series of 12 screen shots showing radiation patterns for four selected frequencies.  I included patterns for total gain, vertically polarized and horizontally polarized. All patterns are oriented in the same direction as the structure graphic above (x-axis and horizontal wires going to the right). The total and vertical patterns are from a low angle facing the antenna broadside, and the horizontal patterns are from directly above the antenna. Click on the slide show below for a better view of the individual slides.



Below you can view impedance plots for two frequency ranges: 3 to 14 MHz and 3 to 29 MHz. Click on any image for a larger view.

Impedance Parameters, 3-14 MHz

Impedance Parameters, 3-29 MHz

Happy New Year!
John WA5MLF