FoxDelta Analyzer at Tuner Input

Here is an example of what the FoxDelta Antenna Analyzer sees when connected to the input of my LDG AT-100Proll. The graph has plots for three frequencies at which the tuner was tuned:

• 3740 kHz  - Blue curve
• 7191 kHz  - Red curve
• 14200 kHz - Green curve

Click on the image above for a magnified view. 
All plots were done with my 80 m horizontal loop antenna connected to the output of the tuner. For each frequency I performed the following steps:

• Tuned the tuner for minimum SWR with the transceiver as a source at the selected frequency
• Connected the analyzer in place of the transceiver
• Ran a scan from the analyzer software

Using the analyzer mode that enables 3 separate scans to be displayed on a single graph, I saved the composite graph and added frequency labels next to the color legend at the bottom of the graph.

You can see that a good dip in SWR is obtained for first two frequencies. At 14200 kHz, however, the short (84-ft) feed line length did not allow the lowest SWR to be obtained within the 20 m band.

TPWINLOG -- Editing log file

During a morning HF roundtable QSO we discussed the ability to edit a log file created by TPWINLOG. Section 7 of the program's ReadMe file discuss the format of the log file.

A user may want to edit the log file in scenarios such as:

• Error (e.g. name or call sign) discovered just after a contact is logged
• Duplicate contact logged intentionally with DUPE tag for later correction
• Error in band or mode recognized and noted for correction while not operating the event

UPDATE 23 Oct 2020: In the most recent versions of the program the log file is named tpqsolog.txt. The instructions below are otherwise still valid.

After exiting the TPWINLOG program, during a break in operating or after the event concludes, you may use a plain text editor program (e.g. Notepad) to edit your log file QSOLOG5.TPQ. It would be prudent to first make a backup copy of the file. When editing the file, it is best to avoid changing the lengths of certain data elements: chapter, band, mode, date, time. The call sign, name, and comment fields will be of variable length.  After editing QSOLOG5.TPQ, when you run TPWINLOG the contact log display and scoring will be updated to reflect the edits. Now you can run the Print feature to generate the output log report on paper or in a file for emailing.

Below is a series of screen shots showing a log of 5 practice log entries and an edit applied to one contact. (Click on any image to expand the view.) The first shows a 5th contact was identified by the program as a duplicate, but was accepted by the operator as a DUPE entry and is not counted in the tally of 4 contacts.

The next screen shows the QSOLOG5.TPQ file opened in a plain text editor. In this example, the operator forgot to change the band to 80 m, but logged the contact as a dupe for later edit. He could have changed the band before Inserting (logging) the contact.

The next screen highlights the changes in the band and the comment field (removing the DUPE tag).

Finally, when the TPWINLOG program is re-started, the log screen reflects the revised tally of 5 contacts.

As noted previously, it's a good idea to practice using the program to log practice contacts and to print the log results. Just be sure to delete the practice contact log before CQ TP starts. See section 4.1 of the program's ReadMe file.

TPWINLOG Installation

The TPWINLOG program available at this web page was developed by W4AXO to enable logging and CW send functions for the annual Telephone Pioneer QSO Party. This posting supplements the installation instructions provided in the Readme file for the TPWINLOG program. Below is a series of screen shots collected during installation and initial setup of the program.

Installation begins with extraction of the setup files from TPQD.zip, as shown here. Run setup.exe to begin the process. (Click on any image for an enlarged view.)

Here is the initial setup screen. Click OK when ready.

Click on the button shown in this screen shot to continue. You have the option of changing the installation directory before proceeding, as noted in section 2.1 of the Readme file. Some pop-up messages may appear as described in section 2.2.

This screen confirms the successful installation.

For convenience, create a desktop shortcut to the program file TPWINLOG V1b.exe as discussed in section 2.4.

Here is a magnified view of the resulting shortcut icon on the desktop.

Here is the welcome screen that appears when the program starts.

This window tells you that the next step is to input your user information for the program to use.

Here is the form that you fill in once to record your information as discussed in section 3.1. You can replace or edit this information if changes are needed afterward.

Each time you start the program you will have the option to open the Com Port for CW sending. A simple interface for this feature is described in section 10 of the Readme file.





Be sure to study the program usage details in sections 4 through 10 of the ReadMe file.
You should practice using the program before the event, but be sure to delete your file of practice contacts before you start logging for the event. See section 4.1 of the ReadMe file.

Huntsville Hamfest 2014

Here is the group photo from the Huntsville Hamfest. (Click on the photo for a larger view.) Many more photos can be seen at this site. I'll also add the group photo to the Bell Ringers web site.

Loop SWR by FoxDelta Antenna Analyzer

W4UOA gave me the opportunity to assemble and evaluate / use his FoxDelta Antenna Analyzer kit FD-AAZ-0912. The assembly was easy, given that 3 surface-mount devices were pre-soldered to the main board or a daughter board. The initial power-up was successful and the device appeared to be mostly ready to go. The Windows software advised that the device firmware needed to be updated to be compatible with the current v 5.03 software. This was easily accomplished using the published instructions and the firmware updater program. A quick calibration with open circuit and short circuit conditions on the BNC antenna port made the device fully ready. The necessary instructions and programs are available at this web page.

I used various features of the analyzer to profile the SWR of my 80 m horizontal loop antenna. The analyzer settings default to measuring 600 points across the designated frequency range, whose default is 1 to 35 MHz. The 47-page user guide covers all the features, but it is very easy to use. There are convenient buttons to quickly select a single band for analysis. A scan of 600 points takes 25 seconds on my ham shack PC. The number of points to scan can be specified in the software. I found that 200 points still gave satisfactory displays, especially for a smaller frequency range. A table of the scan data is also available with the click of a button. Both the graphic display and the table can be exported easily. When the graphic is displayed following a scan, the mouse pointer can be moved anywhere on the graph to display numeric values of SWR and frequency.

Below is a scan of my 80 m loop with a 4:1 balun connected to the 450-ohm feeder. (Click on the image to enlarge.) The gray vertical bands mark the amateur radio band frequencies. The SWR curve has nice dips in or near the 80, 40, 20, 15, and 10 m bands, but not at 60 m. The SWR scale is on the right side, return loss on left side, and the frequency scan is from 3 to 30 MHz, with 600 points of data. A deep dip in SWR occurs near 10.6 MHz, and this is consistent with SWR data calculated from antenna modeling software.

On the 60 m band I've found it necessary to use a 1:1 balun to bring the SWR within range for my automatic antenna tuner, I made a scan using the 1:1 balun. The result is displayed below. Although the SWR is manageable on 60 m, other bands are compromised.

A similar result is obtained with a different 1:1 (choke) balun as shown below.

Returning to the 4:1 balun, I tested the effect of shortening the feed line by 9 ft.  The plot is shown below, and has the same scales as the previous plots. It is easy to see that the shorter feed results in the SWR dips moving higher in frequency. A closer examination of the table data would reveal whether the shift causes significant SWR increase within most of each affected band. The SWR at 60 m is not improved.

Since the FoxDelta analyzer is so convenient to use, I may make additional scans with even shorter feed line lengths before I settle on a final configuration.  It appears that the 1/2 wavelength feed at the lowest band is probably optimal.

Feeding a Multi-band Dipole Antenna

During recent on the air discussions we revisited the design options for a multi-band dipole antenna with balanced feeder. Design guidelines for a slightly-shortened dipole antenna are published in the document Choosing the Correct Balun by W8JI. The recommended lengths of balanced feedline are based on odd multiples of 1/8 wavelength on the lowest frequency of operation. This is covered on pages 7 & 8 of W8JI's document.

Some of our group wondered if the same feedline recommendations would apply to a standard half-wave dipole as they do to the slightly-shortened dipole. To explore this topic I used the 4nec2 antenna modeling software to analyze a half-wave dipole of total length 134 ft (12 ga copper) at 30 ft above rocky ground. This length is close to resonance at 3.5 MHz. The shortened dipole in the article, to cover 80 m and above, has length 110 ft.

I collected data for the feed point impedance at one frequency on each of six bands. I also expanded the model to use a 450-ohm feedline of length 30.48 ft (close to the 1/8 wave length of 30.9) and collected the impedance data at the end of the feedline for the same 6 frequencies. The results are shown in the graph and table below.

The graph clearly shows the wide variation of impedance (orange bars) at the feedpoint, while the impedance at the xmt end of the feedline (blue bars) shows that the impedance variation is considerably narrowed. This supports the comments on page 7 of the W8JI document.  At 7 MHz the dipole becomes a full wavelength, with very high impedance, but the feedline -- 1/8 wavelength at 3.5 MHz -- becomes 1/4 wavelength at 7 MHz, thus transforming to a much lower impedance.

The table below gives the data used in the graph. I did not include the resistance and reactance data, but they are readily available.

f (MHz)	Z (xmt)	Z (fp)
3.5	338	56
5.3	539	1156
7	105	5970
14	839	2433
21	453	1637
28	225	1180

This analysis covers only the 1/8-wavelength feeder case, but any other lengths (e.g 3/8, 5/8) can be analyzed easily.

John

VoIP Patch: Links

As background, here are some links (in reverse date order) to blog postings about the topic. Several of us morning regulars, especially W4BXI and W4UOA, have put together and tested various configurations over the past five years. The configurations have been successful for the great majority of the time, but testing has revealed some configurations that work better than others or are easier to operate than others.

There are many variations of PC hardware and different ways to use the available VoIP services. 

http://thebellringers.blogspot.com/2014/02/voip-patch-discussion.html

http://www.w4uoa.com/2013/03/dual-skype-one-computer-skype-patch.html

http://www.w4uoa.com/2013/01/w4bxi-napkin-patch_25.html

http://wa5mlf.blogspot.com/2012/03/sound-card-controls-for-voip-patching.html

http://wa5mlf.blogspot.com/2012/03/voip-patch-update.html

http://thebellringers.blogspot.com/2011/07/voip-phone-patch.html

http://thebellringers.blogspot.com/2009/09/latest-w4bxi-system-audio-drawing.html

http://thebellringers.blogspot.com/2009/08/voip-hf-radio-bridge-in-qst.html

http://thebellringers.blogspot.com/2009/04/w4bxi-system-audio.html

http://www.w4uoa.com/2008/08/voip-hf-bridge.html