SWR: Does it matter?

SWR and baluns were discussed during several of our recent morning QSOs. We combined personal experiences and many on-line references in order to better appreciate the topic.

• Understanding SWR by Example by K5DVW is a must-read article. (You can skip the Smith Chart section.) The article illustrates how transmission line loss can easily be a greater issue than SWR when trying to transfer maximum power to the antenna. 
• VSWR Myths includes a similar set of examples and goes on to discuss various common myths. 
• The Easy Way is a wordy article that also makes the case for non-resonant antennas and tuners to operate across multiple HF bands. Four topics covered in separate sections of the article are: Antennas of non-resonant length, Line attenuation,the Transmatch, and the Balun.

A few online calculators enable you to estimate the losses due to SWR:

• SWR Loss Calculator
• Types of Coax Cable and Line Loss
• Misunderstanding VSWR misleads - This article discusses some pitfalls of such calculators and provides a link to a more sophisticated calculator. Look for TWLLC on that page.

Many articles explore the use of baluns in all sorts of HF antennas:

• Choosing the Correct Balun by W8JI provides guidelines for several antenna types. An area of particular interest in our group discussions is the multi-band  dipole with balanced feeder. A table in this article includes recommended element and feed line dimensions. I found a second version of this article that has a copy of Table 1 with data for both 300-ohm and 450-ohm feeders.W8JI has lots of other content on his web site.
• Baluns in Antenna Systems by VK1OD analyzes several balun usage scenarios and compares their modeled behaviors, with conclusions for each. Other references are provided. The author's home page has links to lots of content.
• Baluns: What They Do and How They Do It by W7EL gives a detailed explanation, with sketches, of what issues a balun is intended to solve. The article includes the results of field experiments to support conclusions about balun use, but also with further questions. W7EL is the author of EZNEC software.

Finally, from G4NVH comes HF Balanced Transmitting Systems, a 75-page compilation of materials from various sources. See the table of contents and pick your favorite topics!


John

Visit to KB4LWT

Here are photos from Gary N4OLN's visit to Larry KB4LWT. The outdoor photos show some views of Larry's loop antenna.

Hunter Bandit Linear Refurb by N4MYT

Click here for a report from N4MYT about the power supply refurbishment of his Hunter Bandit linear amp.

Here are photos from W4BBW taken at this summer's reenactment festivities at Ider, AL.

 

Contest Resources from W4EA

During recent morning discussions of ham radio contests, Dan W4EA, an enthusiastic contest operator,  shared some resources for our consideration. His emails provided web links to various contest calendars, operating tips, and logging software (i.e. N1MM). I've added these links as two new groups in our Bell Ringers Links page. You'll see them in the third row of the matrix there.

Thanks, Dan!

Six Meter Beacon at NØSAP

 
Here is the announcement from NØSAP about his new beacon:

As of Saturday, November 5th, 2011 I have a new Six Meter Beacon on the air.  The frequency is 50.063.5 running 8 watts to a J-Pole with a Alinco DX-70.  I think this is the only six meter beacon in the State of Missouri.  Any reports will be appreciated.  "SAP"  NØSAP

 There is a posting on QRZ.com with many comments. 

 

Pioneers award to TPARCA in 1995

Here is a bit of TPARCA history from 1995.

KE4ID's article in October CQ magazine

Jack's article about restoration of a National NC-81X has been published in the October 2011 issue of CQ Magazine. Congratulations, Jack!

Huntsville Hamfest 2011

Here are two photos from our traditional gathering at noon on Saturday at the Huntsville Hamfest. Thanks to N4OLN for the photos! Click on the photos for an expanded view. A captioned copy of the first photo is posted at the group photos page.

 

VoIP Phone Patch

Below is a drawing of the VoIP phone patch configuration that I have been using for a few months. Click on the image for a full-sized view.

I'm using the phone patch audio input & output jacks of the transceiver. Modern transceivers should work in a similar manner with their line audio input & output jacks. A RIGblaster Pro forms the interface between transceiver and the PC sound card. Many other forms of audio interface can serve the same function.

The vintage SoundBlaster sound card has 4 audio jacks: line in, line out, speakers, and microphone. The line in and line out jacks connect to their corresponding jacks on the RIGblaster. My headset microphone connects to the microphone jack. I've been using the convenient headphone jack on the RIGblaster with my headset earphone(s), but I need to try the sound card speaker jack to see if its performance is any different. This setup provides ample audio levels, except for the audio from the distant phone to my earphones.

The Windows-based audio mixer associated with the sound card provides the ability to combine and adjust the level of my voice along with the distant phone voice when transmitting. I'm able to hear the distant caller's voice and my own (i.e. sidetone), but I'd like to be able to reduce the latter a bit. I can mute my own voice with a mouse click in the Windows audio mixer.

In the receive direction, I can supply as much audio as needed for the distant phone party, using the transceiver's audio gain. This tends to provide more audio than needed for my local earphone(s).

For the VoIP connection to the distant phone, which is connected to the public switched telephone network (PSTN), I've been using the Google Call Phone feature in Gmail. It is free again this year, and does not max-out the 600 MHz CPU in my ham shack PC. A PC with adequate CPU power can use Skype for the same function, but calls to PSTN phones require a paid Skype subscription. Group voice chat / calls are apparently not supported on the Google platform at this time. Skype has good capabilities for conferencing multiple participants on PC-based Skype clients or on PSTN phones.

Doublet antenna for 7-30 MHz

Yesterday our discussion on 3740 kHz included the characteristics of a wire doublet antenna for 7 thru 30 MHz, based on recommendations (see page 8) from W8JI. Below are links to screen shots from NEC-based analysis of the antenna, for two lengths: 55 ft and 66 ft. Analysis used 3/8 wavelength of 300 ohm feeder, to conform to the article's recommendation to use odd multiples of 1/8 wavelength for the feeder.

55 ft antenna, with radiation patterns in horizontal plane and a plot of impedance for the 7 ham bands. The data points in the latter are the frequencies where computations were done. For the impedance plot, connecting lines drawn thru the intervening non-ham frequencies should be ignored.

W8JI 55 ft doublet

Click on individual thumbnails when the album opens, or select the slideshow mode.

66 ft antenna, with same plots and same feeder & height above ground.

W8JI 66 ft doublet

Radiation patterns for vertical plane are not included here, but are readily available.

John

W4S Special Event Station

Here is some pictures from the special event station W4S April 9th and 10th from Pigeon Forge, Tennessee.

The four people in the above photo from left to right are

Paul WA0BAG, Sap N0SAP, Steve WA9JNM and Smitty KB4BW.

Above is a picture of Jim KC4RD operating the Ten-Tec Eagle.

73's Steve  WA9JNM

Video by WA9JNM

Thanks, Steve!

Pigeon Forge and TenTec factory

Here are some pixs from Pigeon Forge and TenTec factory with their new
radio.  KB4BW & KC4RD were with me.

Bruce
K4CMC

Titanic Special Event - April 9 & 10

Remember the Titanic April 9th and 10th in Pigeon Forge, TN.  

Hope to see you there.  N0SAP "SAP"

---

This Special Event is to honor the two brave radio operators Jack Phillips and Harold Bride for the 99th Anniversary of the Titanic tragic sinking. The WØS at the World's Largest Titanic Museum in Branson, MO. and the W4S World's Second Largest Museum in Pigeon Forge, TN. will be held as an open event for all hams and non-hams to operate. The "W" and "S" is for White Star the shipping company of the Titanic. Ten-Tec will display the new "Eagle" Transceiver for all to use in the Pigeon Forge, TN. location. We will be operating around the clock from both locations. Come experience being chased by stations from around the world at this International Famous Special Event Station.

Operating frequencies will be as follows for SSB and CW.
14.260 ssb +/- 3KC
7.260 ssb # +/- 3KC
3.860 #ssb #+/- 3kc

CW will be running split
14.060 CW UP 2kc
7.060 CW UP 2kc
3.560 CW UP 2kc

For more information and future updates the websites are:
www.w4sspecialevent2011.bravehost.com
www.wzeros.com

Antenna party at Zamora

Here is a set of photos from the antenna party organized by KE4ID at the Zamora Temple site used during Field Day in recent years. The objective was to compare the performance of several antennas in advance of Field Day. Click on the slide show thumbnail if you wish to view individual photos in the web album.

BirmingHAMfest Group Photo

A photo of our group's gathering at the 2011 BirmingHAMfest joins the many that appear on the Group Photos page linked to our home page.

When you arrive at that page you'll also see reference to W4AXO's presentation. A link to his new logging program is included there and also on the Telephone Pioneer QSO Party page that is linked to our home page.

Java update breaks chat room copy/paste

UPDATE: See comments at bottom of this posting for a solution that works for all versions of Java.

Regular users of the Bell Ringers chat room know that it requires Java to be loaded by the web browser so the addonChat applet can run. Recently I accepted the latest update -- Java 6 Update 24. I considered this worthwhile since the update patched multiple vulnerabilities.

On the next morning I noticed that I could not paste a web link or any other text into my outgoing chat message bar. If you never have the urge to paste a URL or other text into your message bar, you can ignore the rest of this post.

Pasting URLs, etc. has become a popular way of sharing diverse discussion topics and sources of additional information during our morning QSOs. I soon suspected the Java update as a trigger for the trouble. Through the addonChat support page I submitted the issue and got a speedy response. I assume that the paying business customers of addonChat brought up the issue right away. Here is an excerpt from their reply:

We've just recently been made aware of apparent bugs in the latest build of Java 1.6. This security release appears to have unintentionally disabled both copy and paste using CTRL/CMD commands as well as hot-linking to remote images using the IMG tag.

We're currently awaiting further information from Oracle regarding this and hope their next build resolves these issues.

In the meantime, we recommend uninstalling Java from your system and downgrading to Java 1.6.0_23 (Java 1.6 build 23). You may download a copy from http://www.oldapps.com/java.php

Below you will find the steps to uninstall Java update 24 and reinstall Java update 23. Java defaults to notify (or update) you automatically, so you will want to disable this action until we determine that a subsequent Java update resolves this issue.

For Windows XP:

• First, use Control Panel, Add or Remove Programs and remove Java 6 Update 24
• Go to: http://www.oldapps.com/java.php and download Java 6 Update 23
• Install Java 6 Update 23
  
• Disable updates:
• Go to Control Panel, open Java Control Panel
• On the Update tab, Un-check the Check for Updates box
• On the Warning page that pops up, choose never

For Windows 7:

• First, use Control Panel, Programs and Features and remove Java 6 Update 24
• Go to: http://www.oldapps.com/java.php and download Java 6 Update 23
• Install Java 6 Update 23 (I chose the x64 version for my Win 7 laptop)
  
• Disable updates:
• Go to Control Panel, open Java Control Panel
• On Advanced tab, expand JRE Auto-Download
• Check Never Auto-Download
• Click OK

If, during the Java update 23 installation you get an offer to add the Yahoo! toolbar, I suggest that you decline it (un-check box), unless you really want it. 

That should cover it. When I get word of Java 6 Update 25, I'll test it for chat copy & paste and advise.

(This blog entry updated 4/6/11)

75 m Voice & Video Party

This morning we had quite a crowd on 3740 LSB and occasional CW. We also tried out Carl's expanded Adobe Acrobat.com account with ConnectNow web conferencing.

Carl shared his desktop, showing TRX-Manager software, with a multitude of our participant log-ins and web cams. Below is one of the screen shots I captured during the peak of activity. Click on the thumbnail below for a full size image.

Recently we've used the desktop sharing feature to share live demonstrations of SDR software (by KE4ID) and antenna modeling software (by WA5MLF). Carl has used the desktop sharing on numerous occasions to demonstrate TRX-Manager, Ham Radio Deluxe, and Master Commander software for local and remote control of ham radio systems.

ConnectNow is a powerful and fun tool for sharing knowledge among members of the group.

Antenna radiation patterns - 220 ft dipole

Here are some radiation patterns for this antenna for 160 thru 10 m bands, using 40 ft height above rocky ground. No feedline was used for this analysis; the source was located at the mid-point of the antenna.

Each slide identifies the frequency and orientation (vertical plane or horizontal plane). The maximum gain (red line) and -3 dB gain points (green lines) are marked. A short horizontal red line near the center of most plots represents the antenna structure, oriented broadside to the viewer. For 40 - 10 m, 3D color plots are also included. A white line in those plots represents the antenna structure. x, y and z axes (barely showing) are in green.

Click on the image below to access the slide set where you can play a slide show or view individual slides.

Dipole, 220 ft, 160 - 10 m