Friday, December 19, 2008

HF Noise - Plasma TVs

This morning's discussion of digital flat screen TVs included a mention of plasma TVs as a source of RF noise that can affect HF radio. An article with comments from 2002 describes this issue. Thanks to KB4XX for this link.

The ARRL hosts an RF noise page that includes audio recordings of various identified noise sources, along with waveform views. There is not one currently labeled as a plasma TV, but there are some entries for TV sets as noise sources.

If you or your neighbors buy plasma TVs and you notice an increased noise level across the HF bands, you may want to see if the noise correlates to operation of the plasma TV. Good luck!

Thursday, December 18, 2008

Russian Woodpecker

Old timers on the HF bands will remember the Russian woodpecker. Go here for a web article with great photos of the antenna array. Thanks to Joe KA4ZCO for the link.

Monday, December 8, 2008

Understanding Antennas

Smitty KB4BW suggested the web page Understanding Antennas for the Non-Technical Ham. It provides access to a PDF copy of a 74-page book by Jim Abercrombie, N4JA.

Friday, November 14, 2008

Global Tuners

GlobalTuners is a web site that provides free access to radio receivers around the world. After creating a free account with log-in, you can access a receiver and listen to a frequency of your choice. Since the receivers are being shared by others, you must follow the web site's protocol of requesting permission to change a frequency, if others are listening to the current frequency. A chat window is provided to facilitate communication among concurrent listeners.

Thanks to W4BXI and W1TXT for the info about this site.

Remote Station Control

Here is a 12 minute video of how Randy K7AGE is using his laptop PC on the road to control his rig at home, operating on several modes and bands. Thanks to W4BXI and W1TXT for the link.

Saturday, October 25, 2008

Montgomery Hamfest

Date: Saturday, November 8, 2008
Time: 9:00 A.M. Until 3:00 P.M.
Location: Garrett Coliseum, 1555 Federal Drive, just West of Coliseum Blvd. in North Montgomery, AL
For more information, click here.
Bell Ringers planning to attend are invited to contact WA5MLF to share attendance plans within our group and coordinate an eyeball QSO.

Tuesday, October 14, 2008

Solar Cycle 24

This morning one of our members mentioned the SOLARCYCLE24 web site for a source of information about the progress of the new cycle. The appearance of sunspot #1005 seemed to bring some nice short-range propagation on 40 m yesterday, but its fading seemed to relegate us to the usual 200 mile minimum for our morning QSO today.

Saturday, October 4, 2008

Vintage Amateur Radio Stations

Visit this web site for recordings of 1920's era rigs. Photos of VE3BBN's spark-gap transmitter are included. Thanks to Brian N4DKD for letting us know about this site.

Thursday, September 18, 2008

Receiver Saver -- Updated Circuit

I've made two modifications to the circuit that is described in a posting on 6/10/08. Click on the revised schematic below for an enlarged view.

By changing the values of R1, R2, and C1 as noted, the transition from transmit mode (receiver grounded) to receive mode (receiver connected through to its antenna) takes about 1 second. A smaller value of C1 can be used for a shorter time delay. The transition from receive mode to transmit mode is still very quick, IF the transceiver control lead provides a low resistance to ground on transmit, thereby discharging C1.

This circuit change enables an operator using full break-in CW to use the circuit on a spotting receiver without having the circuit's relay chattering in time with each CW character transmitted. Since the status indicator LED has its own switching transistor Q2, it now transitions from red to green a fraction of a second after the relay switches from transmit to receive state. The values of R3 and R4 could possibly be adjusted to change this behavior.

Diode D8 was added to prevent the powered-off circuit from presenting a resistance-to-ground of about 1 megohm or less (R1 in series with base-emitter junction of Q1) to the transceiver control circuit. In one user's application this circuit was connected to the control lead from a transceiver to a linear amplifier. The amplifier apparently interpreted the resistance-to-ground of the receiver saver circuit as a transmit control command from the transceiver. The addition of D8 presents a much higher resistance-to-ground on the control lead that should prevent false keying of the linear amplifier.

Enhanced ARRL Document Services

Thanks to Tim WA4PTZ for calling attention to the new option for obtaining copies of past QST articles. ARRL members can now access online copies of articles from December 1915 through December 2004 via the ARRL web site. Articles from other publications, as well as QST, can be ordered as paper copies or on CD-ROM. The search feature continues to provide a convenient way of finding those past articles.

Friday, September 12, 2008

October 18 Tailgate at Rome, GA

The annual Tailgate, sponsored by the Northwest Georgia Amateur Radio Club, will be held on Saturday, October 18th. Details are available here.

Wednesday, August 20, 2008

Antenna Grounding & Lightning Protection

This has been a recent topic of interest in our on-air discussions. Many good references are available for understanding this subject and for developing a design specific to your station configuration.

A very good, concise starting point is a 2-page article in the August 2006 QST, page 48, titled A Down to Earth View of Station Grounds. This article includes the following link to additional information from the ARRL Technical Information Service. Included there are links to a 3-part article series Lightning Protection for the Amateur Radio Station, published in QST in 2002, that gives detailed design methods and devices for protective grounding. This and earlier articles are available as downloadable PDF files.

Additional web links are included at the ARRL Technical Information Service page for other published articles and commercially available protection devices.

This year QST published (February & April issues) a 2-part article titled Lightning: Understand It or Suffer the Consequences. This article goes into some depth about the behavior of ground systems when exposed to lightning events.

Other links that may be of interest are:
Tower picture gallery that shows details of one ham's tower grounding design
A tutorial on NEC Article 810 – Radio and Television Equipment

Feel free to post your comments here. You can post as anonymous or with your name / callsign, if desired. You do not need to have a Google ID to participate.

Huntsville Hamfest Photos

Several photos from the 2008 Huntsville Hamfest are now posted in the Bell Ringers group photo section. Thanks to W4UOA and W4BXI for capturing these views.

Tuesday, August 12, 2008

N9N Special Event

I've posted some audio recordings of the N9N special event station here. Also included is a link to the report by N4KC.

Morse Code Alive and Well

BBC News published this video report on the continuing popularity of CW among hams in the UK. Thanks to Joe KA4ZCO for notifying us about it.

Sunday, July 27, 2008

Huntsville Hamfest - August 16-17

Dear Bell Ringers, RVers, Mabellhams, and Friends attending
the Huntsville Hamfest on Aug 16th --

You are cordially invited to be present for the Bell Ringers Photo Op and 3rd Annual White Elephant Gift Exchange. Above is a group photo from last year. More of last year's photos are posted here.

Bell Ringers Photo Op - Sat Aug 16th

Meet At NOON inside the Building Entrance near the ticket desk.
Picture Taking at 12:10 Sharp! Don't be a minute late!
The 3rd Annual White Elephant Gift Exchange is for those in the photo.
(Bring any old thing wrapped in plain brown paper and put in box.
After the picture taking; grab a different "White Elephant" from the box).

73 and looking forward to seeing you
John Drum
Bell Ringer # 31

Nixa Hams Field Day

N0SAP is proud of the Field Day activities of the Nixa Amateur Radio Club. The club's web site includes some very nice videos from this year's and last year's Field Day operations. You can find them here.

A Ham's Paradise - KH6YY

For a visit to this dream facility on Oahu's north shore, click here. It has six towers and six full operating positions.

Tuesday, June 10, 2008

Receiver Saver Circuit

I recently assembled and delivered to W4BXI a customized version of a circuit developed by AD5X to permit the safe use of a secondary (spotting) receiver on its own antenna while operating a transceiver on a main antenna. The circuit is intended to protect the spotting receiver from excessive RF energy when the main rig transmits on its nearby antenna. The original circuit was published in the January 2008 issue of CQ magazine.

Here is a copy of the customized schematic, which adds a power switch, status indication LEDs, and supplementary protection elements.

Some views of the assembled unit are shown below.

W4BXI is testing this unit at his station, and I expect to incorporate some refinements as I get his feedback. One change may be to use shielded leads from the two SO-239 jacks to the circuit board, to improve the isolation between the receiver and the antenna when the receiver is grounded. Another change I am considering is the introduction of a time delay for restoring the antenna-to-receiver connection when the control signal changes to the receive state. A few seconds of delay here would minimize relay cycling if the operator is using full QSK, while not significantly affecting the utility of a spotting receiver.

Saturday, April 19, 2008

BirmingHAMfest - May 3-4

Zamora Shrine Temple, 3521 Ratliff Road
Bell Ringer gathering:
Saturday, May 3 at 1:00 pm in forum room #2
Contact: John WA5MLF

Thursday, April 17, 2008

WA9JNM -- Bell Ringer #322

Please welcome Steve WA9JNM as our newest member of the Bell Ringers. He is member #322. Steve is a frequent participant in our Saturday morning net and our weekday morning QSOs.

W4UOA presentation on Intermodulation Distortion and the 3rd Order Intercept Point

On April 14 Carl delivered this presentation to the Tuscaloosa Amateur Radio Club. Here is a photo taken at the conclusion of the session. W4BXI and WA5MLF attended, following a visit to Carl's hamshack

Photo from W0S Special Event

Here is a photo showing Sap along with visiting operators Fred and Smitty.
Additional photos are posted at a page of the Bell Ringers gallery.

Thursday, April 10, 2008

W0S Titanic Special Event - April 12-13

The Titanic Special Event takes place this weekend, April 12-13. You can find most of the essential details on the Titanic Blog.

The home page includes this link to a live video stream.

Sap advises that the weather will again be frigid for this event. We hope that Fred & Smitty will enjoy operating the station under authentic Titanic conditions.

Friday, March 28, 2008

S-Meter Ham Radio Website

You may find this web site of interest. It was suggested a while back by Smitty. Here is a quote from the home page:

"Check your signal and listen to others on remote receivers. Read thousands of pages of ham radio information. Download virus-free radio-related design programs. There is no charge for receiver usage, any of the information, or any downloaded computer programs."

Sunday, March 23, 2008

Updated Links

I have updated the Bell Ringers links page with some new content and some regrouping of existing content. Let me know if you have other links / topics that you'd like to see displayed there. I consider it to be a repository that will be updated infrequently while serving to complement the dynamic content of this blog.

In the green box to the right I have spotlighted a free open-source program - QUCS - that I enjoyed using recently to produce some neat and easy-to-revise schematics. I'm also learning to use its powerful circuit simulation capabilities. I have used both the Windows and Linux versions of the program. Contact me if you'd like more information.

Another program for you to check out is the 4nec2 Antenna Modeler.

73, John

Monday, March 10, 2008

Member page updates

The following member pages have updates:
KE4ID - 2 new photos
N4DB - web site link

VP6DX - Ducie Island - 2008

This recently concluded DXpedition has a nice web site that details the location, equipment, and operators, as well as the contacts.

Community funding request at Nixa

WA0SAP shares this request to help fund a community project that would establish a ham radio station at the Nixa Fire Department for training and emergency communication.

C.R.E.S. Amateur Radio Club

W4BXI directs us to the web site for the Columbus Radio Enthusiasts Society Club ....
He says:
"lots of hams in on CQ WE and CQ TP
The WE facility is about sold; latest product was making Cell Phone Hub sites (repeaters?);
you have seem some of these prefabricated buildings being transported up and down the interstates on flat bed trucks ..."

Dalton Hamfest

Selected photos from W4BXI taken at the Dalton, GA Hamfest are posted in the Group Photos section of our website. The group photo is from Ed Ringer W4DGH and Hjordis KI4TVB.

Thursday, February 28, 2008

W0S Titanic Special Event

WA0SAP reports that preparations are underway for the second annual special event on April 12-13 at the Titanic Museum in Branson, MO. This will honor the efforts of the two radio operators aboard the Titanic on April 14, 1912. This year marks the 96th anniversary of the Titanic's sinking, and annual events are planned leading up to the 100th anniversary. For information about the special event, click here.

Monday, February 11, 2008

Gadgets Gab at 60 GHz

See this article to read about benefits and challenges of using a section of unlicensed spectrum at 60 GHz to provide wireless communication among our favorite gadgets.

Thursday, January 31, 2008

Hand Made Tubes

Have you ever seen a triode vacuum tube made by hand? Visit this web page and scroll down to the 17 minute video of the process.

On a related theme, you might like the hand made cathode ray tubes shown here. A short video of one in operation is shown here.

Monday, January 14, 2008

Storm Spotters in Missouri

WA0SAP advised that this article discusses the storm spotting activities of radio amateurs near Springfield, MO during the January tornado outbreak. The article is titled "Risking all to warn others".