HF Digital Modes: JT65

An article in the May 2012 QST (page 44) highlights JT65, an HF digital mode that is seeing strong growth. Its main appeal seems to be that it enables contacts at very low signal levels (using low transmit power and simple antennas). This is a result of its being developed for meteor scatter and EME communication. The digital protocol and software were developed by Nobel laureate Joe Taylor K1JT whose web site devoted to weak signal communication provides background.

A while back Jorge NN4QQ made us aware of WSJT software being used to test propagation paths (Weak Signal Propagation Reporter) and to populate a database and map - WSPRnet - that is available for viewing by anyone on the Web.

A special HF Digital page from ARRL provides links to information, software downloads and audio samples for JT65 and several other digital modes, including the ever popular PSK31.

A Windows version of the JT65 software was developed by Joe Large W6CQZ and is available at the HF Digital page. A brief web search shows that Mac users are also running JT65 via two options:

• Compiling WSJT software to run on a Mac
• Running the Windows version under WINE or Crossover

For details see this Google Groups posting or this Yahoo Groups posting. Many other applicable results can be found by searching with "JT65 Mac". Of course, Linux can also run this software.

Special Event Stations: 100 years since Titanic sinking

Many special event stations this month are observing the 100th year since the sinking of the Titanic (14 April 1912), commemorating the role of radio in reporting the event and summoning of help. Here are a few of the web sites that provide information, including dates, times, frequencies:

• Remembering Titanic MGY
  Includes many photos
• W0S Titanic Special Event
  Located at the Titanic Museum, Branson, MO, this station is a favorite of N0SAP.
• W4S Special Event
  At Pigeon Forge, TN

 On a related note, the article The Titanic's Role in Radio Reform tells how the Titanic sinking triggered a century of radio improvements. A sliding timeline brings a series of 29 short stories or profiles of events and developments.

QST Product Review Summary

N4KC shared this summary of QST Magazine product reviews for HF transceivers or receivers.  It provides a nice color-coded table with key measurements.

Thanks, Don!

March 8-9 Solar Events

The snapshot above tells the story of what propagation was like on March 9. We noticed much weaker than normal signals on 75 m during our morning QSO. Others reported 40 m to be weak, too. I have not heard about the upper bands.

Here are two of the many links that describe the flares and CMEs:
Biggest solar storm in years
Solar storms ramp up

Bell Ringers at BirmingHAMfest

Bell Ringers and friends gathered at the BirmingHAMfest on March 3. See the photos here.

VoIP Roundtable on 60 m

This morning we started on 75 m, with a few (remote or mobile) members of our group connected via Skype to Carl's rig. This used the VoIP HF roundtable arrangement that Carl perfected and documented a few years back (QST September 2009). When propagation faded to marginal levels, it was suggested that we try 60 m. Since several of us do not have 60 m capability, we were added to the Skype roundtable conference call that Carl had in progress. Below is a screen shot from my PC showing the 7 parties (plus myself) connected on Skype, along with a view of our chat room text on the left. Click on the image below for a larger view.

Carl continued the roundtable on 60 m with 3 other stations while the rest of us shared his rig via Skype.

Thanks, Carl!

A single-transistor 16 dB gain RF amplifier

Here are two photos of an RF amplifier built by KE4ID using the popular bug construction. (Click on each image to enlarge.) The use of a readily-available metal box saves cost and provides a convenient ground plane to which components can be directly soldered for grounding and mechanical support. The circuit is based partly on designs published by KK7B in QST and in the ARRL book Experimental Methods in RF Design.

Jack loaned this amplifier to me for evaluation as an interface between a stand-alone Yaesu digital VFO and my Heathkit SB-104A transceiver. I'm in the process of breadboarding a similar unit for this function. The output of the Yaesu VFO needs to be boosted to 3 V p-p to match what the Heathkit internal VFO provides. An existing jack for an external VFO makes the connection to the Heathkit convenient. The goal is to obtain a more stable and precise frequency control than what is possible with the internal analog VFO.

Here is the schematic diagram.(Click to enlarge.)