Monthly Archives: March 2014

EchoLink and IRLP Repeater Remote Access with a Raspberry Pi — Presentation

We have another interesting presentation lined up for our April 7th meeting. Don Fraser WA9WWS will show us how an inexpensive Raspberry Pi based node supporting either or both protocols, EchoLink and IRLP, can enable Hammin Sams members to remotely access the Hammin Sams net. This way, members could participate in their Hammin Sams net activities while out of town.

Greg Cook, you will remember, described Raspberry Pi configurations at our meeting last month. You can locate reference material about that presentation in the Technical Interest category on this site (see sidebar at right).

This time he focuses on a need that Hammin Sams members have expressed on net. Applicability is not limited to Hammin Sams nets, though, making this a must attend event for anyone curious about practical use of these protocols or about Raspberry Pi applications.

See you there!

Repeater Pairs


Ever find yourself confused, even momentarily, about the frequencies your radio uses to work a particular repeater? Come on now, admit it, I have on occasion. So let’s review how repeater frequency pairs are specified and correlate them to your radio. This material relies heavily on the section headed Frequencies on the Wikipedia page

Download Repeater Pairs as PDF

Let’s get a clear picture in our minds of what is happening. The basic relationship to fix in our minds with regard to repeater pairs is:

  • (+) offset means the Repeater Receives on a frequency Above the one it Transmits on, think +RRAT as a mnemonic
  • (-) offset means the repeater receives on a frequency below the one it transmits on
  • Operator’s radio displays the frequency its receiver is tuned to
  • Offset amount — disregard the negative sign if there is one. Engineers refer to this as the absolute value or magnitude of the quantity between those vertical bars. The offset amount is the separation between the RECEIVE and the TRANSMIT frequencies.
  • Offset direction accounts for the sign, positive as pictured in the diagram here, negative if reversed

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Vintage DSL Card Images Available

Trove of Vintage Ham Radio Photos, QSL Cards

The grandson of Thomas “Tom” Russell Gentry, W5RG (SK), has developed a website that is certain to be of interest to vintage radio enthusiasts. Don Retzlaff, who is not a ham, said his grandfather was among the earliest Amateur Radio operators, getting his license in the early 1920s — at one point identifying as NU5RG — and remaining active until he died in 1979. The W5RG call sign has since been reissued.

Tom Gentry, W5RG (SK), at his station in an undated photo.

“He collected QSL cards from other amateur operators all through his life,” Retzlaff said of his grandfather. “In recent years I became interested in those cards and my grandfather’s hobby.”

With the help of his father Donald Retzlaff, W5MIY, Retzlaff located all of the QSLs — some 5700 in all — as well as other memorabilia documenting his grandfather’s ham radio activities and his time in the Army Air Corps shortly after World War I. He painstakingly scanned both sides of each card along with dozens of photos of now-vintage stations — many with operators — that his grandfather had collected and posted them all on a website dedicated to his grandfather and his life as an Amateur Radio operator.

Among other features, the site offers an opportunity to leave comments. “This has definitely been a labor of love,” said Retzlaff, who retired this year as a Principal Lecturer in the Computer Science Department at the University of North Texas.

— Thanks to The ARRL Letter for March 6, 2014

AC0NK’s DIY Pointers to ARRL Content

Bill AC0NK provides these two pointers for DIY enthusiasts, both sources to very fine ARRL content.

This first is about the Dayton HAM Festival in Dayton, OH. If you’ve never been there, you are missing something nothing short of mind boggling.

This second is a link to ARRL’s DIY page, where you’ll find articles, ideas, and pointers to pique the interests of anyone young or old: The DIY Magic of Amateur Radio