Author Archives: Robert Shank

Advice from multi-station operators on how to minimize intermodulation and RFI. Conrad Trautmann, N2YCH ARRL Technical Editor, Keith Elliott W6KME Contributor and Member VCARC and CVARC ARRL Field Day in California Now, let’s apply these principles to your club’s Field Day operations, or to any multi-station portable operation. Keith Elliott, W6KME, from the Conejo Valley Amateur Radio Club, AA6CV, in southern California has successfully run Field Day for his club for 3 years using 23 stations that are able to operate at the same time. Antennas Keith maximizes use of the space allowed in the Field Day rules and selects antennas that will provide maximum isolation between one another, providing good signals aiming north/northwest. By lining up the three identical HF antenna arrays end to end, the nulls at each end of the dipoles aim at each other, minimizing the amount of RF getting into the adjacent array. They use… Continue reading →

A little over a year ago I started hunting for the title of this article.   It is as its name implies it is a DC voltmeter good down to about 20ppm.  I’ll talk about it some after giving you some of the backstory.  I’d been looking one to acquire for well over a year.  A few months ago, I found one, bought it and promptly found out I got scammed.   Got my money back though.  A second stroke of better luck in November proved more productive.  I located a 58-year-old example in Berlin Germany (viz a viz the Max Planck Institute) for a reasonable price.  That’s not to say there were no hurdles.  The seller didn’t want to ship to the USA.  Bribing the man made him agree to shipping it.  Once shipped it had to tediously wend its way through Germany, endure a flight to New York, languish for… Continue reading →

By Clement Alberts KM6OKZ I recently wrote a little article about my adventures with the Tek 577 curve tracer that Robert Shank KM6RSS was kind enough to sell me.  Recall for a moment that the 577 was designed to be used with semiconductor devices.  In my case, I wanted to look at the four 7838 pentode power output tubes on the Fisher 400 stereo amplifier my father gave me back in 1968 (that being an entire project in itself).  The 577 is capable of supplying control sufficient grid and plate voltages to power the 7868-vacuum tube.   It cannot however supply a separate voltage to power either the screen grid or the filaments.  The filaments were simply powered by DC supply.  The screen grid required my obtaining a HP 6515A power supply. This adjustable little joker can output almost 2KV.   The screen grid only required 350V.  The only thing I didn’t… Continue reading →

On October 1, 1920, Scientific American magazine reports that the rapidly developing medium of radio would soon be used to broadcast music. A revolution in the role of music in everyday life was about to be born. “It has been well known for some years that by placing a form of telephone transmitter in a concert hall or at any point where music is being played the sound may be carried over telephone wires to an ordinary telephone receiver at a distant point,” began the bulletin in the October 1, 1920 issue of the popular science monthly, “but it is only recently that a method of transmitting music by radio has been found possible.” In an 1888 novel called Looking Backward: 2000-1887, author Edward Bellamy imagined a scene in which a time-traveler from 1887 reacts to a technological advance from the early 21st century that he describes as “an arrangement… Continue reading →