Many thanks to SWLing Post contributor, Mario Filippi, who writes:
Schulman auctions is now live with the latest batch of ham and other radio equipment. Lots of interesting radios available.
https://schulmanauction.hibid.com/
Thank you for the tip, Mario! Some amazing variety in this latest auction!
Many thanks to SWLing Post contributor, T.D. Walker, who shares the following:
In 2019, I put together the first two episodes of Short Waves / Short Poems, a program that featured voices of poets on shortwave radio. Since last year, I’ve been trying to put together a full season of the show, but the pandemic has left me with far less free time for radio projects than I had before.
Thus, I’m reaching out to ask for volunteers who would be interested in helping out with tasks related to Short Waves / Short Poems and another program for shortwave radio that I’m working on.
I have the content and sound editing lined up, but I could use some help with just about everything else, including publicity, administrative tasks, and getting another set of ears on the shows before broadcast.
If you’re interested, please email me at info [at] tdwalker [dot] net. More information about the past episodes can be found at shortwavesshortpoems.com. Thanks!
Many thanks for the message and it’s great to hear there’s another season in the works. Readers, if you can help in any way, feel free to reach out to her. We’ll certainly plug the season and episodes here on the SWLing Post!
Many thanks to SWLing Post contributor, Jeremy Clark (VE3PKC), who writes:
Thomas:
Got kind of nostalgic [last week] as it was Thanksgiving Day in Canada. I did a video about my Hammarlund HQ100AC which I got for a Christmas present in 1964, 57 years ago. It still works!
Best Regards
Jeremy Clark VE3PKC
Click here to view on YouTube.
This is wonderful, Jeremy. There’s simply nothing like our boat anchors and vintage radios that continue to work perfectly and pump out amazing, warm audio. There was no such thing as “planned obsolescence” back then! Our radios like the HQ100AC will long outlast us!
Thanks again, Jeremy! I hope your HQ100AC enjoys a even more time on the air and keeps you warm this winter.
OMI Cryptograph, an Italian cipher machine built by Ottico Meccanica Italiana (OMI), is part of the National Cryptologic Museum’s (NCM) collection of artifacts. (Photo by NCM)
Many thanks to SWLing Post contributor, Andrea Borgnino, who shared the following news from the NSA Museum (the National Cryptologic Museum) in Fort Meade:
FORT MEADE, Md. — At the outbreak of WWII in 1939, Nazi Germany’s Enigma encryption machine stood as the state-of-the art method for sending and receiving secret messages. It wasn’t until 1940 that English mathematician Alan Turing, and the team at Bletchley Park, cracked the daily changes Berlin made to its cipher system, and helped the Allied powers win the war.
While the Enigma stands out as the most famous of encryption machines, Italy, set out to develop a high-end machine to rival its war partner, Germany. In 1939 Italy’s government secretly tasked a little-known photogrammetric equipment company, Ottico Meccanica Italiana (OMI), to build a device capable of rivaling its more famous cousin. Founded in 1926, OMI’s tools were used to create precision topographical maps and surveys using stereoscopic aerial photography. The technical expertise made OMI a natural fit for the job. The end result was OMI’s first cipher machine known as the Cryptograph Alpha.
OMI built cipher devices throughout WWII, and into the 1960’s, including: the OMI Cryptograph, the OMI Cryptograph-CR and the OMI Cryptograph-CR MkII. While many of these devices managed to survive passing through the hands of various collectors and museums, examples of the second iteration, the OMI Cryptograph machines, were widely believed to have been destroyed long ago. Until now. Digging through its vast collection of warehoused artifacts, the National Cryptologic Museum (NCM), curators found an OMI Cryptograph machine in its collection.
NCM Collections Manager Spencer Allenbaugh recently discovered the OMI Cryptograph in a dusty crate and immediately knew he had found a treasure.
“This find gives the National Cryptologic Museum the chance to recover an artifact once thought to be lost forever. This device provides a small glimpse into Italy’s cryptologic history and how Italian cryptologists operated during that time period. This recovery also strengthens our already-strong reputation in the field of cryptologic history and will give people more reason to come and see the device up close once the museum re-opens,” said Allenbaugh.
“When the device is on display, researchers and historians will have the opportunity to see the artifact, study it, and learn more about its history and design,” he added.
Originally introduced around 1954, the OMI Cryptograph operated similarly to the German Enigma, with five moving cipher wheels to encipher/decipher messages, but, unlike the military Enigmas, it also had a built-in printer that produced its output directly onto a paper strip. This model was operational until the late 1950s when the OMI Cryptograph-CR succeeded it.
Visitors to the NCM can look forward to see this treasure on exhibit when museum renovations are completed and the museum reopens in Spring of 2022.
Figure 1. A Passive, Resonant, Transformer?Coupled Loop Antenna for Shortwave
Many thanks to SWLing Post contributor, Bob Colegrove, for the following guest post:
By Bob Colegrove
Over the years I have resisted the level?of?effort necessary to construct and maintain outdoor antennas. Rather, I have focused on squeezing out all of the microvolts I could get inside the house. Many years ago I had access to a well?stocked engineering library, and used my advantage to gather information about the theory and development of loop antennas – a daunting undertaking for an English major. Ultimately, by adhering to a few basic rules, some of them dating back 100 years, I found quite acceptable performance can be had with an indoor passive antenna intersecting just a few square feet of electromagnetic energy.
There are a couple of advantages of resonant loops as opposed to non?resonant ones. The first is the fact that the signal dramatically increases when you reach the point of resonance. The second follows from the first in that resonance provides a natural bandpass which suppresses higher and lower frequencies. This gives the receiver a head start reducing intermodulation or other spurious responses. The downside of all this is that the resonant loop is, by design, a narrow?band antenna, which must be retuned every time the receiver frequency is changed by a few kHz. On the other hand, there is nothing quite as rewarding as the sight (S?meter) and sound you get when you peak up one of these antennas – you know when you are tuned in.
There is nothing new about the loop antenna described here. It’s just the distillation of the information I was able to collect and apply. There are a number of recurring points throughout the literature, one of which is the equation for “effective height” of a loop antenna. It basically comes down to the “NA product,” where N is the number of turns in the loop and A is the area they bound. In other words, provide the coil with as much inductance as possible.
Unfortunately, for resonant loops, the maximum coil size diminishes with frequency.
With this limitation on inductance, the challenge becomes minimizing unusable capacitance in the resonant frequency formula in order to get the highest inductance?to?capacitance (L/C) ratio possible. Some of the unusable capacitance is built into the coil itself in the form of distributed capacitance, or self?capacitance between the coil turns. This cannot be totally eliminated, but can be minimized by winding the coil as a flat spiral rather than a solenoid, and keeping the turns well separated.
The second trick is with the variable capacitor. Even with the plates fully open, there is residual capacitance on the order of 10 to 20 picofarads which can’t be used for tuning purposes. A simple solution is to insert a capacitor in series, about 1?4 the maximum value of the variable capacitor. This effectively decreases the minimum capacity and extends the upper frequency range. In order to restore the full operating range of the variable capacitor, the fixed capacitor can be bypassed with a ‘band switch.’ With the series capacitor shorted, the variable capacitor operates at its normal range and extends coverage to the lower frequencies. Continue reading
(Source: University of Sydney)
International student Ziteng Wang detected unusual signals from deep in the heart of the Milky Way using CSIRO’s ASKAP radio telescope. Now astronomers are on the search for more evidence of what type object could be emitting them.
Astronomers have discovered unusual signals coming from the direction of the Milky Way’s centre. The radio waves fit no currently understood pattern of variable radio source and could suggest a new class of stellar object.
“The strangest property of this new signal is that it is has a very high polarisation. This means its light oscillates in only one direction, but that direction rotates with time,” said Ziteng Wang, lead author of the new study and a PhD student in the School of Physics at the University of Sydney.
“The brightness of the object also varies dramatically, by a factor of 100, and the signal switches on and off apparently at random. We’ve never seen anything like it.”
Many types of star emit variable light across the electromagnetic spectrum. With tremendous advances in radio astronomy, the study of variable or transient objects in radio waves is a huge field of study helping us to reveal the secrets of the Universe. Pulsars, supernovae, flaring stars and fast radio bursts are all types of astronomical objects whose brightness varies.
“At first we thought it could be a pulsar – a very dense type of spinning dead star – or else a type of star that emits huge solar flares. But the signals from this new source don’t match what we expect from these types of celestial objects,” Mr Wang said.
The discovery of the object has been published today in the Astrophysical Journal.
Click here to read the full article at the University of Sydney.
Many thanks to SWLing Post contributor, Mark Hirst, who writes:
Thomas,
I’m currently enjoying ‘Chicago Fire’ on Netflix and spotted this scanner at the fire station.
Taking a wild guess, I typed ‘realistic scanner’ into image search and eventually found one that looked similar, the Realistic Pro-57.
Perhaps scanner enthusiasts can confirm this, and maybe share some memories about it, good or bad!
Thanks for sharing this, Mark! Certainly not an easy scanner to ID from such a quick video frame, but I’m willing to bet some of our readers can comment and confirm the model and share any thoughts about this particular scanner!