Category Archives: Radios

Guest Post: Backpack Shack 3 – Part 2

Many thanks to SWLing Post contributor, TomL, who shares the following guest post as a his Backpack Shack 3 evolves:


Backpack Shack 3 – Part 2

by TomL

Wanting MOAR options for my recent amplified whip antenna experiment, I decided to add a second antenna input to the kitchen cutting board (can I call it a “Breadboard”? – Ha, that’s an electronics joke!).  The idea behind it came from realizing that I might not want to spend all my time outside at a picnic table or on the beach, especially if it is drizzly and windy. And I still wanted a better ground for the antenna.  So, I thought I could use more Trucker Parts and put an antenna on top of the roof of my vehicle so I could listen in the relative comfort and safety of my small SUV (or even a friend’s car).

Breadboarding

Here is the crowded “Breadboard” with some extra items added.

I thought of the vertical antenna as a short longwire and had an old, original RF Systems Magnetic Longwire Balun.  That device allows for an improvement in signal/noise ratio (in theory) if used on a longwire. Perhaps it works on this, too??  You can see the gray cylinder connected right beneath the trucker mirror mount on the left (this will not be tested at this time, see External Antenna below).  The output goes to a greenish Daiwa switch on the right.

A large amplified antenna has the real possibility of overloading the amplifier.  With the Magnetic Balun, I am hoping the VHF band is attenuated enough to preclude any problems because its response naturally tapers off past 40MHz.  But Mediumwave is well within its bandpass. I remembered an old Kiwa Electronics Broadcast Band Rejection filter not being used for a long, long time, so I connected that right after the Daiwa switch (the metal box with red plate).

This output then goes to an RF choke just before entering the pre-amp.  I figure I will be using my SDRPlay RSP2 and noisy laptop and wanted to try to reduce any interference traveling on the outside coax braid before it gets amplified.

External Antenna

OK, now for the other Daiwa switch selection.  The external antenna will be connected and disconnected as often as I use it.  I attached two right-angle coax adapters to be the connection point for the antenna.   This is so that the physical switch threads do not have to handle that wear-and-tear. You can see it as the fuzzy out of focus thing sticking up out of the left side switch position.

The wire going out the top of the Breadboard goes to a Firestik K-11 magnetic mount placed on top of the roof of the SUV.  I also wanted this to be connected to a magnetic balun. I just happened to have a nearly unused Palomar Engineers Magnetic Longwire Balun.  It has its own ground lug for use with a counterpoise. Temporarily, I left the 18 feet of wire that came attached to the K-11 Mount and attached an adapter and BNC test lead; on the other end is connected the spade lugs to the Balun (red wire to the lanyard nut, black wire to the ground lug).  It all fits neatly inside a Sistema 3 liter container.

The magnet and box self-clamp easily onto the roof of the vehicle.  I added a new 18 inch section to the Trucker Antenna Shafts creating a full 72 inch antenna, complete with mag mount, ground plane (car body), and magnetic balun.  It is very easy to put up and take down and the box helps keep everything contained.

I am pushing things a bit here.  Magnetic Baluns are not really meant to be used on vertical antennas.  It probably breaks some sort of Cosmic Electrical Law somewhere that causes electromagnetic waves to get very confused and die a horrible, twisted, circular death.  But I figure that it is an unbalanced “line” similar to a longwire antenna; it’s just a little short and goes straight up instead of horizontal! I like the idea, so I am going to run with it.

Warnings!

It goes without saying that the Antenna Shafts, magnet mount, and magnetic balun are weatherproof (but NOT lightning proof!).  Take proper lightning precautions and take it down.  Even so, I might add a small drainage hole to the box since it did rain a tiny bit during testing.

Secondly, this setup is ONLY FOR STATIONARY VEHICLES!!!!  DO NOT TRY TO DRIVE DOWN THE ROAD OR HIGHWAY!!!! The magnetic mount will NOT stay on the car and will damage your vehicle and maybe a vehicle travelling next to you!

Performance

As you can see from the picture, my new Tecsun S-8800 is getting a workout while connected to the Cross Country preselector (not shown behind it) and to the backpack next to the back seat window.  The Tecsun S-8800 is a nice radio. My copy has a couple of quirks that I might have to send it back (the AM band tunes incorrectly 2 kHz lower than it should and the SW SSB tunes 140 Hz higher than indicated and I have to compensate using the fine-tuning dial for these modes–FM seems correctly tuned).

Other than this, the actual performance is really quite good!  DSP does have sharp cutoffs to the IF bandwidth (especially resolving strong station interference when selecting 3 kHz vs. 4 kHz).  With all my filters/balun/choke, I did not notice any MW or FM breakthroughs and signals on those bands were nicely contained and “normal”.  Interference from my cell phone while looking up internet frequency listings was minimal – seems like the cable shielding, choke, and car roof are doing a good job.

The audio output jacks have very thin clearance between the jacks and the housing of the radio. So for the second time, I will not have recordings since the cable I wanted to use has home theater style construction with very thick plug outer connectors and will not fit!

From an RF-quiet “Forest Preserve” (County park), there were a variety of stations received from the 25 through 19 meter bands (Local time 11am-1:30pm). A few stations I have never heard before until now:

  • Radio Free Asia in Korean on 11985 KHz (Tinian Island)
  • Radio China International in Esperanto on 11650 KHz (Xian China)
  • Radio Farda in Persian on 12005 KHz (Wooferton England) – broadcast opposite my direction
  • Radio Bible BCI in Somali on 15310 KHz (Nauen Germany) – Strange sounding but interesting  Christian Somali music
  • Radio Free Asia in Chinese on 13675 KHz (Dushanbe Tajikistan)
  • Voice of Hope Africa in English on 13680 KHz (Lusaka Zambia) – had to use ECSS USB to get away from strong interference from RFA on 13675, fairly good intelligibility (including music)!  I wish there was a 6 KHz option for SSB mode since the audio was slightly muffled and could not compensate much with the tone controls. That kind of feature usually comes with radios costing 3X more, however.
  • Voice of Korea in French (Kujang North Korea) being squashed by Radio China International (Kashi China) in English on 13760 KHz

It was so nice not to be on a beach and have people walk by STARING at me with my weird radio/antenna setup.  And I was dry and comfy sipping a cool drink while there was a drizzle of rain pelting the windshield. Downside might be that the car setup cannot always be located optimally if I want to be next to that Very Large Body of Water (Lake Michigan) to help enhance reception but this is not a bad alternative.   The next test will have to be during early evening when signals are booming into my location and see if performance holds up under those conditions!

Happy Listening,

TomL

Modified Parts List

Parts Repeated from Part 1 article


As always, Tom, a most impressive setup powered by home-grown ingenuity! Thanks so much for sharing the evolution of your field kits with all of us here at the SWLing Post!

By the way, you still have me chuckling about your use of the term, “breadboard!” 🙂

Self-powered shortwave radio spotted in Battlestar Galactica


Many thanks to SWLing Post contributor, Bruce F, who writes:

Here is a photo of a radio from the 2004 – 2009 TV series “Battlestar Galactica“. This radio is perhaps unique and worthy of careful study! Why? Because not only was it NOT MADE on Earth, but there is no connection in its design with any other known radio ever.

The reason for this is quite simple. This sci-fi TV series takes place in a distant future when all humans had left the Earth generations ago and migrated throughout the galaxy. The humans in this series have lost all touch with humanity’s origin planet. They do not know where Earth is, or even if it still exists, or if it ever actually existed.

“Earth” is an important part of their religion and mythology. So here is a totally un-Earthly radio. Odd though. it does closely resemble a Grundig wind-up radio I owned sometime in the 2000’s…

Ha ha! Yes indeed, Bruce. And I can confidently say that I’ve personally distributed hundreds upon hundreds of this particular radio model for Ears To Our World. Grundig used to market it as the Grundig FR-200, and Tecsun still offers it as the Tecsun Green-88 (or GR-88). It’s a brilliant receiver, although I’m not sure how effectively one can monitor shortwave while in a spacecraft! 🙂

I also grabbed some screenshots from BSG with a number of radios some time ago. I’m not sure I ever posted it, though. I’ll have to look through my (rather deep) drafts folder.

Thanks for sharing, Bruce. I’ll add this post to our growing archive of radios in film!

Video: N1SPY builds and describes the components of a simple receiver

Many thanks to Thomas Cholakov (N1SPY) who shares the following video where he explains how radio receivers work and builds a radio receiver:

Click here to view on YouTube.

As always great video, Thomas! Keep up the good work!

Hospitals and RF noise: FM and HD radio’s strong suit

The Sangean HDR-14 AM/FM HD radio

For the past week, I’ve been away from home spending time with my mother at the hospital while she recovers from a surgery. I’ve got a number of reviews and evaluations in the pipeline, but thankfully no shortwave or HF radios on the table this week (although the ELAD FDM-S3 and CommRadio CTX-10 are just around the corner). Listening to shortwave (or even mediumwave) in a hospital room can be an exercise in futility–there are just too many devices emitting noise and the buildings are built like bunkers with incredibly thick walls to attenuate signals.

I’ve had the little Sangean HDR-14 with me, however, and have been very pleased with its ability to snag FM stations both analog and digital. I’ve also had fun discovering a surprisingly diverse FM landscape in this metro area. I haven’t snagged an AM HD station yet, but my hope is one evening I might DX one (fingers crossed and not holding my breath).

The Sangean HDR-14 (left) and CC Skywave SSB (right)

At the end of most days, I’ve been able to catch a little shortwave action with my CC Skywave SSB (pre-production) portable at the guest house where I’m staying. The evenings have been surprisingly peaceful here with only the occasional popup thunderstorm to insert a little QRN in my listening sessions.

Last night, while listening to jazz on FM, I finished reading All The Light We Cannot See by Anthony Doerr (affiliate link).

We’ve mentioned this book before and I know of at least dozen SWLing Post contributors and friends who’ve personally recommended it to me.

It is a superb novel and will, no doubt, tug at the heart strings of any radio enthusiast or WWII history buff. Highly recommended!

Indeed, last night I couldn’t fall asleep until I finished the book around 12:30 AM!

And mom? She’s recovering quite well and we hope will be discharged from the hospital soon.

Raspberry Pi Vintage Radio

This project was a winner in the Maker Share Mission May contest. While not strictly shortwave, of course, many of SWLing Blog readers enjoy, as I do, all things radio, and especially creative and new expressions of radio. Here is a brief excerpt from the MakerShare posting:

Vintage radios are fascinating. At one point the radio was the main method for mass communication of news and entertainment and was manufactured in a variety of styles to be prominently displayed in a home. Unfortunately, many vintage radios that have been physically preserved no longer function and it is impractical for them to be repaired. Described is the design and implementation of the Raspberry Pi Radio (RPiRadio), a device that bypasses the analog electronics of a vintage radio and digitally recreates the behavior of a vintage radio that is able to be tuned to vintage radio programming.

The whole posting may be found here, with extensive details on the building of the radio and how it was programmed for sound replicating the vintage radio era.

While I love tinkering with old radios and trying to bring them back to life, some radios are just beyond reasonable repair. This can bring old radios back to life in a way which seeks to honor their past – a very cool idea indeed!

Robert Gulley, AK3Q, is the author of this post and a regular contributor to the SWLing Post.       Robert also blogs at All Things Radio.