Category Archives: Ham Radio

M.I.T. Radio Society: Public lectures covering all aspects of radio

Many thanks to SWLing Post contributor, Jennifer Waits, who notes that The Massachusetts Institute of Technology Radio Society (W1MX) and the Department of Electrical Engineering and Computer Science (EECS) are presenting a series of radio-related lectures covering a wide array of topics, “from the design of modern wireless communications systems and 5G, to software defined radio and satellite communications, to shortwave radio propagation, space weather, Radio Astronomy and more.”

The public lectures are announced here: http://student.mit.edu/iap/ns313.html 

All lectures are streamed live and archived on YouTube.

Jennifer notes that one of the most recent lectures focuses on shortwave radio and propagation:

Click here to watch on YouTube.

Click here to view the entire lecture playlist.

Thanks for the tip, Jennifer!

Spread the radio love

Dave notes the Icom IC-735 makes an appearance in “Pole To Pole With Michael Palin”

Many thanks to SWLing Post contributor, Dave Zantow (N9EWO), who writes:

Now you just just had to talk about the Icom IC-735.

In the final episode from the 1992 BBC 8 part series “Pole To Pole with Michael Palin” (Bitter End), you will see a couple of IC-735’s used.

They are located about 7:04 and 28:08 (minutes) in the video:

https://www.dailymotion.com/video/x2iszgj

Click here to view the video in a separate window.

Thanks for sharing this, Dave. I absolutely loved this travel series and watched it many years ago.  I’m also a big fan of Michael Palin. I think it’s time to re-watch it especially knowing the IC-735 makes a cameo!

Spread the radio love

Any reviews of the HanRongDa HRD-737 portable radio?

Many thanks to SWLing Post contributor, Jamie Anderson (KM4WYO), who writes:

I have been browsing around eBay too much and was trying to put together a do-it-all radio for camping/backpacking that is small.

It is hard to find SW/broadcast/weather/air band together (for good reason, of course). I did run across this radio that is interesting: the HRD-737 which retails around $40.

  • Internal 700mah 3.7v lithium, with 5v usb charge
  • Air 118-138 MHz
  • FM 87.5 – 108 MHz
  • AM 520-1720 kHz
  • CB 25-28 MHz
  • SW 2-30 MHz in 5 kHz steps
  • VHF narrow/wide FM – 30-223 MHz (10,6,2,220)

I’m not sure if it would pick up NOAA stations as I think they have a slightly different FM bandwidth.

It seems interesting for a do it all point of view, you could possibly monitor ham repeaters on 2 meters, just a little too short of frequency coverage for 220.

Click here to view the HDR-737 on eBay.

Have you seen one of these or something similar in your reviews?

I have never used the HDR-737, but thanks for bringing it to our attention, Jamie!

I should think, assuming the stated VHF frequency coverage is correct, that you should be able to hear weather radio on this receiver. NOAA weather frequencies are on 162.400, 162.425, 162.450, 162.475, 162.500, 162.525, and 162.550 MHz.

The manufacturer isn’t clear about the frequency steps on VHF however–it’s possible tuning increments could be too coarse to get a good lock on the station. That specification is omitted altogether even though every other band has stated frequency steps.

I should mention that the original C. Crane CC Skywave meets all of your specifications save the ability to potentially tune in the 2M ham radio band.

Post readers: Is anyone familiar with the HanRongDa HRD-737?  Please comment!

Spread the radio love

The NSA’s Software Defined Radio application “RedHawk” is now open source

Many thanks to SWLing Post contributor, Andrew, who writes:

Not kidding, a friend told me that NSA released a bunch of software to open source, the main list being here:

https://code.nsa.gov/

While looking at the list of projects on that page, halfway down the page, I found a project called “RedHawk” which is described as:

“A software-defined radio (SDR) framework designed to support the development, deployment, and management of real-time software radio applications.”

Now, being curious I opened the github link:

https://github.com/redhawksdr

[It] contains quite a number of subprojects, modules and other stuff, then I checked the main “RedHawk” project:

https://github.com/RedhawkSDR/redhawk

Here’s the documentation:

https://redhawksdr.github.io/Documentation/index.html

It seems really interesting; apparently it allows to define a wealth of processing stages (e.g. filters, converters…) and connect them to process signals coming from an SDR; I think it may be a very interesting and useful tool to fiddle/experiment with SDR receivers, if I’m not wrong it may allow to push an SDR to the limits, improving its performance, and may also be useful to write SDR software!

Fascinating! Thank you for the tip, Andrew!

Post Readers: It appears this project has been in the public domain for a little while. Please comment if you’ve tried implementing RedHawk in your SDR system!


Do you enjoy the SWLing Post?

Please consider supporting us via Patreon or our Coffee Fund!

Your support makes articles like this one possible. Thank you!

Spread the radio love

Finding a repair service for boat anchors and other vintage valve/tube radio gear

Vintage tube radios will likely survive an EMP, but how do you power them without mains electricity?

Here’s a common question I receive from SWLing Post readers:

“Where can I have my vintage valve/tube radio repaired? Can you recommend a good repair service?”

The answer isn’t always a simple one, especially for those living in rural or remote parts of the world.

Go local

The short answer is: try to find a local repair service.

Unlike modern solid state radios, “boat anchors” (metal chassis vintage radios) are heavy and very pricey to ship.

Some repair services and retailers won’t even consider shipping vintage metal chassis radios because of the likelihood of damage or a tube or other component loosening during transit resulting in a DOA (Dead On Arrival) situation. They insist on in-store or local pickup/delivery.

Johnson Viking Ranger transmitter

 

Last year at the Dayton Hamvention I was speaking with an acquaintance who restores and repairs vintage tube radios–he specializes in WWII and Cold War era boat anchors (Collins, Signal Corps, Hallicrafters, National HRO, etc.). Although he makes a tidy profit from doing repairs, it’s most certainly a labor of love and not the most profitable use of his time.  He told me that he recently stopped accepting any repairs other than those delivered and picked up locally.

He told me he took great care in packing equipment after repairs had been made–he’d secure all components so that they couldn’t budge during shipment and would either double box or use industrial strength cartons. Being so diligent, his return shipments almost always arrived unscathed, but customers would complain about the shipping costs. He could, of course, skimp on packaging, but then risk his repair work being undermined by rough handling. He was never willing to compromise on shipping and I certainly don’t blame him.

So again, due to the complexities of shipping heavy gear, I always recommend trying to find someone local to do your “boat anchor” repair work first.

Where can you find a local repair shop? If you belong to or know of a local ham radio club, stop by a meeting and ask around. If there’s a vintage radio repair technician in town, someone in the club can likely connect you.

Shipping boat anchors

With that said, there are some excellent repair technicians out there who will take work via parcel shipments, but be prepared to pay upwards of $50-150 each way each way (depending, of course on the radio size and weight).

Lighter tube radios are easier and cheaper to ship, but should still be packed carefully. Bakelite radios, for example, are lightweight but incredibly fragile.

In short: if you ship your vintage radio, pack meticulously and confirm that your repair person will do the same.

And where do you find repair services? I point readers to radio repair service reviews on eHam.net. You might also search the QRZ.com forums or even post a question.

Let’s be clear: some radios are worth the shipping costs!

I am fortunate in that I do have a local friend and mentor Charlie (W4MEC) who repairs tube gear. Better yet, Charlie is willing to teach me how to do repairs and alignments myself. This, I would argue, is the best of both worlds!

A Note of Caution: When it comes to repairing tube/valve gear, I believe you should always learn the ropes with an experienced technician. Unlike battery-powered solid state devices, tube gear is mostly high voltage. If you don’t know what you’re doing inside the chassis of a tube radio, you could be severely shocked or even electrocuted. No radio is worth that price.

Who do you recommend?

If you have any advice about repairing boat anchors and other vintage electronics, please comment! Also, if you can recommend a repair service, please share details.

Spread the radio love

“Crystals Go To War”: A 1943 film about the production of Signal Corps radio crystals

Many thanks to SWLing Post contributor, Charlie (W4MEC), who shares this fascinating film which documents the production and calibration of crystals in 1943. I had no idea of the amount of labor and attention to detail this process required–an absolutely fascinating process:

UPDATE (08/09/2022): the YouTube account associated with this film has been deleted by the owner.

Click here to view this same film now hosted by the Antique Wireless Association.

Spread the radio love

Terry remembers monitoring an eventful Sydney to Hobart yacht race

Many thanks to SWLing Post contributor, Terry Cominos, who shred the following story following our recent post about the Sydney to Hobart yacht race. Terry writes:

Here is my story…

It must have been 20 plus years ago whilst monitoring the Sydney to Hobart yacht race on my AOR AR3000.

Around midnight the yacht “Mem” announced a man was lost overboard. They were turning back to find him. The Captain of the oil tanker “Ampol Serel” on his way to Sydney declared he was turning back to assist in the search.

It was a long night with several yachts searching and the “Young Endeavour” providing radio relay support.

More than an hour passed before the “Ampol Serel” arrived on the scene with its powerful search light.

The search was hampered by a swell yet before first light “Ampol Serel” picked up a reflected flash off a life vest.

The sailor was eventually found by a competing yacht and taken on board where he was examined and treated for hypothermia by a doctor onboard.

Several years later I visited the Australian Maritime Museum where the life vest is on display.

That morning I learned a lot about the sea, radio and human nature…

Thank you for sharing this, Terry, and reminding us  that those of us who monitor radio sometimes have a front row seat to events as they unfold.

Source: OneTubeRadio.com

I recall this 1957 Hallicrafter ad from Boy’s Life magazine which of course implies that we may even be in a position to help.

The thought of hearing or assisting–remote as it may have been–certainly had an influence on me when I first started exploring the shortwave bands from my bedroom with a Zenith Transoceanic some forty years ago.

Thanks again for sharing, Terry.

Post readers: Have you ever been witness to events as they unfolded on the air?  Please share your story!


Do you enjoy the SWLing Post?

Please consider supporting us via Patreon or our Coffee Fund!

Your support makes articles like this one possible. Thank you!

Spread the radio love