Category Archives: Kits

National RF 75-NS-3 receiver kit

NationalRF-75-NS_2

National RF, of California, has introduced a new “semi-kit” receiver: the RF 75-NS-3. Here’s an excerpt from the product description page of the National RF website:

National RF’s 75-NS-3 receiver is a complete super-hetrodyne mini high frequency receiver, designed specifically for the short-wave listener, electronics enthusiast or radio amateur, who wants to use their hands and build a radio. The receiver is offered as a semi-kit in which the electronic assembly is loaded and functionally tested at the National RF facility. The customer must then go to the grocery store (yes…the grocery store!), procure a can of [Spam] lunch meat, eat it or give it to the dog, and then proceed to drill and paint the can, in order for it to become the receiver’s enclosure! […] Detailed drilling instructions and final assembly instructions are provided as part of the kit. All other parts required for completion of the receiver are provided as well. Recognizing that the finished assembly looked somewhat like the fabled Collins receiver of the ‘60s, the 75S-3, (particularly when the can is painted a light gray) National RF engineers dubbed it (with tongue firmly planted in cheek, of course) the 75-NS-3! Although we have had fun packaging this receiver in a lunch meat can, it is nothing to turn your nose at! Its performance and portability will surprise you, and it is an ideal radio to bring with you on any trip!

75-NS_3

The receiver architecture is that of a single conversion super-hetrodyne receiver, that is capable of receiving AM, SSB, or CW. The receiver incorporates a dual gate FET as an RF amplifier with manual peaking and gain controls. A ceramic filter is used in the IF section with a front panel switch that controls a broad or narrow IF response. Other front panel controls include audio drive, BFO setting, and a band switch for the HF bands. The 75-NS-3 has internal receive frequency coils that are switched at the front and rear panels. The frequency range of the receiver, over three band set positions, is 3.5 through 12 MHz. This allows reception of several international short-wave bands, the 80, 60, 40, and 30 meter amateur radio bands, and of course, WWV time and frequency standard stations at 5 and 10 MHz.

For those who simply want a lower cost receiver to monitor the shortwave frequencies, National RF offers two variants of the original receiver: the 75-NS-1 and the 75-NS-2. Both are based on the design and circuit of the 75-NS-3, but do not have the band switching and frequency range of the 75-NS-3 receiver. The 75-NS-1 covers between 3 and 6 MHz, including the 80 and 60 meter amateur band. The 75-NS-2 covers between 6 and 12 MHz, including the 40 and 30 meter amateur bands. Both units have the fixed ceramic resonator band width set for about 6 KHz. And, of course, they are both designed to fit in the tasty potted meat can!! All other specifications presented apply to both of these models as well.

Pricing of the 75-NS-x versions:

  • Type 75-NS-1 Mini HF Receiver Semi-kit (covers 3 to 6 MHz) $189.95
  • Type 75-NS-2 Mini HF Receiver Semi-kit (6 to 12 MHz) $189.95
  • Type 75-NS-3 Mini HF Receiver Semi-kit (band switched from 3.5 through 12 MHz in three switched positions) $269.95
  • Shipping and Handling to within the US $10.00 each

Click here to view on the National RF website.

Video: Stephen’s Poldhu Radio Kit

Radio-Kit

Many thanks to SWLing Post contributor, Stephen Cooper, who recently shared a video on the SWLing chatroom:

I’m a sucker for cute radio kits, so I purchased one of these from the UK-based seller on eBay as well. There are two kit packages: one with the receiver only, another with the receiver, amplifier and speaker. Shipping is free–even to the US–and pricing is fair (19 – 25 GBP or roughly $30-38 US)

Click here to search eBay.

Readers: if you haven’t checked out the SWLing chat room, I would encourage you to do so! There’s almost always someone there and, many evenings, readers share reception reports in real time. Click here to check out the chat room.

Neil’s updated radio kit guide

My Ozark Patrol regenerative receiver kit

My Ozark Patrol regenerative receiver kit

Neil Goldstein, W2NDG, has just informed me that he’s updated his comprehensive radio kit guide which can be found at RadioKitGuide.com. Many thanks, Neil!

The next kit I have on the table is the Sawdust Regenerative Receiver by BreadBoard Radio. Should be a lot of fun and a nice weekend project (once I have a free weekend to complete it). Still, I think I’ll check out Neil’s list to see if there are any new kits I’ve overlooked–after all, fall and winter kit-building seasons are just around the corner!

A three transistor homebrew shortwave radio

(Photo source: netZener.net)

(Photo source: Instructables)

SWLing Post contributor, Richard Langley, writes:

Came across this site on building a 3-transistor shortwave radio similar to the kit offered by Radio Shack years ago:

http://www.netzener.net/index.php/8-project-articles/5-3-transistor-short-wave-radio

It was featured on the Instructables site:

http://www.instructables.com/id/Three-Transistor-Short-Wave-Radio/

Very cool!  Thanks for sharing this, Richard.

When I have a little time, I’ll go through my parts box and see how many of these components I already have. The author also supplies an excellent assembly manual for download and print. It would be fantastic if someone would kit up the parts list and offer it as a package. Regardless, this will make for a fun winter project!

Tinkering with the Credit Card Crystal Radio

Credit-Card-Crystal-Radio-2

A few weeks ago, we published a short post about a credit card crystal radio from an eBay seller in the UK.

I purchased a kit–at $17-18 US shipped, it’s quite a modest investment for what might be a fun little project.

Credit-Card-Crystal-Radio

The crystal radio arrived while I was traveling during Easter break, but my free time has been so (extremely) limited lately, I was only able to unpack and try out this new arrival yesterday.

Credit-Card-Crystal-Radio-1

The biggest surprise for me was the fact that this isn’t really a kit–the board is fully populated and requires no soldering whatsoever. The board feels of very good quality.

All that is required is connecting the high-impedance earphone, earth/ground and aerial/antenna to the board. Since all of these components can be connected with the supplied alligator clip cables, getting it on the air took all of 20 seconds. I simply hooked up the ground and connected the aerial to my sky loop wire antenna.

I instantly heard a signal and station ID which confirmed it was our closest local broadcaster on 1010 kHz.  This station isn’t of the blowtorch variety, but is the strongest one I receive on the MW band simply due to its proximity. Audio was quite faint through the earpiece, but I believe if I tinkered with antenna length and the two variable capacitors, I could improve reception.

SWLing Post reader, Richard Langley, received his crystal radio and had a very similar experience with reception.

Credit-Card-Crystal-Radio-4

With any crystal radio (especially one this small), performance is directly correlated with antenna length, availability of a good ground connection and, of course, strong broadcasters in your vicinity.

I plan to spend an evening tinkering with this little receiver and see if I can pick up some of the night time powerhouse AM stations on the east coast.

I can say this: if you’re looking for a simple, uber-compact emergency receiver for your go-bag, bug out bag or emergency kit, this one will certainly fit the bill. This crystal receiver and all of its components weight no more than a few ounces and could easily fit in compact pouch or sleeve.

Have any other readers have enjoyed tinkering with this little emergency crystal radio?

If you would like to purchase one, try searching eBay with one of the links below. The product will only appear in the search results if currently available.

New Franzis shortwave radio kit

FranzisKitRadio

Many thanks to SWLing Post reader, Franz Miller, who writes:

“I’ve pasted a link below to the webpage at Conrad in Germany for yet another Franzis radio kit; no idea how good it is, but it looks neato-retro to me.  Covers longwave, medium, shortwave VHF, & UHF, allegedly.  Price on Conrad’s website is around 69 Euros.”

Click here to view the new Franzis Radio Kit on Conrad’s website.

I truly appreciate the reminder, too, that I have a previous model Franzis kit somewhere in storage that I need to unearth and build! I assume this new Franzis model also has a cardboard chassis.

Update–Tomas adds the following comment:

Here is a link to the Franzis site where there are several pictures and also a two minute video demonstrating the kit.

http://www.franzis.de/elektronik/lernpakete-elektronik/der-grosse-franzis-radiobaukasten#

Of course, for SW it only supports the 41-meter band.

Crystal radio credit card receiver

CrystalReceiver

On a tip from my good friend Dave Cripe (NM0S), I just purchased this cute crystal receiver kit from a UK-based seller on eBay.

The price is 8 GPB plus 3.50 GPB for shipping. After PayPal currency conversion, I paid $17.63 US shipped from the UK–a very fair price. The kit is supplied with 5 meters of antenna wire, a high impedence earphone fitted with crocodile clips, and two double crocodile clip leads. Each unit is also tested prior to shipping. The seller also has a 100% positive rating on eBay.

I’ll certainly make a post about the radio once I receive and build it. While there aren’t as many blowtorch broadcast stations to hear these days via a crystal set, with an ample length of antenna wire, you may be surprised what you will hear. Certainly a fun and lightweight item to take camping or place in your bug out bag. No batteries required!

Update: Since making this post, it appears the item number has changed since the seller had to list a new lot of kits.  Below, I’ve made two links that search eBay based on the description, not item number: