This is a short video that shows my external Arduino-controlled frequency synthesizer that is used to make the JRC JSB-20 frequency agile. Tuning is implemented by means of up/down switches much like the decade switches used on many military packset radios, although knob-tuning can be done just as easily. I have not yet printed a graphic overlay so the bare capacitive touchswitches are still visible, but any desired graphics can be added to customize the keypad. As the photos show, the LCD display is backlit for easy viewing.
The radio can be configured for four channels between 3 and 9 MHz, but with the synthesizer substituting for crystals, I just aligned the first three channels for the middle of the 80, 60, and 40 meter bands. Thus the channel switch now works like a bandswitch, and tuning within each band is done from the keypad.
JRC sold this as a USB-only radio since outside the ham world, all mil and commericial SSB users operated on USB only regardless of frequency. However the synthesizer make it possible to have selectable USB/LSB which is obviously a requirement for normal ham use. However I do use USB on nets like the MMRCG Saturday morning net on 7296 which is conducted in USB mode because of this restriction in some mil/commercial radios.
The internal construction quality is very high as can be seen, yet the two main boards and front panel can be separated easily for repairs or re-crystalling. An innovative feature is the use of varactor tuning diodes for each tuned circuit so alignment is accomplished by adjusting a single trimpot that applies the needed voltage to peak the signal for each frequency. These tuned circuits are broad enough that it's possible to QSY within a band but also makes the JSB-20 receiver more susceptible to overload and intermod when many strong signals are present. I've found this to be an issue on 40 meters at night when the 41 meter SWBC stations are blasting in, but it would be much less of a problem using a whip or less efficient antenna in the original application. Waiting for different propagation or trying an alternate frequency would have been the protocol in the field.
Alan Barrow KM4BA has been responsible for creating the JSB-20 group and for making the complete package of technical information possible, without which I would not have been able to do the modifications and enjoy using my JSB-20, so a big thank you, Alan!
73, Bob W9RAN
![]() |
Go Mobile! That was an attractive marketing message to 1960s era hams who were enjoying the fun of operating SSB mobile, and WRL knew a low-cost rig that didn't have to be hauled back and forth to the car would be a winner. Heathkit and Swan had already proven that with their single (mono) bander transceivers, but what if you're heading out in the middle of th... READ MORE
- Robert Nickels (ranickels), 03/27/2021
|
![]() |
After the conclusion of World War II, there were only about 300 radio amateurs in Japan. In the year 1952, the JARL reported that only 30 provisional licenses were granted. Realizing the value of ham radio in developing a technological workforce, Japan introduced its entry level Class 4 licence in 1959 - it would prove to be the world's most succ... READ MORE
- Robert Nickels (ranickels), 03/24/2021
|
![]() |
Every radio aficionado can recognize at least three notes of music: G-E-C - the famous NBC chimes!In fact there is so much history about the chimes it deserves it's own website, and someone has put a great deal of effort into creating one: The NBC Chimes Museum A Celebration Of Old–Time Radio’s Most Famous SignatureCLICK HERE TO VISIT THE NBC CHIMES MUSEUMIt is wel... READ MORE
- Robert Nickels (ranickels), 03/20/2021
|
![]() |
The Codar AT-5A long-sought addition, enabling my mid-60s UK ham stationCategory: Vintage Ham Radio
- Robert Nickels (ranickels), 03/20/2021
|
![]() |
How many got their start in radio with a Christmas gift? And how many times did it come from the Sears or Mongomery Ward "Christmas Wishbook"?Mine did...the little crystal radio in the upper right? Didn't work very well but was really cool! The Remco Crystal radio was memorialized in this photo from about 1958 - age 7: T... READ MORE
- Robert Nickels (ranickels), 03/06/2021
|
![]() |
The B&W 850 is a kilowatt-rated tank assembly that was used in the company's linear amplifiers and sold as a component for many years. Unfortunately most of the plastics available were not capable of surviving for 50-70 years and thus have deteriorated to the point they no longer support the coil turns properly and must be repaired. Here's a typical example from... READ MORE
- Robert Nickels (ranickels), 02/28/2021
|
![]() |
Lakeshore Industries and the PhasemastersSSB pioneer company from Manitowoc, WICategory: Vintage Ham Radio
- Robert Nickels (ranickels), 02/26/2021
|
![]() |
International Crystal and the crystal synthesizerHow a crystal company reduced the number of crystals neededCategory: Vintage Radio
- Robert Nickels (ranickels), 02/19/2021
|
![]() |
Hams, especially those who enjoy operating AM and QRP should be aware of the pioneering efforts of the US Forest Service to adopt and advance the radio art in the early decades of the 20th century.The history of radio in the USFS literally takes a book to cover, but an interesting example can be found in station KBCX, the Region 1 Radio Operations Center in Missoula Montana. It w... READ MORE
- Robert Nickels (ranickels), 02/11/2021
|
![]() |
The R-1451 HF Manual Receiver aka WLR-6 "Water Boy" SystemESM-ELINT receiver from the 1960sCategory: Vintage Radio
- Robert Nickels (ranickels), 02/09/2021
|