If you spent the 1970s obsessively browsing through the Radio Shack catalog, you probably remember the DX-160 shortwave receiver. You might have even had one. The radio looked suspiciously like the less expensive Eico of the same era, but it had that amazing-looking bandspread dial, instead of the Eico’s uncalibrated single turn knob number 1 to 10. Finding an exact frequency was an artful process of using both knobs, but [Frank] decided to refit his with a digital frequency display.
Even if you don’t have a DX-160, the techniques [Frank] uses are pretty applicable to old receivers like this. In this case, the radio is a single conversion superhet with a variable frequency oscillator (VFO), so you need only read that frequency and then add or subtract the IF before display. If you can find a place to tap the VFO without perturbing it too much, you should be able to pull the same stunt.
In this receiver’s heyday, this would have been a formidable project. Today, a cheap digital display will do fine. As it turns out, this radio has some bands that tune to the VFO’s frequency minus 455 kHz and some bands tune to the VFO frequency plus 455 kHz. With a microcontroller you could deal with this easily, but [Frank’s] solution was to simply use two displays. They are cheap, so why not? The displays are configurable, so you could probably work out a way to use one even if you had to manually throw a switch to do it.
The displays draw power from the radio’s lamp sockets. The real trick to the project is finding a place to tap the VFO frequency and then doing so in a way that doesn’t kill the oscillator or introduce instability. [Frank’s] design uses a capacitor to couple the oscillator’s energy into the counters.
If you don’t want to use an off-the-shelf display, it is pretty easy to count frequency with most microcontrollers. Some have dedicated hardware for this purpose. A common trick is to count the number of zero crossings over a period of time and scale to how many you would have in a second. There, are, however, a variety of methods.
We have to admit that while we enjoy old radios, we also enjoy a digital display. Of course, another answer would be to replace the VFO completely, but that would negate the cool old dial.
I still have the DX-160 that I bought in the 70s as a teenager, using the proceeds from cutting lawns on summer.
I always wanted to get into it as a kid, but lacked the resources. What are some cool or interesting things to check out with shortwave these days?
There are online SW receivers that you can control yourself through a web interface all around the world these days, check out kiwiSDR
I had the DX-150B as the receiver for my Novice station.
I had the DX-160 and years later, an SX-190 which was the last great unsynthesized SW radio. I don’t know what happened to either of them, probably traded for some other stuff, but I bought another SX-190 about 20 years ago and still have it.
When I got my first furnished bachelor apartment all I had was a sleeper sofa, a kitchen bar, two bar stools, and my DX-160. When I would bring girls over, they would see the radio and ditch me. Sigh…
good riddance!
a couple of girls I took home saw my DX160, turned it on and we listened to “The Hobbit” on BBC world service
it became a regular Tuesday night “thing” for us
Love me, love my receiver.
Old 70’s/80’s stuff plus being stuck at home has had it’s effect. In the voice of Madonna: Let’s get Digital, Digital!!, I wanna get Digital!!! Let’s get into Digital!! I wanna see those LEDs, NOT LCDs gotta see those LED’s…(or Nixie tube would be OK :-) )
lol; or Olivia Newton-John
I knew it was Olivia Newton-John too, I was just to embarrassed to say it.
“If not for you!”
lol; you guys are killing me
https://www.youtube.com/watch?v=yyouhbgAiCA
Physical by Olivia Newton-John was by some counts the best selling single* of the 1980s spurred largely by the aerobics craze in the U.S.
*I think Thriller was the best selling album of the ’80s.
I had a DX 160 back in the day. I used it to listen to an air Force radio show called radio man’s radio program back in the day. All these years later I was surprised to find the same radio program by the same disc jockey online.
Sounds cool! Got a link? My search has turned up nothing of use…
Hmm, that was supposed to be a reply to Tom P regarding the Air Force radio show… if only I could edit my comments
I did this very type of conversion to my DX-160. I added a single FET buffer to the IF section, routed to a BNC connector on the back. The IF stayed nice and steady when adding/removing the display. I only used a single display though, as mine would let me adjust the offset +/- with just a button press.
There are little frequency add-on displays sold as modules or soldering kits on places like eBay and Amazon that are marketed for use with ham transceivers. They are pretty cheap, easily under $20US. They usually have two programmable offsets and will switch between them by setting some pin high or low. It’s how they handle receive vs transmit but could probably be used for band-switching in this project. Many of them are small enough it might even be possible to cram it behind the glass of the radio’s own display assuming the goal isn’t an easily fully reversible mod. Perhaps it could go under the S-meter where the logo is.
Huh, I actually picked up a DX-160 a few years back — it works fine, but the tuning is a bit off on a couple of bands (as shown by where I could find WWV). I meant to go through the calibration routine, but ran into a technical snag — my function generator (an old Wavetek 115) tops out at 1MHz, and the old HP RF generator my makerspace has doesn’t start until 50 MHz. This could be great as an end-run around that.
This is a blast from the past — I had a DX160 growing up, and in the February 1977 Popular Electronics there was an article titled “Digital Frequency Readout for Shortwave Receivers” that was exactly this hack. Page 47 in this pdf: https://www.americanradiohistory.com/Archive-Poptronics/70s/1977/Poptronics-1977-02.pdf I never got around to building it but I remember studying the schematics and article closely.
I ordered that kit and built it, and it changed my shortwave listening forever. Never again did I have to guess if I was on the right frequency. I eventually replaced my DX-160 with an AR88-LF, and the digital frequency display worked perfectly with it too!
Thou shalt not hacketh the front panel!
My uncle gave me a DX160 and like a fool I never really used it other than to listen to coordinated universal time. It ended up probably in the garbage. I kicked myself now for being so stupid and not getting into it. I just got my technicians license at 56 and would give my left arm to get that radio back just to play with.
I’ve had mine for 30+ years. Was just getting a new antenna setup for it