Many thanks to SWLing Post contributor, Steffen Schultz, who writes:
Hello Thomas,
As a regular reader of your blog, I was fascinated by the reports on the XHDATA D-220 [affiliate link] and ordered a black one. I was not disappointed. Of course it’s not a DXing machine, but finally we have a device wich reaches the reception quality of the old pocket radios again I used to carry around in my childhood. I still have a Philips D1220 from the 80s, which is even less sensitive than the XHDATA D-220.
This reminded me of my early radio days, when I would try to use the simplest methods to manipulate analog radios to do things that were not intended by the manufacturer. For example, by moving the band selector switch to an intermediate position, it was possible to get some radios to receive frequencies outside the intended range. Of course, I couldn’t resist and experimented with the D-220. It takes a bit of patience and sensitivity, but the radio really does hold some secrets.
Medium wave reception with the telescopic antenna
When I was listening to a weak station on medium wave and slowly moved the switch to short wave, the medium wave station got louder for a moment before the slide switch clicked into the correct position. In fact, the radio seems to switch to the telescopic antenna when you move the band selector a little toward short wave. A finger test on the antenna confirmed my suspicion. I also tried connecting a long wire, but that was counterproductive with all the men-made noise inside my house. Extended shortwave reception
A similar trick can be used to change the shortwave frequencies. If you slightly move the band selector from the shortwave position towards medium wave, the receiver switches to a different shortwave frequency range, covering between about 3000 and 7000 kHz. Now I was able to receive shortwave radio from Germany on 3975 kHz without any problems, and of course South Korea via England on 3955 kHz was no problem either.
I have not yet found out if the two FM bands can also be manipulated in this way, an intermediate position of the band selector seems to have no effect here. Perhaps one of the readers has discovered something?
73 and best regards
Steffen
Wittstock/Germany
Thank you for sharing these D-220 tips/hacks, Steffen!
Get a 220 for free if you buy an 808. Plus there is a $5 off coupon you can clip.
https://xhdata.com.cn/products/xhdata-sihuadon-d-808?variant=50150447907134
I just ordered one. I think this may expire today 30AU24.
-Bob W8RMV
These are fun tips – many Thanks! I’m reminded that when I was a kid I discovered that with one ferrite antenna coil lead disconnected, an AM transistor radio would receive a limited shortwave range. I had immense fun with this “mod”!
What is the best SW radio for reception only (USA)?
I do not live in the USA to buy your version of this radio. Thank you to KW for the links.
I got some right and some wrong . It does use a tuning potentiometer fed into pins Tune 1 and Tune 2.
This chip definitely is a Digital Signal Processing. This is characterised by the pair of analog to digital converters etc. There is a voltage sensitive band pin on the dip used to select one of the many bands. As a result there is a pair of bands, one for the Americas and the other for elsewhere. Similarly in the FM band but the 87 -108 MHz uses 75 µs de-emphasis used in the Americas and the other band 64 – 108 MHz for the 50 µs de-emphasis used in the rest of the world. The wrong de-emphasis selection will either boost or reduce the high pitched sound volume which also includes the hiss in weak signals.
On all the photos in these posts only contained a band selection switch of 3 positions. There is no second slide switch. As a result they must sell an American version for that market and another for elsewhere.
The radio uses an Si4825 IC on a single sided PCB. It’s a mono-FM chip with voltage (single pot) tuning and voltage select-able bands, look for application note AN738 on the Skyworks site for details on this. The radio pretty much uses the sample circuit shown.
The 4P4T switch that is used to: (1) change the tap point in a resistor chain to determine the band, (2) change the antenna input from the rod to the loop, (3) turn off the antenna amplifier. The 4th pole is open to use as needed.
There are many possible ways to reconfigure the radio with very little work, for example:
Because I didn’t need the FM2 band I modified the band switch to remove that and add a second SW band covering 3.2 – 7.6 MHz in it’s place. You’ll need to cut a couple of traces around the 4P4T switch and three jumpers. There are many possible SW bands that you could set but you’ll need to modify the voltage divider chain. Also, there are many narrow (fine really) resolution bands that can be set by lifting pin 1 on the Si4825 so that it is not pulled to ground. If you just do that on an otherwise unmodified radio the SW band will cover just 5.95 to 6.2MHz, for example.
Very interesting, thanks! I was wondering what would be inside those despite the “9 transistors and a handful of coils” optics. That sounds like they lend themselves to some happy circuit-bending afternoons! 🙂
Ever since I found a keypress mod for my old (now basically failed) Sony Wavehawk scanner than enabled shortwave reception on it, I’ve liked the idea of modifying what a radio can do without getting inside it and altering the electronics. I haven’t tried the MW trick yet, but the SW trick does seem to work. I tuned in a station down near the 5.6 MHz mark that was coming in OK, then slowly moved the band switch towards MW. When the station disappeared, I assumed the shift happened, so I stopped and tuned up the dial to around where I thought it should be if it was now in the ~3 to ~7 MHz range as the post says and was able to find the same station again. Checking with another radio to confirm the station I was hearing, it was 6030 kHz and I was getting it at around 16000 kHz on the dial, so something must have shifted. Thanks for these tips! It’s always good to know about stuff like this.
Yikes, I’d better check my Sony Wavehawk scanner to see if it’s still functional. The button-press shortwave mod was fun to do and it has made the radio twice as fun.
I just tested the MW-on-the-whip trick on my green D-220. I tuned in a fairly weak station to the west and confirmed that I could null it out by rotating the receiver. Then I carefully (and I do mean c*a*r*e*f*u*l*l*y) moved the band switch until I heard an increase in signal strength. I rotated the receiver and observed NO NULL in any direction. Oh, this is interesting!!!
Being daytime I haven’t tried the other trick yet. Maybe tonight I’ll see if I can catch CHU on 3330 or hear some 75 meter ham SSB.
Thanks Steffen and thanks Thomas for posting. Back in the late ’50s and early ’60’s, transistor radios were very popular, especially the small portable ones similar to those in the photo. They were AM only. It’s nice to see these once again with additional bands.
Technologically speaking, it’s a great time to be living.
That shortwave switch trick is awesome – will definitely try that!! I just posted a YouTube short on the D-220 performance in a radio quiet zone (just unboxed 2 days ago). With only the small whip the shortwave DX performance is really quite good for this inexpensive radio!
10pm CDT in N Minnesota – 5.6 to 12 mhz
https://youtube.com/shorts/XQOJS7d8Anc
Steffen,
Waaay cool!
Cheers, Jock
Very interesting – looking forward to trying that out! Thanks for the tips!