Qodosen SR-286 Digital Display Noise Quirk

[@skinnyblinddude]

Hi there Gary. As a follow-up to my previous post, I experimented and found a suitable workaround to deal with the digital display noise problem beyond just disabling the display. I gave the matter some thought and it dawned on me that the display is in mightily close proximity of the built-in antennas. So then, I played a hunch that plugging into the DX-286 with an external passive loop antenna might at least rid the radio of that very annoying effect by virtue of it being distanced away from the interfering noise source. Yep! With external antenna switched on, amp switched on and with my Radio Shack #15-1853 passive tuned loop connected via its linking cable, there is absolutely no digital hash or display-induced interference at all. Now I can leave the display activated without sacrificing reception. The bonus is that the antenna can be rotated independently from the radio. The DX-286 pairs nicely with my Radio Shack #15-1853 with astonishingly excellent sensitivity! I would imagine that shielding the digital display from the built-in antennas is no small technological feat! Why the issue varies in severity from unit to unit is perplexing, but I have a good feeling that the problem will be rectified in future production.

[@DXerGary]

Hi Skinnyblinddude, Thanks for your investigation! This noise quirk is somewhat irritating in both the SR-286 and DX-286 models, depending on how noisy a display you get. The quality control in the display factory is very uneven.

[@skinnyblinddude]

My DX-286 exhibits this digital hash as well. It’s audible on other frequencies too throughout the MW band. Disabling the display by simultaneously pressing 1 and 3 entirely eliminates the digital hash. It’s a quality control issue, but what do you expect from an $80 radio. If Qodosen can correct this issue, that would be a good thing.

I hear that hash noise. Hash noise can ruin an otherwise nice radio. I do own the SR-286 and while it's not perfect I do think it's technically the best radio I own AND it makes fun to use. The hash noise I hear on your videos is Very mild though. By any chance did the audio compression either by your camera or YT encoding reduced that noise? I had that in the past that recordings of such Kind get affected by digital compression.

[@DXerGary]

Hello Johann, actually I first discovered this display hash noise on some SR-286 models when neither the camera nor a YT recording was involved. I agree with you that the hash noise in the video is pretty mild, but since these loopstick transplant modifications are designed to encourage very weak signal AM-DXing, anything that interferes with that goal should be investigated before the radio is modified. Overall, though, I do agree with you that the SR-286 is a very fun radio to use, and that the TEF-6686 chip provides a real technical breakthrough! 73, Gary

[@richardmerriam7044]

Outside (MW band) with the whip and amp on I noticed a rhythmic ticking sound. I pressed the #1 and #3 buttons to blank out the LCD display. The ticking sound stopped.

[@user-bk7od1bh4z]

عمل جدا رائع لكن يبقى الراديو الياباني هو الافضل .. للأسف اليابان لم تعد تصنع كالسابق...😢

[@AlexeyDXman]

Did you try to switch off display by pushing knobs 1 and 3 together? How much difference?

[@IberiaDX]

Hi! When display is disconnected, noise disappears. But this is not a good solution as the units would not radiate any hash or they had to be well screened, at least!

[@DXerGary]

Yes Alexey, like Jorge (IberiaDX) says, the SR-286 display noise does go away when you press the 1 and 3 buttons simultaneously. But of course the lack of a display isn't very convenient for DXing, especially when you are trying to change frequencies and investigate multiple DX stations. Turning off the display (and the display noise) would be OK for an audio recording of one DX station, however.

[@Classic_Electrics]

Great video. It seems many cheaper AM receivers suffer from this problem. My Kaito KA600, Midland ER210, WR300 version 8, and WR400, La Crosse S83301, and Eton FR370 all seem to get it, although I have no idea how to fix it on any of those models.

[@KGJones-ok1os]

Gary, do you plan to modify the dipole antenna? I believe it is "to short", and would benefit from a longer dipole -(30+)- inches. It would be cool if these came with a modified version with a female SMA antenna connection. I know you "could" plug in a 3/8" connection to SMA, but if it gets bumped, it could break the soldier connection on the board (weak point). I'd be interested to see if its possible to modify the dipole, either to a longer antenna or converting it to a SMA female connection.

[@digitalmediafan]

I checked mine and nothing at all. Is it not locally generated perhaps ?

[@DXerGary]

No, because when the buttons 1+3 are pressed to turn off the display, the noise disappears as well (to confirm that it is display noise). You may have been lucky enough to get a model without this quirk.

[@digitalmediafan]

@@DXerGary let’s hope the new official version the DX 286 has no such issues. Much cheaper also !

[@radellaf]

If you press 1+3 to turn off the display, does that help? My DX version has a tiny bit of hash, not enough to bother me.

[@DXerGary]

Yes, turning off the display does turn off the noise as well, in confirmation that this is digital display noise. But of course, it is inconvenient to chase DX without a display.

[@radellaf]

@@DXerGary Yeah, true, lol. What bit of hash I hear does not seem to get better if I turn off the display. Must be from the CPU itself or something.

[@DLH65]

When listening to MW through headphones, I hear a regular "pop" noise, around one per second. Ever run into that issue?

[@anulearntech]

I found something similar on every radio, turned out my phone's NFC works somewhere around 11 mhz and that was sending out periodic signals to detect nearby devices which was caught on my radio.

[@DLH65]

@@anulearntech interesting, this however is specific to the qodosen. I'm going to try turning off the display.

[@anulearntech]

@@DLH65 maybe it's detecting something others aren't. Do you get it everywhere? In High rfi area and other places?

[@DLH65]

All times and locations, MW band only.

[@DLH65]

Yup, turning the display off makes the popping go away!