TECSUN S-8800 - THE BIRDIE PROBLEM

TECSUN S-8800 - THE BIRDIE PROBLEM

Recently, Tecsun announced and released onto the market the new S-8800 receiver. Thomas Witherspoon K4SWL at the SWLing Post has indicated that sensitivity, selectivity and audio fidelity are very good for this new unit.

BUT.....in a post on February 12, 2017, entitled Tecsun S-8800 update, Thomas discovered that his new S-8800 has a serious fault, which could potentially drive radio enthusiasts mad! In tuning around the dial, he found the radio has many "birdies". In the same post, he notes that Bertrand Stehle F6GYY also found birdies on 4 spots in the mediumwave band and 63 frequencies across the entire shortwave spectrum. Not good!

In reading the comments that followed Thomas' post, I noted that a few writers seemed a little confused about what a birdie is and how it differs from radio frequency interference. Hopefully, the following explanation will shed some light.

The term "birdie" is, I guess, derived from the type of sounds that are emitted from a receiver having this problem. It can take on a variety of forms,  like a squealing or whistling sound, or perhaps a warbling sound, or a hash noise, or indeed, even a silent carrier. In a particular radio, a birdie could appear on one or many frequencies across longwave, shortwave, mediumwave or into the VHF spectrum. And it will usually be permanently there on the same frequencies every time. 

Occasionally, you will find birdies smack bang on frequencies that you might want to listen to. But, unfortunately you can't really do anything to get rid of these nuisances because the design faults are in the the receiver itself. You can test to see if what you are listening to is a birdie by simply disconnecting the antenna. If the squealing/whistling/warbling/hash/silent carrier is still there without any antenna, then it's a birdie - an internally generated carrier by the receiver's own circuitry.


Often, these carriers are generated because of insufficient grounding of some components in the circuit, or improper shielding around certain elements of the circuit. Occasionally, toroids introduced into the circuit may help reduce the severity of the birdie. But generally for the average radio listener, there's not much you can do if you discover your radio is plagued with internally generated spurious signals and harmonics.

However, there is a difference between a birdie and an externally generated radio frequency interference signal. For example, in my radio shack I have a wireless modem range extender that creates all sorts of whistling RF interference when tuning my receivers above 15 mHz. These spurious carriers affect all four radios in the shack! So, therefore it can't be called a birdie, as all the radios are picking up the signals - that's just a straight RFI problem. It can be tamed somewhat by using those ferrite clip-on RFI filters. But sometimes the signal out of the modem can be so strong that it can be even heard without the antennas connected to the nearby radios.

In this highly electronic environment in which we live, stray radio frequency interference is seemingly everywhere. Knowing the difference between birdies due to design or manufacturing faults in receivers and stray RF interference getting into your receiver can be tricky to identify. When checking to see if your radio is subject to birdies, make sure you are testing in an environment where there is no RFI. Turn off any RFI producing appliances before making observations relating to your receiver.

So....it would seem that, in its current circuit design as reported by Thomas in the SWLing Blog, the Tecsun S-8800 is generating these noises itself. Could it be that Thomas just scored a bad (faulty) unit? Quite possibly! Perhaps quality control on this new model is just not up to speed yet. Although I have my doubts......

How to fix it? Well, hopefully Tecsun can 1) check that circuit grounding is adequate and effective, 2) use an appropriate level of shielding within the circuit, or 3) make some alterations to the existing circuit design in order to overcome this dilemma. This may not be easy to achieve, especially if there are hundreds of units already rolling off the assembly line. One can only hope that later generations of S-8800s will see the problem remedied.

It's a pity, because the S-8800 looks to be very promising receiver with many interesting features. If you haven't read Thomas' excellent article yet, here's the link once again. Hopefully, he will have better news in the not-too-distant future.

73 and good DX to you all,

Rob Wagner VK3BVW

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