Re: More Chinese AM radio kits
At last! some luck with this S66D. I believe that it is very much like the HX-6B, except there is provision for an earphone jack (which I have not fitted).
I peaked the white & black cores with an injector at around 460 Khz, observing the amplitude of the waveform arriving on the base of VT3. I had to take the volume control off
You see that there is that mark by R4. Long ago someone who could read Chinese said that it referred to adjustment of the value, but on what conditions? Can't remember.
As you can see R4 is listed as 30K, I fitted 51K.
The best improvement I observed was after throwing the supplied speaker in the bin & fitting an 8 ohm 0.2W 50mm plastic cone speaker that is 11mm deep. It is the sort of component that you'd fit in a shower radio.
I do have an old Japanese pocket radio speaker, but i'd have to molest the back of the case to accommodate the magnet bell.
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