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Old 30th Dec 2016, 10:38 am   #1
Neil Purling
Nonode
 
Join Date: Jul 2005
Location: Hull, East Yorkshire, UK.
Posts: 2,083
Default Two or three IF stage Chinese radio kits.

I have made several of the Chinese radio kits:
There may be two or three IF stages after the mixer. Most kits have just the two stages as in the S66-E in the photograph. What advantage is there in having the extra stage?

The S66-E sounds pretty bad even after I fitted a Japanese speaker from a broken pocket radio. To do that I had to hack a hole in the back of the case to accommodate the speaker bell.
I have another radio kit that is a TRF, with a TA7642 and a 3 transistor transformer-less audio section. It does not sound so 'tinny'.

I appreciate with the narrow plastic cases and low-profile speaker these radios will not have much bass. The sound of the S66-E makes me wonder if the audio stage is incorrectly biased, or if I did the wrong thing in peaking the IF stages with a signal generator.

I can post the circuit if you wish to offer advice on improvement of the audio..
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