Hi.
A new 7 shortwave + AM + FM receiver has 2Hz noise bursts at maaany locations in the tuning dials, mostly at shortwave. It works, receives deficiently.

It is a very cheap receiver, based on a single tiny complex IC
Page 26 has a generic schematic. Not much to see. Its actual printed circuit board is mostly empty.
----> http://aitendo3.sakura.ne.jp/aitend...radio/KT0913/KT0913_datasheet_V12_aitendo.pdf

If anyone can suggest actions where to troubleshoot the problem, it will be nice to learn and have it working in decent shape, perhaps it is worth the effort... Paid $7 new in sealed box

Edited- added interesting link---->

 

It has almost unbelievable spec's. It is too bad the Chinese manufacturer cannot make good reliability.
EDIT: The IC might be Japanese.

 

Have you tried it in several locations? Locations meaning a few miles apart or kilometers apart. I guess the first step is figuring out if the noise is generated internally or from an external source.

Ron

 

What's receiving the shortwave signals?

 

Shortwave bands have a lot of noisy spots. Not a lot that you can do about it. Are the 'bursts actually 2 Hz? How did you measure the frequency. T

There are a lot of frequencies that have a buzzing sound -- at least there used to be - caused by high speed radio teletype.

If you got something that well packaged for $7 you're lucky if it works remotely well.

hj

.

 

The YouTube video is in Japanese, ... Ah So!!

 

My guess would be a stray I2C command doing something unintentionally (e.g they meant to toggle the clock colon at 2Hz but accidentally toggling gain).

Or, the soft mute feature may be cycling 3.7.2 in datasheet.
If signal is falling below threshold, the Unit will slowly go to mute. If batteries are weak, the speaker load may cause low amplification and unit will slowly mute itself. Then, once muster, battery voltage recovers and unit unmutes (repeat).