Thursday, November 5, 2020

Chibo c300 world band radio

This radio has been bought ca 2000? and here i re-write slighly just for reference in this site


Possibly  the most expensive model  of the series costing € 60  contrary to its cassette size dimensions (7 x 11x2.5) .
Included with it are :

  Very small  metallic  colored buttons ( just  only thin fingers should use it!)
Real PLL synthesis . Step/Scan up and down and 30 memories . 5 kHz steps are used in SW  0.1 MHz in FM band
2 timers , including  alarm sleep function ( steps of 10 minutes with max 90 mins )
Light function  lighting for 15 secs as standard
Lock key locks all buttons on the front panel
Hi  - low tone  switch on the left
-  Case showing ‘world receiver’ and headphones ( earbuds) -  Antenna  wire
-  Handling bracket built in

-  Instruction for use in ‘Chinglish’   IN the report there was comparison with other chibo radios , that showed on ne of them was actually showing the exact frequency even it it uses a quasi digital system  . IN contrast to this , as the radio is fully digital with PLL it shown the exact freq :
FM :   87,5 -108   ≤20 µV  ,   100 kHz steps and stereo  when  using headphones
MW:   521-1620
SW:   5950-15600   continuous in 5 KHz  steps - 

A button is provided for  selection between these SW band starting points : 7.1-  9.5 - 11.65 – 13.6 – 15.1 MHz
-  Another button is provided for changing between these three bands in carousel ( MW, SW and FM) This  radio has been checked for long  time with the  SONY ICF7600 D as reference and shown contradictory   results ( as in some cases the  Sony model outperformed the Kchibo  and on other cases Kchibo outperformed Sony). Results from my measurements

Very long time for  changing  between freqs : 1.1 sec. Step button  operates also as scanning function
-  Using most by thumb of the buttons produces high local oscillator noise coming into radio -  Frequency indications  are now exact.
-  And relatively good AGC operation.( he only with some AGC??)  IN case of cross-interferenced signals however there is a very high ripple -  Headphone cable affects as antenna
-  FM sensitivity  higher regarding to 979 without the mess of overloading.
-  FM Selectivity Better than 979 but not as of 7100 . Relatively better than Sony  
-FM stereo  audio ( via ear buds)  is very good . Level as  of a medium class stereo system   SW/AM Sensitivity: Better  than 979 . Nearly same with R75 with telescopic antenna unfolded and full preamplification( 20 db) . And relatively same level with ICF 7600 D though in some cases 7600 was  better Also  it is found that  using wires more than 3 m overload  the radio.

Earbuds: Seem typical quality  stereo earbuds. About -2db  than my Philips  open ear buds with ?  atter audio response

-  AM/SW selectivity: About 6-7 kHz  . Much better than the 979  ( abt 15kHz ??) but less than 7600D (  it seems les than 4.7 kHz) . More on this in the pictures  on the end . However  as in result it produces  pleasant audio . ON parallel  listening  with Sony model  earbud to earbud for a given  freq. range audio was in the middle .
-  3 VDC  : Unkown problem with 3VDC  from non stabilized adaptor  showed locked all radio operations .
Listening with its own speaker: I found that in vacant freqs   the inner oscillator circuit is heard. NOw i never use its spaker , as i only use the Koss UR60  headphones for the best audio. Opening the cover :  All ICs have their IDs clear and are posibly  replaceable after a very lengthy  usage: 1 . Suddenly , the antenna   has been cut in half. This made  the radio possibly lose much of its sensitivity (?)on FM   but the SW  eficiency   is still very good : Using more than 3 m of wire it overloads itself 2. The  audio in FM is still very good. It has nearly the audio  of a HIfi  system , with  comaprison  with te same headphones (UR60 Koss ) 3. AM efficiency is also  quite good . Did not tested  with other comaprison but also soem low power signals are  audible And here are  several pictures of the radio:  ON the right corner clockwise : Operation LED , operation button , band button , up down freqs with cyclical buttons , mem up and down. (10 per band) Memory store , shortwave band ,sleep time (with 10 minutes steps downwards ) and background light  




A close up of the radios' botons and indicatins

Now to clsie this article that the radio after , has been defect since 2010 with no ability to repair them> There are no specific repairmen to do that 





No comments:

Post a Comment

Top posts