Portable radios
Radio Components
There are three types of waves in radios:
RF: Radio frequency
IF: Intermediate frequency
AF: Audio frequency
The required length of the aerial is longer for AM radio approximately 50 meters, for FM usually 2 meters, and DAB radios usually need a 4 meters long antenna.
DAB Radios
Alvin explained that for some DAB (Digital Audio Broadcasting) radios, the design of the chips was not well thought, using a high currant rate causing power problems and that could lead to some faulty behaviour.
We had a real life demonstration of it with Tom's radio, a DAB and FM radio that worked just fine for the FM side, but the DAB was working correctly at the beginning when cold, but had some hard time as the components were getting hot.. It turned out that the reason for the dysfunction was a power supply that was not right and slightly above the voltage nee#ded for the DAB components to work well.
FM Radios
Another Radio that was brought at the skill share was an FM radio with a broken antenna. The antenna could not be fixed as we had no material to do so, but we had a good explanation from Alvin on the correlation between the length of the wave (with are very long for FM radio) and the length of the antenna. The antenna has to be long enough to resonate with the radio waves we are trying to capture.
Another radio we had at the skill share was a Goodmans "cube style" alarm clock radio cassette player.
Reported Conditions: Volume Control was definitely "problematic", the cassette player was also reported as not working.
Action: removed knobs (it revealed to be relatively easy, no tools were needed) and then one of the sides, main PCB was a little tricky to remove Removing another switch from the outside of the case, which could have been the cause of the problem and would have needed cleaning or potentially soldering / replacing, it turns out to not be faulty. Carrying on the inspection of the circuit board (PCB) there was capacitor leg touching one of the contacts of the potentiometer (volume control). Poking it away, seemed to do the trick.