On 06/14/2013 09:30 PM, Guerner Remi wrote:
>
> Hi All,
> I have purchased a 12V battery charger for my iPad. This morning I flight
> tested
it for the first time and was disappointed by the results:
> 1. The charger makes noise in the radio.
Basically this reveals that the charger is a piece of junk. Apparently
it was deemed too costly for the manufacturer to use some proper
shielding and filtering.
It may help to establish how the noise gets into the radio. What happens
if you disconnect the antenna plug? If the noise persists, the
interference enters the radio via the power supply or via direct
radiation into the radio. (The latter can be established by moving the
box closer or further away from the radio and see if it makes a
difference). If the noise disappears when you disconnect the antenna it
proves that the noise enters via the antenna (or antenna wire).
You can try to fix it yourself. Some things you can try:
1) Solder some capacitors directly between both input wires and both
output wires, as close to the box as possible. (I would open up the box
and solder the capacitors directly over the internal terminals).
Something about 6n8 (6.8 nanofarad) would be about right, it is not that
important.
2) Trim the in- and output wires as short as possible. (This is most
helpful if the noise enters the radio via the antenna).
3) If the device has a plastic housing, put it in a metal box. (This is
most helpful if the noise enters the radio via the antenna or by direct
radiation).
4) You can also wrap the input and output wires through a torroid,
similar to that as used for the VHF-antenna.
If these simple fixes don't give any improvement I would throw the box
away (or use it in the car or other place where it doesn't matter).
Frans
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