Many thanks for your much appreciated advice Jan.
I'm away from home now so can't do any more testing at the moment. Also, I'm
thinking I will just leave the problem in the 'too hard' basket for a while
and move on with more important things. The strobe is not critical for flig
ht so is not a high priority at the moment.
When the time comes, I'll refer again to your suggestions.
Thanks again and all the best for the festive season.
Kingsley
Sent from my iPhone
> On 24 Dec 2015, at 7:21 PM, Jan de Jong <jan_de_jong@casema.nl> wrote:
>
> Kingsley,
>
> Where I lost you:
> People like to have 5V USB charging points for their ipads etc. fed from a
12V cigar lighter socket. These are very cheap and very noisy switchers; in
terfere badly with AM radio like our COM. Mitigation involves a filter on th
eir 12V input and on their 5V output. Even so a cheap switcher radiates and d
egrades radio reception.
>
> If what we hear is the charging of the capacitor the source should be the i
nput power lines or the (transformer in) the box, not the output wiring to t
he strobe.
> With the box located at the bagage bay station it would then seem strange t
hat the antenna in the tail would be affected and an antenna near the panel (
although lower quality) not at all.
> Maybe some more experimentation with antennas would be useful: 1. moving a
test antenna from panel to tail via the bagage bay 2. replacing the tail di
pole with a 50 ohm dummy load.
>
> Jan
>
>> On 12/23/2015 11:24 PM, Kingsley Hurst wrote:
>> RON =93 I do have twisted pair power supply lines to the strobe pow
er supply thanks.
>>
>> PETE =93 Thanks for that tip . . . . . LED Strobe will be consider
ed if all else fails.
>>
>> JAN =93 Comments / answers embedded below . . . .
>>
>> Thank you all
>>
>> Kingsley
>>
>>
>>
>> From: Jan de Jong
>> Sent: Wednesday, December 23, 2015 7:36 PM
>> To: europa-list@matronics.com
>> Subject: Re: Europa-List: Strobe noise in radio
>>
>> I don't know what you mean when you say "chew chew"?
>> It is hard to describe a noise in words . . . =98Chew Chew=9D
is the best I can come up with I=99m afraid.
>>
>> Does it appear when receiving radio or always?
>> Always =93 whenever the radio is turned on. Volume of the noise ca
n be controlled with the Vol control.
>>
>> The "chew chew" could be the power supply charging its capacitor after ea
ch discharge?
>> Think you are right on the mark here Jan . . . . the noise immediately fo
llows the flash and it does sound like the power supply charging its capacit
or.
>>
>> How did you prove that it is radiation coupling to the antenna?
>> 1 Disconnected the power wires to the strobe unit to isolate the unit f
rom the rest of the aircraft wiring and then supplied power from a second ba
ttery direct to the strobe unit. Made absolutely no difference to the noise
.
>> 2 Disconnecting the aerial from the back of the radio completely elimi
nates the noise as does connecting an aerial from a hand held radio.
>>
>> 5V USB switchers are made to behave in the presence of AM radio mainly by
a filter on the input (2 capacitors and an inductor).
>> Sorry but you have lost me here.
>>
>> Thanks again
>> K
>
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