I absolutely need to get on with things as well.
Cheers.
Jan
On 12/24/2015 2:20 PM, Kingsley Hurst wrote:
> 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 flight 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
> <mailto: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; interfere badly with AM radio like our COM. Mitigation
>> involves a filter on their 12V input and on their 5V output. Even so
>> a cheap switcher radiates and degrades radio reception.
>>
>> If what we hear is the charging of the capacitor the source should be
>> the input power lines or the (transformer in) the box, not the output
>> wiring to the strobe.
>> With the box located at the bagage bay station it would then seem
>> strange that 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 dipole with a 50 ohm dummy load.
>>
>> Jan
>>
>> On 12/23/2015 11:24 PM, Kingsley Hurst wrote:
>>> RON I do have twisted pair power supply lines to the strobe power
>>> supply thanks.
>>> PETE Thanks for that tip . . . . . LED Strobe will be considered
>>> if all else fails.
>>> JAN Comments / answers embedded below . . . .
>>> Thank you all
>>> Kingsley
>>> *From:* Jan de Jong <mailto:jan_de_jong@casema.nl>
>>> *Sent:* Wednesday, December 23, 2015 7:36 PM
>>> *To:* europa-list@matronics.com <mailto: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 . . . Chew Chew is the
>>> best I can come up with Im afraid.*
>>>
>>> Does it appear when receiving radio or always?
>>> *Always whenever the radio is turned on. Volume of the noise can
>>> be controlled with the Vol control.*
>>> The "chew chew" could be the power supply charging its capacitor
>>> after each discharge?
>>> *Think you are right on the mark here Jan . . . . the noise
>>> immediately follows the flash and it does sound like the power
>>> supply charging its capacitor.*
>>>
>>> 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 from the rest of the aircraft wiring and then supplied power
>>> from a second battery direct to the strobe unit. Made absolutely no
>>> difference to the noise.*
>>> *2 Disconnecting the aerial from the back of the radio completely
>>> eliminates 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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