Today's Message Index:
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1. 07:43 AM - Re: turn coordinator causing noice in headset (jerrytex)
2. 08:09 AM - Re: Re: turn coordinator causing noise in headset (Roberto Waltman)
3. 09:00 AM - Re: Re: turn coordinator causing noise in headset (Robert L. Nuckolls, III)
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Subject: | Re: turn coordinator causing noice in headset |
No I have not hooked up the T/C to a seperate power supply. I'll try that as soon
as I can and report back.
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=386038#386038
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Subject: | Re: turn coordinator causing noise in headset |
jerrytex wrote:
> The noise is there always, regardless of transmitting or receiving. I can put
my headset on, turn on the master, listen to the gyro spin up in the headset,
then turn on the landing the light, and the noise goes away.
An uneducated guess: The noise is introduced via the supply bus, and
turning the light on somehow provides a lower impedance path to ground
that attenuates it. The suggestion to add capacitors sounds good, how
many and where, that's a different story.
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Subject: | Re: turn coordinator causing noise in headset |
At 10:07 AM 10/26/2012, you wrote:
>
>jerrytex wrote:
>>The noise is there always, regardless of transmitting or receiving.
>>I can put my headset on, turn on the master, listen to the gyro
>>spin up in the headset, then turn on the landing the light, and the
>>noise goes away.
>
>An uneducated guess: The noise is introduced via the supply bus, and
>turning the light on somehow provides a lower impedance path to
>ground that attenuates it. The suggestion to add capacitors sounds
>good, how many and where, that's a different story.
It's an intriguing symptom. The hypothesis has
some weight. Waaayyyy back when, we believed that
a battery offered an effective electromotive mass
across the bus. That bubble burst when I was
fine tuning the feedback loops on the B&C linear
regulators. With a bus voltage above battery-delivery
potential; greater than 12.5 volts and less than
battery-charging potential; less than 14.0 volts,
the battery is essentially 'open circuit'.
The most challenging condition for bench marking
regulator performance was with a fully charged battery
and relatively light loads. Turning a even a 55w
landing light on would appear as a parallel
impedance on the order of 3 ohms . . . perhaps
significant in comparison with the sum of impedances
in this system.
It would be interesting to probe the system with
some test equipment . . .
If this antagonist is propagating through the
power leads, then an L/C filter having inductance
facing the T/C is called for. The interesting
detail is a notion that the noise spectrum
covers VHF frequencies and gets into the victim
via the antenna. This suggests that relatively small
values of L/C would be effective.
Bob . . .
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