[1000mp] Noise on MKV RX Audio

[W7RY]

Nothing a brute force capacitive inductive filter cant fix. A Simple low
current automotive filter should do the trick. Or get out the calculator
out or just try a few values of small inductance and large amount of
capacitance. (1000Mf +). 

My guess it that the fan itself is AC. There is a small inverter circuit
that makes AC from the DC supply to run the fan. All small DC fans have
AC motors and an inverter circuit. That way the motor can be brushless.

I have had this same issue with repeaters. Just hooking a small DC
cooling fan up to any old DC source produces noise in the audio
circuits. Either move the fan supply lines closer to the power supply
filter capacitors, or install a small filter.


Good luck

73
Jim W7RY



-----Original Message-----
From: 1000mp-bounces at mailman.qth.net
[mailto:1000mp-bounces at mailman.qth.net] On Behalf Of D. J.
Sent: Sunday, December 11, 2005 5:32 PM
To: All about Yaesu 1000mp
Subject: Re: [1000mp] Noise on MKV RX Audio


On 11, Dec 2005, at 19:07, Paul Baldock wrote:

> At 04:08 PM 12/11/2005, D. J. wrote:
>
>> I noticed this also on two MKVs.  I doubt Yaesu will be of much
>> help.  Maybe the next generation radio will be free of this, FT-2000?
>> Dale J.
>
> Did you notice if the ripple caused by the fan on 13V supply  
> introduced modulation on a received carrier, as it does on mine?  
> Ripple is not necessarily a problem so long as circuits connected  
> to that supply are not affected it.
>
> Paul

I only noticed it was more pronounces with the processor on.  I had a  
MKV right out of the box with it and sent it back.  I forgot what  
they told me, but mainly they said it was common on the MKV. 
  
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