[1000mp] Noise on MKV RX Audio

[W7RY]

-----Original Message-----
From: 1000mp-bounces at mailman.qth.net
[mailto:1000mp-bounces at mailman.qth.net] On Behalf Of Paul Baldock
Sent: Wednesday, December 14, 2005 2:40 PM
To: All about Yaesu 1000mp
Subject: RE: [1000mp] Noise on MKV RX Audio

At 01:56 PM 12/14/2005, you wrote:
>Directly across the leads to the fan as close to the fan as possible.

I don't think this a good idea. The fan is switched by a transistor.
That is of no matter. The capacitor will just charge a little slower.

>If that does not work, try installing a small choke in series with the
>fan.
A choke without a capacitor is useless. 
A 6 mH choke works well.
And a ~470 to 1000 MF capacitor.

However, because I also see Audio on the 13V supply when 
transmitting, rather than tackling the noise from the fan alone, its 
probably better to add decoupling to the 13V supply.

Then there is two problems. Having the fan generated hash on the DC buss
is most likely causing more problems than the audio.  

You are correct; the audio should also be properly decoupled.

73
Jim W7RY


Paul



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