Barry,
The values presented by me is for everyone building and not a
solution to your issue but
it may improve it.
Please look for component issues, if pop corn noise if present is
a component failure.
Raj
On 04/09/2022 5:44 PM, barry halterman
wrote:
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Raj, the MDS at 7MHZ is 10uv. A 50uv signal
is as loud as the mixer noise.
Barry
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Sent from for Windows
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From:
Raj vu2zap
Sent: Sunday, September 4, 2022 12:51 AM
To: [email protected]
Subject: Re: [BITX20] Daylight again radio audio
filter
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The original on LTSpice turned up with a 10KHz roll off which
is too high. So
changed values with suggestions from Farhan till it looked
right at 3-4KHz.
This should reduce high freq whines and hiss.
Raj
On 03/09/2022 7:03 PM, barry halterman
wrote:
Raj, Thanks for the information on the
sullen-key filter. I never heard of this design before and
found that it has been around for quite some time. Just goes
to show the amount of intellect in this group.
73
Barry
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Sent from for Windows
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For better results change the following
values and try:
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R27, 28, 31, 32, 35 & 36 to 2.2K
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C32, 33 & 37 to 0.047u or 0.05u
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C51,53 & 55 to 0.01
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The filter is Sallen key low pass and
after mod will have
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roll off just below 5KHz
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Raj
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Raj vu2zap