[AMPS] Dirty Output

[Steve Thompson]

-----Original Message-----
From: Firson Maryutenli <firson@hotmail.com>
To: amps@contesting.com <amps@contesting.com>
Date: 21 May 2001 03:32
Subject: [AMPS] Dirty Output


>
>Hello..
>
>I was building pre amp. to drive 4-400A in class AB1 for radio frequencies
>in 3.800 Khz. The pre amp is 6L6 in class A with passive grid input, and
>have tuned output in 3.800 Khz.
>
>The problem is, I was feeding relative clean signal in grid of 6L6 (the
>nearest harmonic in 3.930 Khz minus 70 db below desired signal 3.800 khz).
>But the output result in 6L6 there is sporious generated in 3.825 Khz,
3,850
>Khz, 3.875 with peak only minus 20 db under desired signal in 3.800 Khz.


Sounds like it is oscillating at 25kHz. Try a different valve, and check the
lf decoupling. Try putting a few ohms resistance in series with any lf
capacitors.

Steve


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