Roelof,
Where can I find plans for the PA0LQ filter?
Thanks,
--
73 Warren K2ORS/WD2XGJ/WD2XSH/23
FN42hi
http://www.w4dex.com/wd2xgj.htm
-------------- Original message ----------------------
From: "Roelof Bakker" <[email protected]>
> Hello Dick,
>
> PA0LQ's filter is now in wide spread use amongst NDB afficiados in favour of
> DSP filters.
> By increasing the 10 nF capacitors to 27 nF and "stagger tuning" it has been
> possible to reduce the bandwidth from 30 Hz to 6 Hz with steep slopes.
> At present I am using two of these filters in cascade, 12 Hz and 6 Hz wide
> at a centre frequency of 500 Hz.
> The fixed tuning resistors have been replaced by multiturn trimmers of 1 K.
> Aligning section 1 and 3 for maximum signal at 495 Hz and section 2 and 4 at
> 505 Hz, yields a 3 dB bandwidth of 10 Hz. This is wide enough to copy 20 WPM
> morse code.
>
> Best regards,
>
> Roelof Bakker, pa0rdt
>
>
>
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