>From what I've seen (these are all duals, there are also quad versions of
most?) the NE5532 is noted for a good price/performance (low noise) ratio for
an AF active filter. The LM833, TL072/82, and NJM2068 might also possibly be
good candidates. Even the lowly LM358 might be usable with the caveat of
adding a pull down resistor (drawing about 1 ma) to eliminate crossover
distortion. (Info per ARRL's EMRFD p. 3.25.)
Disclaimer: as they say, YMMV....
73, Al
On Wed March 23 2016 12:03:01 pm Tim wrote:
> I copied the 208 filter as well, even etched the pc board. I wired it
> for the 515 and gave it to my Dad for Christmas one year. I have that
> filter, but I know the chip isn't made anymore. I would guess that an
> ordinary audio op amp would work. So yeah we can see what someone else
> might suggest.
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