[TenTec] Switched audio filters

[Jim Allen]

Auto correct is my worst enema.  Either that or one of these days, I should learn to twype.

73 de W6OGC Jim Allen 

Sent from my iPad

> On Mar 23, 2016, at 22:55, Al Gulseth <wb5jnc at centurytel.net> wrote:
> 
> AH-1 or AF1?
> 
> 73, Al
> 
>> On Wed March 23 2016 10:51:18 pm Jim Allen wrote:
>> I just built an audio filter from Elecraft, AH-1.  It went together on a
>> Sunday afternoon, so easy even a lawyer could do it, and if I had known how
>> well it worked, how much it helps digging out weak signals, I would have
>> built it before now.
>> 
>> 73 de W6OGC Jim Allen
>> 
>> Sent from my iPad
>> 
>>> On Mar 23, 2016, at 22:15, Al Gulseth <wb5jnc at centurytel.net> wrote:
>>> 
>>> 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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