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Calc freqs of triple tuned bandpass filters?

Started by BobG May 27, 2010
On 5/27/2010 3:30 PM, Rune Allnor wrote:
> On 27 Mai, 21:25, Jerry Avins<j...@ieee.org> wrote: > >> I remember doing the math for stagger-tuned IF strips in the early >> 1050s. > > Er...?
I was only one key off. :-) Jerry -- Engineering is the art of making what you want from things you can get. &#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;
Jerry Avins  <jya@ieee.org> wrote:

>On 5/27/2010 3:57 PM, Steve Pope wrote:
>> Sure. Tune precisely to a strong RF signal, and trim the >> little IF filters until you see a maximum at their output >> on a scope.
>That gets you maximum sensitivity at the expense of distortion at higher >volumes. Low distortion is achieved by stagger tuning to broaden the >response. This is best done with a sweep generator, but if one is good >at it (I was once) it can be done fairly well by ear.
I totally forgot about "stagger tuning". Yes, you do not want all your pole pairs at the exact same place to get a nice flat passband.
>> I haven't done this for maybe 40 years but that doesn't >> mean it isn't still done.... > >It's been longer than that for me.
Steve
On May 27, 2:14&#2013266080;pm, BobG <bobgard...@aol.com> wrote:
> Whats the rule of thumb for how far to detune the two outside filters > for third octave bandwidth? Is the middle filter supposed to have a > little less gain to flatten the passband out? Is the Q of all 3 > filters the same? Do the skirts roll off at 18dB per octave? (I > searched for 'triple tuned' but no hits, so I hope I dont get flamed > for asking)
Most here have given the answers, but if you wish to look at analog approximations, the "Active Filter Cookbook" (Don Lancaster) has great tables, nomographs, and design guidelines for stagger tuning. Clay
On May 27, 4:32&#2013266080;pm, Jerry Avins <j...@ieee.org> wrote:
> On 5/27/2010 3:30 PM, Rune Allnor wrote: > > > On 27 Mai, 21:25, Jerry Avins<j...@ieee.org> &#2013266080;wrote: > > >> I remember doing the math for stagger-tuned IF strips in the early > >> 1050s. > > > Er...? > > I was only one key off. :-) >
i dunno Jerry. yer older than me and i date back to the 1050s. January 1, 1056, in fact. after reading and hearing "OIL SPILL"..."BP"..."MASSIVE ENVIRONMENTAL DAMAGE"..."EUROZONE COLLAPSE"..."STOCK MARKET IN THE TOILET"..."IT'S ALL OBAMA'S FAULT"..., i need a giggle before going to bed. g'night all. with any luck, there will be a world waiting for us in the morning. r b-j
On 5/27/2010 11:30 PM, robert bristow-johnson wrote:

   ...

Hey, Kid, I was 4 years out of high school when you were born, then. Had 
I followed a normal path, I'd have been a college senior.

> after reading and hearing "OIL SPILL"..."BP"..."MASSIVE ENVIRONMENTAL > DAMAGE"..."EUROZONE COLLAPSE"..."STOCK MARKET IN THE TOILET"..."IT'S > ALL OBAMA'S FAULT"..., i need a giggle before going to bed. > > g'night all. with any luck, there will be a world waiting for us in > the morning.
Good night! Jerry -- Engineering is the art of making what you want from things you can get. &#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;&#2013266095;