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List:       elecraft
Subject:    Re: [Elecraft] K3 APF Adjustable Q
From:       "Paul Christensen" <w9ac () arrl ! net>
Date:       2010-10-31 23:50:29
Message-ID: 42BB9184F8E648058865D56B8A83A312 () DBTOA000
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I suspect the moment variable Q were to become available, soon thereafter, 
the next request would be for variable peaking amplitude. At some point, 
Elecraft must decide what they want from APF -- is it an emulation of a 
filter used in a transceiver from twenty years ago?  Or, is it something 
more?  If it's more, then it may as well be a full-blown parametric EQ 
channel with variable amplitude, variable frequency, and variable Q.

I tend to agree with Al's comment where he noted that sometimes the most 
effective controls are the one's that are easily accessible to the op 
without the need for added manipulation.

Paul, W9AC

----- Original Message ----- 
From: "Guy Olinger K2AV" <olinger@bellsouth.net>
To: "Joe Subich, W4TV" <lists@subich.com>
Cc: <elecraft@mailman.qth.net>
Sent: Sunday, October 31, 2010 7:33 PM
Subject: Re: [Elecraft] K3 APF Adjustable Q


You've brought that up several times, Joe, but that is not the sound,
and how do you use it in CW with Shift increment at .01, particularly
with DUAL PB turning APF on and off?  73, Guy.

On Sun, Oct 31, 2010 at 4:47 PM, Joe Subich, W4TV <lists@subich.com> wrote:
>
>>> What I have been trying to point out is that there is a general
>>> benefit for a milder shape, that one MAY leave on all the time,
>>> and tweak to tight as needed.
>
> If you want a "milder" shape, use Dual PB filter with a 400 - 500 Hz
> background and 100 Hz foreground. That can certainly be left on
> all the time and the APF switched on when needed ... at least once
> all of the controls have been programmed.
>
> 73,
>
> ... Joe, W4TV
>
>
> On 10/31/2010 12:03 PM, Guy Olinger K2AV wrote:
>>
>> I'd say for variable Q, the tightest setting should be just what is
>> there now. So no one is losing anything.
>>
>> What I have been trying to point out is that there is a general
>> benefit for a milder shape, that one MAY leave on all the time, and
>> tweak to tight as needed. MP's EDSP, 450 Hz sidetone, NR=D, Contour=
>> 11 oclock as an example of a mild contour that is really helpful.
>>
>> Being able to tune the APF tight setting around allows me to match the
>> "tone" of the almost ring to the remembered tone of the weak station
>> and have it come up when I hit it.
>>
>> If the choice is sharp or no APF and no APF tune, I have to RIT the
>> station to sidetone. This has a couple of disadvantages.
>>
>> First, if running in a contest, and there are very loud stations up
>> and down (aren't there always?), RIT up and down is going to let the
>> co-channel guys in under the roofing filter and into pre-APF digital
>> space. That can't be useful. Second, continuing to tune the station
>> in becomes hard if the station stops or fades out because there is
>> nothing to "calibrate" the completion of RIT twiddle other than
>> hearing the tone from the station move to sidetone, and now it's
>> stopped or faded.
>>
>> The presence of APF tune, or variable Q does not disadvantage anyone
>> who doesn't need them, the same way all the really neat digital stuff
>> does not disadvantage the straight CW operators. The current setting
>> and shape of APF is definitely the right max Q setting, and does very
>> well for me.
>>
>> I just want a mild Q setting to imitate the shape I had with the MP
>> all those years. Those who hear it will get it, just like those that
>> hear the sharp APF for the first time and try it, get it. I think a
>> lot of people will leave a mild Q on ALL THE TIME for general
>> operating. It lowers the level of the stuff up and down a little
>> without any ringing, but still allows one to hear up and down for off
>> frequency callers. For me it's an EASIER listen for hours on end.
>>
>> 73, Guy.
>>
>> On Sun, Oct 31, 2010 at 10:47 AM, Steve Ellington<n4lq@carolina.rr.com>
>> wrote:
>>>
>>> If the caller is off frequency I would just use RIT to center him in my
>>> passband as usual and let APF do it's thing.
>>> Having used outboard APFs for years, the ability to adjust it's
>>> selectivity
>>> is very important. If the band is quiet and the signal is very weak, I
>>> would
>>> adjust the APF nearly to the point of oscillation then back it off a 
>>> tad.
>>> If
>>> the signal is weak but there is a lot of QRN, I would back off the
>>> selectivity a bit further but still take advantage of some extra peaking
>>> capability.
>>>
>>> N4LQ
>>> Steve
>>>
>>> ----- Original Message -----
>>> From: "Joe Subich, W4TV"<lists@subich.com>
>>> To:<elecraft@mailman.qth.net>
>>> Sent: Sunday, October 31, 2010 10:27 AM
>>> Subject: Re: [Elecraft] K3 APF Adjustable Q
>>>
>>>
>>>>
>>>>>> however the fixed Q has a bit of ring and at times I would like to
>>>>>> back it off (widen) it just a tad.
>>>>
>>>> This is the same mistake Yaesu made in the FT-1000D; de-Qing the
>>>> original APF made it useless in later radios. This is the very
>>>> reason not to add adjustable Q or reduce the Q of the APF currently
>>>> in field test. If you want a less aggressive filter that is centered
>>>> on the sidetone, use Dual PB ... that's exactly what it is designed
>>>> to do (and it does a very good job when used as designed).
>>>>
>>>> Adjustable center frequency is very important ... particularly when
>>>> PB CTRL is set for Shift=.05 (to allow LO-CUT-HI to function) as
>>>> the 50 Hz increments too course to tune APF using the VFO. The user
>>>> also needs the ability to adjust the peak independently in order to
>>>> peak up an off frequency caller and not "chase them up the band."
>>>>
>>>> 73,
>>>>
>>>> ... Joe, W4TV
>>>>
>>>>
>>>> On 10/31/2010 8:58 AM, Steve Ellington wrote:
>>>>>
>>>>> If I had a choice between variable center frequency and adjustable Q, 
>>>>> I
>>>>> would choose adjustable Q.
>>>>>
>>>>> My logic is: The center frequency automatically follows the sidetone
>>>>> frequency so I have no need to adjust it however the fixed Q has a bit
>>>>> of
>>>>> ring and at times I would like to back it off (widen) it just a tad.
>>>>>
>>>>> Otherwise it's a HUGE improvement, sounds great and I wish to thank
>>>>> those
>>>>> who made it possible.
>>>>>
>>>>> 73
>>>>> N4LQ
>>>>> Steve
>>>>>
>>>>> ______________________________________________________________
>>>>> Elecraft mailing list
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>>>>>
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>>>>>
>>>> ______________________________________________________________
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>>>>
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>>>
>>> ______________________________________________________________
>>> Elecraft mailing list
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>>>
>>
>
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