Posted by
Guy, K2AV on
Oct 31, 2010; 4:03pm
URL: http://elecraft.85.s1.nabble.com/K3-APF-Adjustable-Q-tp5688670p5691608.html
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 <
[hidden email]> 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" <
[hidden email]>
> To: <
[hidden email]>
> 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
>>>
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