hearing a "lack of ringing" in the new revision. I simply cannot hear
any difference myself, and I'm extremely picky. We have nearly 100
conditions are the variable here, not the firmware. Lyle has also
>
>>> I'll count this as another vote in favor of adding the Variable Q
>>> setting...
>
> Not on your life. The lack of ringing on the newer version seems to
> go along with a general decline in effectiveness. If anything I'd
> prefer to see higher Q.
>
> Just for grins I reloaded 4.16 to make the same measurements using the
> XG-2 as I made on 4.21. Here is the comparison:
>
> BW 4.21 4.16
> -------------------------
> 0 dB 1 2 Hz
> -1 dB 8 9 Hz
> -6 dB 31 31 Hz
> -10 dB 52 49 Hz
> -20 dB 165 162 Hz
> -30 dB 345 351 Hz
> Gain 9.0 9.1 dB
>
> Unlike W4ZV, I found only a 3 Hz offset in 4.16 (the peak response
> was 3 Hz above zero beat - or the indicated spot/shift frequency).
> Even though the test results were generally the same within the
> measurement tolerances, I still feel the 4.16 version was more
> effective
> in on air listening.
>
> These measurements were generated with an XG-2 set for 1 uV with the
> K3 attenuator engaged for an effective signal level of -118 dBm.
>
> 73,
>
> ... Joe, W4TV
>
> On 11/13/2010 8:07 PM, The Smiths wrote:
>>
>> I'll count this as another vote in favor of adding the Variable Q
>> setting... At least a choice of 3 perhaps Wide, Med and Narrow.
>> Even if one perceives the APF as "less ringy" and comments on it
>> being a good thing, that means that they are happy to know that the
>> Q got widened out a little, and things seem to sound "better".
>>
>>> From:
[hidden email]
>>> To:
[hidden email];
[hidden email]
>>> Date: Sat, 13 Nov 2010 21:19:46 +0000
>>> Subject: Re: [Elecraft] K3 APF
>>>
>>> Joe wrote:
>>>
>>>> I did not make similar measurements with the original alpha
>>>> test version but this version seems subjectively less tight
>>>> than the original ... there is certainly less ringing with
>>>> this one but signals did not seem to "pop" like they did on
>>>> the earlier version when I tried it last night on 160/80/40.
>>>
>>> Joe, I agree with your subjective observation. No, the signals
>>> don't "pop"
>>> as much -- but there is less ringing. This is a trade-off, of
>>> course, and
>>> the precise balance of peak gain versus ringing is always going to
>>> be a
>>> matter of personal preference.
>>>
>>> I like this less-ringy version better, I think. Haven't had time
>>> to play
>>> with it a lot yet, but I will. I'm sure we will see many other
>>> opinions. So
>>> far, I think the current version is very smooth and adequately
>>> "peaky".
>>>
>>> (Opinion subject to revision upon more extensive usage.)
>>>
>>> Bill W5WVO
>>>
>>>
>>> -----Original Message-----
>>> From: Joe Subich, W4TV
>>> Sent: Saturday, November 13, 2010 20:35
>>> To:
[hidden email]
>>> Subject: Re: [Elecraft] K3 APF
>>>
>>>
>>> I made a similar set of measurements ... using the XG-2 and
>>> the AFV/dBV capability ...
>>>
>>> I measure the peak at 1 Hz wide (e.g. -.1dB +/- 1 Hz)
>>> the 1 dB points are 8 Hz wide
>>> the 6 dB points are 31 Hz wide
>>> the 20 dB points are 165 Hz wide
>>> the 30 dB points are 345 Hz wide
>>> gain is right at 9 dB.
>>>
>>> The measurements were made on 40 Meters with the XG-2 set to
>>> 1 uV and the K3 attenuator activated yielding a -108 dBm test
>>> signal.
>>>
>>> I did not make similar measurements with the original alpha
>>> test version but this version seems subjectively less tight
>>> than the original ... there is certainly less ringing with
>>> this one but signals did not seem to "pop" like they did on
>>> the earlier version when I tried it last night on 160/80/40.
>>>
>>> 73,
>>>
>>> ... Joe, W4TV
>>>
>>>
>>> On 11/13/2010 1:24 PM, Bill W4ZV wrote:
>>>>
>>>> For my own curiosity I did some measurements of the latest APF.
>>>> They agree
>>>> with
>>>> measurements of the first release with the exception that the
>>>> filter peak
>>>> is
>>>> now
>>>> zero beat instead of +10 Hz:
>>>>
>>>> Zero beat = 7040.021
>>>> Flat passband = 021-020 (both 0.0 to -0.1 dB)
>>>> -1 dB passband = 026-018 (-1.2 dB and -0.8 dB)
>>>> -6 dB passband = 037-009 (-5.8 and -6.0 dB)
>>>>
>>>> Flat = 2 Hz BW (at zero beat)
>>>> -1 dB = 8 Hz BW
>>>> -6 dB = 28 Hz BW
>>>>
>>>> I didn't measure the -6 dB BW carefully on the first pass since I
>>>> was more
>>>> interested in the -1 dB BW, but this looks similar and agrees
>>>> with Lyle's
>>>> 30
>>>> Hz
>>>> design goal. As mentioned previously, the -1 dB BW is important
>>>> when
>>>> trying
>>>> to
>>>> detect signals below the noise floor since the human ear can
>>>> detect this
>>>> difference in marginal conditions.
>>>>
>>>> I also checked the gain (APF vs not) which I didn't do before...
>>>> +9.1 dB
>>>> which is
>>>> very close to Lyle's design goal of +9 dB.
>>>>
>>>> Nice job Elecraft!
>>>>
>>>> 73, Bill
>>>>
>>>>
>>> ______________________________________________________________
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