> I'm still in a quandry :)
I am too <G>. The measured results are rather clear but I
miss the "magic" results I saw with 4.16 ...
The "feeling" I get with 4.21 is that the Q has been reduced
compared to 4.16 but since the quantitative data shows that's
obviously not the case, I'll just need to continue working
with it to see if I can regain the magic. Maybe it is just
conditions ... noise levels have been a lot lower the last
couple days but there haven't been as many weak signals either.
73,
... Joe, W4TV
On 11/13/2010 11:48 PM, Wayne Burdick wrote:
> Joe,
>
> If Lyle is using the same algorithm as before, and your results are as
> indicated below (virtually a tie), I don't understand how you could be
> 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
> people testing, and only two or three have perceived a difference, so
> given the statistical evidence, I'd suggest that background noise
> conditions are the variable here, not the firmware. Lyle has also
> completely reviewed the DSP implementation -- no change.
>
> But since the customers are always right, I'm still in a quandry :)
>
> tnx
> Wayne
>
> On Nov 13, 2010, at 6:27 PM, Joe Subich, W4TV wrote:
>
>>
>>>> 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: w5...@cybermesa.net
>>>> To: li...@subich.com; elecraft@mailman.qth.net
>>>> 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: elecraft@mailman.qth.net
>>>> 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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>>>
>> ______________________________________________________________
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>
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