http://elecraft.85.s1.nabble.com/Fwd-New-Sherwood-report-tp5793377p5806131.html
eliminate AGC generated clicks on break ... it will only
... Joe, W4TV
> Yes 99% of all CW stations clicks at the "break" side.
>
> I didn´t think about the ALC but that is right, thanks.
>
> However by increasing the envelope fall time we will
> "help" a bad ALC system if you understand what I mean.
>
> Anyway I better can this before HHQ puts the lid on.
>
> /SM2EKM QRT
> ------------------
> On 2010-12-03 19:18, Joe Subich, W4TV wrote:
>>
>> > Waveform? When you have a 1 ms raise/fall time no way you
>> > can shape the waveform so it doesnt click.
>>
>> That's not the case. If the first and second derivatives of
>> the power output are minimized, the waveform does not click.
>> There are many studies about bandwidth vs. rate of change in
>> digital modulation that will provide the information to show
>> that principle.
>>
>> In the specific case of CW as long as the transitions from
>> the "rise" to the steady "on" state and from the steady "on"
>> state to the fall are properly shaped (first/second derivative
>> minimized) the apparent clicks will be minimized.
>>
>> The traditional "feedback" ALC system almost guarantees clicks
>> on the *trailing edge* of the CW element. Traditional ALC
>> attempts to maintain the output as the key is opened and will
>> increase system gain as the driving waveform starts to decay.
>> The output level will only begin to fall when the ALC gain
>> has reached maximum - at which point there will be a major discontinuity
>> in the waveform. A properly designed feedback
>> ALC system would be incorporate sample and hold to maintain
>> steady system gain during the "ramp up" and "ramp down" parts
>> of the CW waveform to prevent the "corner sharpening."
>>
>> Again, rise time controls the basic CW bandwidth but "clicks"
>> are a feature of discontinuities in the CW envelope. Please
>> do not confuse the two.
>>
>> 73,
>>
>> ... Joe, W4TV
>>
>> On 12/3/2010 9:46 AM, Jan Erik Holm wrote:
>>> Waveform? When you have a 1 ms raise/fall time no way you
>>> can shape the waveform so it doesnt click.
>>>
>>> /Jim SM2EKM
>>> ---------------
>>> On 2010-12-03 15:29, Guy Olinger K2AV wrote:
>>>> All the click complaints for years and still Yaesu doesn't take care
>>>> of the waveform. It's not like there aren't tons of reads on the
>>>> subject, no excuse at all since Google. It's more like they just
>>>> don't care, or are simply convinced it doesn't matter. After all,
>>>> isn't CW obsolete, and nobody uses it anymore, right?
>>>>
>>>> 73, Guy.
>>>>
>>>> On Fri, Dec 3, 2010 at 9:08 AM, Paul Christensen<
[hidden email]> wrote:
>>>>> 4 ms. Given that the FTdx5K rise/fall is roughly double the time of the
>>>>> K3 -- and that the K3 at 2 ms consumes significantly less bandwidth
>>>>> than the
>>>>> FTdx5K at 4 ms, the CW transmit quality of the K3 is far superior. I
>>>>> would
>>>>> like to hear QSK on the Yaesu, compare it with the K3's QRQ mode,
>>>>> and note
>>>>> any audible artifacts in the headphones -- especially for signs of
>>>>> clicks
>>>>> and DC thumps.
>>>>>
>>>>> Referring to the December, 2010 QST Product Review on p.45, take a
>>>>> look at
>>>>> the leading edge of the second pulse (lower trace) in Figure 1. The
>>>>> sharp
>>>>> rise and sharp edge at the top of the waveform is what is consuming the
>>>>> bandwidth. Based on that waveform, it was absolutely generating
>>>>> clicks at
>>>>> some distance from the Fc. That pattern is characteristic of a
>>>>> deficient
>>>>> ALC system.
>>>>>
>>>>> A deficiency in the ALC system then takes us into SSB Tx IMD. The
>>>>> published
>>>>> FTdx5K Tx IMD numbers look great with the ARRL's steady tone method but
>>>>> arguably, that's probably more relevant to data modes. The question is
>>>>> "what is the FTdx5K's ALC doing to undermine the rig's otherwise
>>>>> excellent
>>>>> SSB Tx IMD numbers, especially in Class A?" Really, the published Tx
>>>>> IMD
>>>>> figures are meaningless unless dynamic testing is conducted to simulate
>>>>> rapid changes in power associated with voice modes.
>>>>>
>>>>> Paul, W9AC
>>>>>
>>>>> ----- Original Message -----
>>>>> From: "Jan Erik Holm"<
[hidden email]>
>>>>> To:<
[hidden email]>
>>>>> Sent: Friday, December 03, 2010 8:27 AM
>>>>> Subject: Re: [Elecraft] Fwd: New Sherwood report
>>>>>
>>>>>
>>>>>> Yes but to what rise/fall time was the radio set? AFAIK in
>>>>>> the FT5000 it can be changed.
>>>>>>
>>>>>> /Jim SM2EKM
>>
>>
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