Re: Fwd: New Sherwood report

Posted by Jan Erik Holm on Dec 03, 2010; 2:44pm
URL: http://elecraft.85.s1.nabble.com/Fwd-New-Sherwood-report-tp5793377p5800055.html

So now we have a 2 ms claim for the K3. I know I measured
it to 5 ms but this was something like 2 years ago.

What is it? Can Elecraft please tell.

And yes dynamic testing of SSB IMD is the only way to
go when dealing with a ALC/AGC controlled TX.

Jim SM2EKM
----------------
On 2010-12-03 15:08, Paul Christensen 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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