[Elecraft] K3S audio board for K3 upgrade?

[Ian White]

Don wrote:

>Gene (and all),
>
>Yes, the AGC settings do help a lot.  The K3/K3S has enough gain that
>often the AGC is activated on the atmospheric noise in the band.

It isn't so much that the K3/K3S has "gain", but that the factory
default AGC THReshold is so very, very low. Measurements by KE7X [1]
have shown that the default setting of THR=5 corresponds to an AGC onset
at less than S3, whereas competing rigs have a threshold of S7 or even
higher. This very low AGC threshold is what allows the AGC to be
activated by band noise.

Elecraft's factory defaults of THR=5 and SLP=12 compress all signals
above the AGC threshold into a very narrow range of audio output levels
[see the measurements by KE7X]. This makes for comfortable
broadcast-style listening - but there is price to be paid. The default
settings greatly reduce the differences in the *true* strengths of
incoming signals - important differences that DXers and contesters
*need* to hear, in order to pick individual signals out of a pileup.

Following complaints from DXers, DXpeditioners and contesters about this
so-called "pileup mush", and following further series of measurements by
KE7X, Elecraft eventually did increase the available range of AGC
THReshold settings (the v4.51 firmware upgrade). 

Following the release of FW v4.51, consensus within the [K3-contesting]
Yahoo group about the most important settings for DXing and contesting
has been as follows. 

* AGC THR: increase to at least 8 (from default = 5) and preferably to
12 or even 14 if your ears can handle the increased range of audio
levels [2].

* AGC SLP: decrease to 8 or even less (from default = 12). Lower SLP
settings allow stronger signals to sound somewhat louder, and thus more
realistic, but the range of variation will be partly determined by the
THR setting already made; so always experiment with THR first, and with
SLP afterwards. 

* AGC DCY = SOFT (not default=NOR). The User Manual claims that "The
SOFT setting can reduce IMD caused by traditional AGC, and is especially
useful in 'pileup' conditions, in some cases making it unnecessary to
turn AGC off."
 
The settings recommended above have essentially solved the problem of
"pileup mush" for those who have tried them... but regrettably, Elecraft
has done almost nothing to make DXers and contesters  aware that such
changes are possible. 
 
More than 3 years after the firmware release notes boasted that v4.51
"greatly improves signal clarity in pile-ups and other high-noise or
dense-signal situations, especially with threshold set to 12 or higher",
that information is *still* missing from the User Manual. There is also
no information on how to create different 'profiles' of AGC settings for
different types of users.

Meanwhile, Elecraft's factory AGC defaults remain exactly as they were,
still optimized apparently for comfortable 'listening', while many DXers
and contesters remain unaware that their K3/K3S could actually be *so*
much better. 



[1] http://www.ke7x.com/home/miscellaneous-k3-information

[2] It is important to give any increased AGC THReshold setting an
extended trial. To anyone accustomed to an artificially restricted range
of audio signal levels, a higher setting will initially sound quite
'aggressive' -even though the new setting is much closer to real life. 


73 from Ian GM3SEK


>-----Original Message-----
>
>On 3/22/2016 6:32 PM, Gene Gabry wrote:
>> This has been an interesting thread to which I have experimented a
bit
>more
>> and found the AGC setting recommendations from a couple of posters to
>be
>> very valuable, and Eric's suggestions on BW settings to be a nice
>compliment
>> to play with. Although, my ears still like a little HF, I like the
sound of
>> a BW from 100hz to 2.7khz for SSB and usually the 500hz filter set to
>300hz
>> with DSP. I now have AGC THR set to max and AGC SLP set to 0. I also
set
>RX
>> EQ to flat and use hi/lo cut when needed. Really cuts down on the
high
>> frequency hash I get from this qth. I leave the AGC settings the same
for
>> SSB and CW and play with BW and cut between the two modes, depending
>on
>> conditions.
>>
>
>______________________________________________________________
>Elecraft mailing list
>Home: http://mailman.qth.net/mailman/listinfo/elecraft
>Help: http://mailman.qth.net/mmfaq.htm
>Post: mailto:Elecraft at mailman.qth.net
>
>This list hosted by: http://www.qsl.net
>Please help support this email list: http://www.qsl.net/donate.html
>Message delivered to gm3sek at ifwtech.co.uk