Wayne Burdick wrote:
Joe Subich, W4TV wrote:
Remember, IMD is driven by total *peak* signal level. The peak signal
level is not simply the scalar sum of the levels ... it is a vector
sum as the individual signals add in phase.
And those peaks could be slightly modulating the AGC loop.
Joe,
You may recall that the subject of K3 Mush was discussed on the K3
Contesters Forum earlier this year, and that I suggested that the Group
Delay Variations introduced by the narrower bandwidth roofing filters might
well be the cause of the Mush problem. The recordings of K3's audio sent
wayne burdick wrote
Hi all,
The K3's hardware AGC time constant is a compromise between recovery
time and IMD due to modulation of the loop. C238, on the bottom of the
RF board near the front, sets this time constant.
We did a little experiment today . . .
I think it would be
mod.
73,
Fred KE7X
Fred Cady
fcady at ieee dot org
-Original Message-
From: elecraft-boun...@mailman.qth.net [mailto:elecraft-
boun...@mailman.qth.net] On Behalf Of Wayne Burdick
Sent: Sunday, December 04, 2011 6:59 PM
To: Elecraft Reflector
Subject: Re: [Elecraft] K3 hardware AGC
Just for comparison and I don't have the K3 that we used unpacked yet so
I don't know the agc settings.
I use AFX all the time. ATT was almost never engaged. I never use RX
equalization. RF gain was used mostly on the low bands.
When I had Bose headphones I noticed that they were quite
Nice idea, Barry, but probably continuously flashing something on the
display should be an easier solution from a firmware mod point of view.
Maybe flashing the 'F' of the AGC on the display, or something similar.
That should be straightforward and doesn't require any physical
modification to
Fred's configuration struck me as quite surprising. With DSP at
5-700, his K3 would be using the 1000 kHz roofing filter, so there
would be a substantial frequency range blocked only by the DSP. And
ATT on -- why would this be attractive? I'd think to hear weak
signals close together, you'd
...@mailman.qth.net] On Behalf Of Peter Wollan
Sent: Monday, December 05, 2011 11:45 AM
To: Elecraft Reflector
Subject: Re: [Elecraft] K3 hardware AGC experiment shows promise (
KE7Xconfig)
Fred's configuration struck me as quite surprising. With DSP at
5-700, his K3 would be using the 1000 kHz roofing
Subject: Re: [Elecraft] K3 hardware AGC experiment shows promise
By the way, we'll be happy to send out these surface-mount 1 uF
capacitors (or whatever we determine is the best value) to anyone who
would like to try the experimental mod, immediately and at no charge.
These are huge as SMD
It's always a good idea to present the lowest-level of RF energy to the
receiver input. If you can hear the band noise, any more gain at the RF is
wasted and can result in various issues with strong signals near or in the
passband. On the lower HF bands, the band noise is usually perfectly audible
fcady at ieee dot org
-Original Message-
From: elecraft-boun...@mailman.qth.net [mailto:elecraft-
boun...@mailman.qth.net] On Behalf Of Wayne Burdick
Sent: Sunday, December 04, 2011 6:59 PM
To: Elecraft Reflector
Subject: Re: [Elecraft] K3 hardware AGC experiment shows promise
, December 04, 2011 8:50 PM
Subject: [Elecraft] K3 hardware AGC experiment shows promise
Hi all,
The K3's hardware AGC time constant is a compromise between recovery
time and IMD due to modulation of the loop. C238, on the bottom of the
RF board near the front, sets this time constant.
We did
...@elecraft.com
To: Elecraft Reflector elecraft@mailman.qth.net
Sent: Sunday, December 04, 2011 8:50 PM
Subject: [Elecraft] K3 hardware AGC experiment shows promise
Hi all,
The K3's hardware AGC time constant is a compromise between recovery
time and IMD due to modulation of the loop. C238
Hi all,
The K3's hardware AGC time constant is a compromise between recovery
time and IMD due to modulation of the loop. C238, on the bottom of the
RF board near the front, sets this time constant.
We did a little experiment today (thanks to Tree, N6TR) that suggests
increasing the size of
By the way, we'll be happy to send out these surface-mount 1 uF
capacitors (or whatever we determine is the best value) to anyone who
would like to try the experimental mod, immediately and at no charge.
These are huge as SMD parts go. Anyone with a fine-tip iron would have
no trouble
, KPA-500 #161
- Original Message -
From: Wayne Burdick n...@elecraft.com
To: Elecraft Reflector elecraft@mailman.qth.net
Sent: Monday, December 05, 2011 11:50 AM
Subject: [Elecraft] K3 hardware AGC experiment shows promise
Hi all,
The K3's hardware AGC time constant is a compromise
Some ops have mentioned problems with signals much lower than this,
which has always baffled me.
Remember, IMD is driven by total *peak* signal level. The peak signal
level is not simply the scalar sum of the levels ... it is a vector
sum as the individual signals add in phase. W8FN
Joe Subich, W4TV wrote:
Remember, IMD is driven by total *peak* signal level. The peak signal
level is not simply the scalar sum of the levels ... it is a vector
sum as the individual signals add in phase.
And those peaks could be slightly modulating the AGC loop.
Wayne
This is why I bought an Elecraft. Good luck getting this type of
support with IKY. I would try the mod but since I haven't noticed the
issue, I don't think it makes sense for me to try.
We were not digging signals out of the mud in J6 except for 160 but
nobody mentioned any issues.
On
I should point out that the very common habit of not using the ATT or
even turning on the PRE on lower bands would be commonly putting this
circuit in this condition. Perhaps that is why there is a contingent
of us that never seems to have the problems reported. Constantly
running the RF end at
I find those comments exceptionally interesting, Joe.
a. it might help explain why keyed CW signals seem (in my experience,
at least) to be a bigger issue .. more yanking around of the AGC.
b. it might help explain why at least some of us feel that the issue is
worse for weaker signals.
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