[Elecraft] K3 Signal blocking inside of the crystal filter BW

[Dave Hachadorian]

I'm sure the Elecraft crew will respond to your post, but 
here are my recommendations. Load the latest beta firmware 
and try the settings below, in my order of preference. In 
all cases, the most important setting is to keep the RF Gain 
turned down as low as possible, allowing you to just barely 
hear the weakest signals clearly. A 200 Hz filter may help a 
little, but not much if you are dealing with a pileup of 
closely-spaced signals.

1.
AGC=OFF
AF LIM=nor 030
Headphones plugged into speaker jack (to avoid tripping the 
K3's ugly AF limiter)
AF gain at about 10 o'clock (or whatever it takes to protect 
your ears on the loudest signals)

2. (uses new AGC HLD and AGC DCY=soft functions)
AGC=SLOW
AGC DCY=SOFT
AGC HLD=0.2
AGC PLS=NOR
AGC SLP=0
AGC THR=008
AGC-F=200
AGC-S=20

3. (uses new AGC DCY=SOFT function)
Same as 2 above, except AGC=FAST

Dave Hachadorian, K6LL
Yuma, AZ



----- Original Message ----- 
From: "Dave Anderson, K4SV" <davek4sv at yahoo.com>
To: <Elecraft at mailman.qth.net>
Sent: Friday, March 27, 2009 3:43 PM
Subject: [Elecraft] K3 Signal blocking inside of the crystal 
filter BW



Hi All,

I recently purchased a brand new K3 and after a factory 
tuneup, it is a very nice radio.

I discovered a situation using it that I would like to 
mitigate.

When trying to work a station simplex in a pileup I 
experienced receiver blocking. While trying to listen to the 
DX station others were calling so I narrowed the passband 
down to 200hz. I was unable to copy the weaker station very 
well because the louder stations were retarding the AGC. 
This blocking is common to AF DSP radios like a IC746 but I 
would have not expected it to occur on the K3. I have owned 
a IC7800 for 5 years and even though the lab tests show it 
to be not as good as the K3 I have never experienced 
blocking inside of the selected passband like I have seen on 
my K3.

I found if the DSP is set the same as the 400Hz crystal 
filter ,I have 8 pole, the blocking does not occur. But 
larger signals inside of the crystal filter BW makes copy 
hard.

Is there a way to fix this? Perhaps a setup value change or 
something. I purchased this radio to take on DXpeditions. At 
this point I not sure if I could reduce the BW using the DSP 
inside of the 400Hz filter without problems.

Thanks in advance,

Dave Anderson, K4SV
Tryon, NC
828 777-5088

www.K4SV.com
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