[Elecraft] Noisy K-3 Receiver

Jim Harris w0em at q.com
Wed Dec 16 22:33:20 EST 2009


Dick,

I've had the same experience as you describe.  You will get some explanations here on the reflector that sort of make sense so I will not try to repeat them.  What it comes down to for me is there is less usable S meter range and amplified background noise to contend with.  A great receiver but having to listen to that background noise is disquieting.  I think the noise/S meter relationship needs a solid review from engineering aimed at putting a bit of a knee at the bottom of the scale and in the process dropping the apparent noise level.  A supersensitive receiver is great but when all it's doing is digging out noise it's of little value.  I agree NR and related controls help a bit on the noise but it doesn't address the underlying situation.

Many of us over-the-hill folks have a sensitivity to noise that younger people don't have so it may be hard for them to understand and appreciate our concern.

Have a good day and 73.

Jim, W0EM


Date: Tue, 15 Dec 2009 23:44:26 EST
From: RLVZ at aol.com
Subject: [Elecraft] Noisy K-3 Receiver
To: elecraft at mailman.qth.net
Message-ID: <be9.65ac7dd1.3859bfaa at aol.com>
Content-Type: text/plain; charset="US-ASCII"
 
Hi Guys,
 
I'd appreciate your thoughts as to why my K-3 receiver is so noisy.  I'd 
really like to make this radio perform.  The radio is Serial #603F (factory 
model) running 1.2.10.27.  I purchased the unit from the original owner a 
couple of months ago so I don't know if it's always been this noisy but I do 
know it was the same before I  recently updated software to 1.2.10.27.   The 
radio is in immaculate condition and was never used mobile or bounced around.  
(it's a beautiful radio that looks like new!)
 
I say the receiver is noisy based upon listening to dozens of different 
signals on: 40/20/15 m. and by doing numerous A/B comparison tests.  The 
comparison tests were done with the K-3 Pre-Amp turned Off.  (and tried with ATT 
on and off but mostly on to reduce noise).  
 
Radio 1: Yaesu FT-1000-MP w/AF Mod.  A signal is peaking S-8 and with the 
no signal noise level is averaging S-1.  Therefore, the signal is peaking 
aprx. 7 s-units above the noise based upon the MP s-meter and the signal sounds 
loud and is way above the noise level.  Now I switch to the K-3:
 
Radio 2: K-3 tuned to the same signal with PreAmp Off and is peaking S-7 
but the no signal noise level is noisy S-4 to S-5.  Therefore, the signal is 
peaking only about 2 or 3 s-units above the noise level based upon the K-3 
s-meter.  The result is that the MP has aprx. a 4 s-unit  S/N ratio advantage. 
 
 
Thoughts: I realize that all s-meters read differently and the fact that 
the MP s-meter shows a 4 s-unit stronger signal above the noise level  doesn't 
mean alot.  But the fact is that the signal on the MP sounds MUCH louder 
with alot more headroom above the noise level.  The K-3 receiver sounds so 
noisy even with the S-7 signal that it isn't enjoyable listening to and that's 
why I ran the comparisons because I couldn't stand all the noise.  Switching 
on the K-3's NR, ATT, and/or adjusting the RF Gain does help some but the 
signal still sounds noisy compared to the MP.  
 
Based upon "Reviews" of the K-3 I believe that I must have an unusual "K-3 
noisy receiver" problem.
 
I'd sure appreciate your ideas on how I can get a better S/N ratio on my 
K-3.       
 
Thanks!
 
73,
Dick- K9OM
 
 		 	   		  


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