[Elecraft] [K3] RE: K3 S-Meter and Noise

Sun Oct 4 18:55:06 EDT 2009

Don,

I did not say nor hopefully imply that my "procedure" was intended to be scientific.  I was simply doing a layman's side-by-side comparison.  Obviously, my K3 has a higher noise level than my other four radio's and it is represented on the S-meter.  QSO's that are something like S7 and above are a real problem as during pauses by the person on the other side as the AGC drops I'm hit with this rush of noise as the S-meter settles around S2+.  I don't hear this on my other radio's as the noise level is usually settles closer to S0.  After 20-30 minutes it becomes mostly unbearable.  Maybe this is one of the reasons so many people complain about K3 audio.

Thank you for the reminder about the MDS procedure in the XG1 manual.  I'll work on that in the next day or so as I get a chance.

One thing most interesting about this whole discussion on the email forum is that no one has said what I am experiencing is normal for a typical K3.  I've been in communication with support and Wayne and none have said it's normal.  I've had comments from I don't understand what I'm talking about to in-depth discussions on noise but no one has said what I'm experiencing is normal and it's not a problem.  

Wayne has offered a beta software with a revised RF gain procedure that may be of some benefit.  I'm going to ask him to send it and see how it works.

Thank you for your reply.  

Have a good day and 73.

Jim, W0EM

Date: Sat, 3 Oct 2009 20:50:36 -0700
From: ml-user+39068-1894282159 at n2.nabble.com
To: w0em at q.com
Subject: Re:  K3 S-Meter and Noise

Jim,

I know perception is 99% of reality, but your measurement technique is 

not entirely valid.

The proper way to make the determination of sensitivity is to measure 

the MDS of each of the receivers.

Use your XG1 signal generator to determine the MDS of each reciever 

using the technique outlined in the XG1 manual.

A more sensitive receiver will create more "antenna noise" than one that 

is less sensitive.  Say that the K3 can hear a -138 dBm signal, and the 

atmospheric noise is -136 dBm, then the K3 will hear all signals on that 

band that are greater than that -136 dBm noise level.  If the MDS of the 

other receivers is at -132 dBm, they will not be able to hear the 

atmospheric noise, and will also not be able to hear a signal of -133 

dBm either.

A receiver that hears more 'antenna noise' is usually the more sensitive 

one.

The noise floor - the noise level with the antenna disconnected - is the 

limit where the receiver will mask weak signals.  OTOH, atmospheric 

noise (antenna noise) will mask signals on all receivers.

73,

Don W3FPR

Jim HaRRIS wrote:

> Tom,

>

> I have three radio's in my shack besides the K3.  I've checked their

> S-meters with the recommended XG1 and all have comparable readings.  All

> four are equally quiet without an antenna connected and with a dummy load

> connected.  When connected to an antenna the K3 has about 2 S units more

> noise indicated than the other radios connected to the same antenna (A/B

> switch) and the noise level sounds about that much louder.  All volume

> controls are at about 9 o'clock.  This applies to most bands.  Strangely,

> WARC bands seem to be mostly excepted.

>

> This afternoon I took the my K3, K2 and FT-857D mobile using a 54" Li'l

> Tarheel II screwdriver antenna tuned to 20 meters.  I operated the K3 & K2

> from a SLA battery with the van turned off.  I was in a park with nothing

> electrical for at least a half mile.  Volume was again set at 9 0'clock on

> all three.  The K3 have a steady S1 with peaks to S3.  The other radios had

> S0 with no peaks.  Volumes sounded appropriate for indicated S-meter

> reading.  

>

> I've almost completely disassembled the radio and reassembled it and done

> the EE INIT reset with no change.

>

> It's apparent this K3 is more sensitive to antenna noise than the other four

> radio's which are all about equal.  This leads me to believe this particular

> radio is going to bury weak signals in noise making them harder to dig out

> than the other radios.

>

> I've exchanged several emails with support and next week I'm supposed to

> talk with someone higher up at Aptos.  I'm trying to be patient with this

> but it has been over a month since I placed the initial order.  During

> assembly I had to replace the DSP board for an unrelated problem.  If the

> radio has to go back to Aptos it will be close to two months since ordering

> before I have a fully functional radio.

>

> Have a good day and 73,

>

> Jim, W0EM

>   

>
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