[Elecraft] K3 and QSK

[Chester Alderman]

Joe,

I think you are exactly correct! It does happen with 'key up' or between words and it seems to last for only a few seconds at the most. But it is very objectionable to listen to for many hours during contest.

Thanks for your observation and input!

73,
Tom - W4BQF


-----Original Message-----
From: Elecraft [mailto:elecraft-bounces at mailman.qth.net] On Behalf Of Joe Subich, W4TV
Sent: Thursday, December 4, 2014 10:00 AM
To: elecraft at mailman.qth.net
Subject: Re: [Elecraft] K3 and QSK


> The amplitude of this click depends on the amount of noise or signals 
> in the 'channel'. When listening to rx noise with no antenna, there's 
> no click. The worst case is a big pileup.

It would appear that the K3 is momentarily running at full gain when returning from transmit, the "click" being full gain until the AGC can
react to signal levels 'in the channel'.   That supposition can only be
confirmed by Lyle or Wayne but you might be able to moderate the click by turning off AGC and riding the RF gain.

73,

    ... Joe, W4TV


On 2014-12-04 9:05 AM, Vic Rosenthal wrote:
> Tommy,
>
> I have 8 pole filters for 400, 1000 and 2800 Hz. I am almost always using the 400 on CW. I use QRQ mode whenever possible. I found various sources of clicks including bias switching in my amplifier, and a switched power source for my Pixel Loop. I removed everything to isolate the problem. All tests were done in TX TEST mode, no RF generated.
>
> The most bothersome K3 generated noise is a click when returning to receive state. You hear it in full or semi- QSK mode when returning to receive. The amplitude of this click depends on the amount of noise or signals in the 'channel'. When listening to rx noise with no antenna, there's no click. The worst case is a big pileup. There is also a noise that is hard to describe, sort of a fuzziness around the sidetone. That also depends on the amount of signal and noise in the background.
>
> Turning down either the audio or RF gain helps with both artifacts, but makes the output lower than desirable.
>
> I talked to Wayne and Lyle a long time ago about possible ways to ameliorate these noises and they had some ideas, but I haven't heard anything recently.
>
> Vic 4X6GP/K2VCO
>
>> On Dec 4, 2014, at 3:22 PM, Chester Alderman <aldermant at windstream.net> wrote:
>>
>> Hi Vic,
>>
>> With interest, I read your emails about the K3 QSK and the noise it produced and I have a question for you. I’ve had my K3 for about three years and I purchased it with a full complement of CW filters for both receivers, including the 8-pole 250 hz filter. I normally run my radios in full QSK, but of course, depending on sending speed, running the K3 in full QSK means you lose too many other good features.
>>
>>
>> I never really noticed the noise generated while in full QSK until recently, and it is quite bad! About a year ago I changed my 8-pole 250 hz filter to the 5 pole 250 hz filter and actually I think that is when I started noticing how bad the pumping and generated noise from my K3 sounded. Of course I run AGC-Fast, with no preamp (unless on 10m and then only seldom have the preamp turned on).
>>
>>
>> My question to you is do you have the 250 hz filter installed in the main Rx and if so, is it the 8-pole or the 5-pole? I think right after Christmas I am going to re-install my 8-pole filter just to see if that has any bearing on the awful QSK noise.
>>
>> Also, have you had any response from Elecraft on this issue?
>>
>>
>> Thanks for any comment Vic and 73,
>>
>> Tom – W4BQF
>>
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