[Elecraft] K3 and QSK

[Vic Rosenthal 4X6GP/K2VCO]

No, AGC on/off has no effect.

On 4 Dec 2014 17:00, Joe Subich, W4TV wrote:
>
>> 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


-- 
73,
Vic, 4X6GP/K2VCO
Rehovot, Israel
http://www.qsl.net/k2vco/