[Elecraft] Fw: Re: K2: "Pop" when switching certain bands

[Jim KO5V]

Don,

Setting each VFO to a frequency within the 15M band cured the "VFO B-A" pop. I checked the other bands, and found 20M "popping" when changing VFOs. One was set to 14.223, the other to 14.342. I found a pop as I tuned through ~14.348, so setting that VFO to a frequency lower that that, cured it. Does the rig effectively tune through the frequencies between the VFOs as it is switched, so if there are pops, it might see them?

I still hear pops that are louder than I like as I tune from 15M to 12M, and 17M. When going from each of those bands into 15, it is more of a click - like between 20M and 10M. I guess I can live with that.

Thanks again for your patience. and for sharing your experience.

73, Jim KO5V


-----Original Message-----
>From: Don Wilhelm <donwilh at embarqmail.com>
>Sent: Jul 3, 2019 4:49 PM
>To: Jim KO5V <ko5v at earthlink.net>, Elecraft List <elecraft at mailman.qth.net>
>Subject: Re: Fw: Re: K2: "Pop" when switching certain bands
>
>Jim,
>
>There is no relay action when changing from VFO A to B or the other way 
>around - the MCU just sends different data to the PLL and PLL Reference 
>Oscillator.
>
>However, 20 MHz may be on the lower limit of the available VFO tuning 
>range for 15 meters.
>Try tuning the VFO for both A and B back into the 15 meter band limits.
>
>73,
>Don W3FPR
>
>
>
>On 7/3/2019 3:57 PM, Jim KO5V wrote:
>> Hi again,
>>
>> I did as Don suggested, and checked the values of all of the capacitors around U1, and all of the band-switching relays. I also re-flowed all of their solder joints. With the bottom panels, top panel and the left-side panel off, the click in the audio was a lot better, and switching VFOs on 15M was quiet. However, after I put it all back together, it's all returned. I looked the the S-meter, and with the RF gain set fully cw, I see the following brief readings that accompany the clicks and pops in the speaker:
>>
>> 15M, VFO A to VFO B: S1;
>> *15M, VFO B to VFO A: S9;
>>
>> 15M-17M: S1;
>> 17M-15M: click, no reading;
>>
>> *15M-12M: S5;
>> 12M-15M: click, no reading;
>>
>> 20M-30M: click, no reading;
>> 30M-20M: click, no reading.
>>
>> The other bands/VFOs switch quietly.
>>
>> Otherwise, the radio seems to work just fine, and has been performing well. I recently set 15M VFO B to 20MHz WWV, and that's when I noticed this. I wonder if I should just forget about it, except the S5 and S9 pops just don't give me a good feeling.
>>
>> How does the radio switch between VFO A and VFO B? I assume it's done in the firmware, but is some relay (or a band-specific relay) involved?
>>
>>
>