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Fw: Re: K2: "Pop" when switching certain bands

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Jim KO5V

Fw: Re: K2: "Pop" when switching certain bands

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?

Has anyone else with a K2 noticed something similar? Should I be looking somewhere else, or just move on?

Thanks, and sorry to keep obsessing about this.

73, Jim KO5V

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Don Wilhelm

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?
>
>

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Jim KO5V

Re: Fw: Re: K2: "Pop" when switching certain bands

In reply to this post by 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 <[hidden email]>
>Sent: Jul 3, 2019 4:49 PM
>To: Jim KO5V <[hidden email]>, Elecraft List <[hidden email]>
>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?
>>
>>
>

Don Wilhelm

Re: Fw: Re: K2: "Pop" when switching certain bands

Jim,

You might want to check the PLL Reference Oscillator Range on that K2 -
sometimes called the "R30 voltage".

Don W3FPR

On 7/3/2019 5:24 PM, Jim KO5V wrote:

> 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 <[hidden email]>
>> Sent: Jul 3, 2019 4:49 PM
>> To: Jim KO5V <[hidden email]>, Elecraft List <[hidden email]>
>> 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.
>>