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K2: "Pop" when switching certain bands

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Jim KO5V

K2: "Pop" when switching certain bands

Good Afternoon,

Today I noticed a "pop" on the audio of my K2 when I changed in and out 15M, so I checked the switching on all bands:

When changing from 15M to 12M or 17M it is fairly loud. Changing from 12M or 17M to 15M causes a fainter "pop". A much more attenuated "pop" happens when changing from 14M to 10M, and also from 10M back to 14m.

Also, on 15M, when changing from VFO B to VFO A I hear a loud "pop", but it does not happen going from A to B.

The fainter "pops" might have always been there, but the ones on 15M are loud enough to cause the clip light on my DSP to turn red.

I wonder if it has something to do with diodes across relays, or the relays themselves.

Any more ideas? Thanks in advance.

73, Jim KO5V

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Don Wilhelm

Re: K2: "Pop" when switching certain bands

Jim,

Do you have 8R Hold turned on? If not, set it on.

Remove that external DSP speaker and see if you still have objectional pops.

Do you have the KDSP2 installed? On older K2s with the older KPA100
installed, you can experience some harmless "pops", especially if you
have the DSP NR turned on.

The number of relays which are switched during a band change varies
depending on which bands you are coming from and going to - so relay
clicking is normal.

You might want to check RF Board Q23 to be sure it is working. The
voltages during receive and transmit should be as shown in the DC
voltage tables.

73,
Don W3FPR

On 6/30/2019 4:55 PM, Jim KO5V wrote:

> Good Afternoon,
>
> Today I noticed a "pop" on the audio of my K2 when I changed in and out 15M, so I checked the switching on all bands:
>
> When changing from 15M to 12M or 17M it is fairly loud. Changing from 12M or 17M to 15M causes a fainter "pop". A much more attenuated "pop" happens when changing from 14M to 10M, and also from 10M back to 14m.
>
> Also, on 15M, when changing from VFO B to VFO A I hear a loud "pop", but it does not happen going from A to B.
>
> The fainter "pops" might have always been there, but the ones on 15M are loud enough to cause the clip light on my DSP to turn red.
>
> I wonder if it has something to do with diodes across relays, or the relays themselves.
>
> Any more ideas? Thanks in advance.
>
> 73, Jim KO5V
>
> ______________________________________________________________
> Elecraft mailing list
> Home: http://mailman.qth.net/mailman/listinfo/elecraft
> Help: http://mailman.qth.net/mmfaq.htm
> Post: mailto:[hidden email]
>
> This list hosted by: http://www.qsl.net
> Please help support this email list: http://www.qsl.net/donate.html
> Message delivered to [hidden email]
>

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Jim KO5V

Re: K2: "Pop" when switching certain bands

In reply to this post by Jim KO5V

Hi Don,

OK, the rig is S/N 7225. No KDSP2 is installed. I'm using an external CLRdsp box and speaker. The rig has been working very well; I've received many good signal reports. The DSP , AUX I/O, antenna and mic are all disconnected. I can hear this on the K2's internal speaker as well.

I accessed the menu, and set it to 8R Hold. Then, each time I access that menu, it shows 8R nor, so I'm not sure if the setting isn't "sticking", or that it just resets each time it is accessed (or maybe I don't know what I'm doing).

Q23 measures 0V, 0V, 7.9V (8V nominal), which is what the manual says.

These pops are not clicking relays. They are in the audio, and might have always been there. I started using VFO B on 15M to check 20MHz WWV, so I just noticed the issue. The loudest pop happens when switching from 15M VFO B to A (but not A to B). None of the other bands do this. It's also rather pronounced when switching into and out of the bands on each side of 15M.

Maybe it's just one of those "it just does that" situations, but it seems a bit strange to me that it is only on one band. I do hear a faint one when switching between 10M and 20M, but it's not at all obnoxious.

Thanks again. 73,

Jim KO5V

>Jim,
>
>Do you have 8R Hold turned on? If not, set it on.
>
>Remove that external DSP speaker and see if you still have objectional pops.
>
>Do you have the KDSP2 installed? On older K2s with the older KPA100
>installed, you can experience some harmless "pops", especially if you
>have the DSP NR turned on.
>
>The number of relays which are switched during a band change varies
>depending on which bands you are coming from and going to - so relay
>clicking is normal.
>
>You might want to check RF Board Q23 to be sure it is working. The
>voltages during receive and transmit should be as shown in the DC
>voltage tables.
>
>73,
>Don W3FPR
>
>
>On 6/30/2019 4:55 PM, Jim KO5V wrote:
>> Good Afternoon,
>>
>> Today I noticed a "pop" on the audio of my K2 when I changed in and out 15M, so I checked the switching on all bands:
>>
>> When changing from 15M to 12M or 17M it is fairly loud. Changing from 12M or 17M to 15M causes a fainter "pop". A much more attenuated "pop" happens when changing from 14M to 10M, and also from 10M back to 14m.
>>
>> Also, on 15M, when changing from VFO B to VFO A I hear a loud "pop", but it does not happen going from A to B.
>>
>> The fainter "pops" might have always been there, but the ones on 15M are loud enough to cause the clip light on my DSP to turn red.
>>
>> I wonder if it has something to do with diodes across relays, or the relays themselves.
>>
>> Any more ideas? Thanks in advance.
>>
>> 73, Jim KO5V

Don Wilhelm

Re: K2: "Pop" when switching certain bands

Jim,

On the setting of 8R HOLD, are you exiting the menu after making the
change? (tap MENU twice).

You may want to look at the RF board schematic sheet 3. All the
capacitors around U1 (The IO Controller) can be checked for proper
values (most are .001uF marked 102). Also check that they are all in the
proper holes (and not through an adjacent via hole).

How are you switching directly from 10m to 20m? With the BAND+/BAND-
buttons, you must cycle though 15 meters going between 20m and 10m, so I
am a bit confused by your statement. If you are using a software
application to switch, remove it and test from the K2 buttons.

73,
Don W3FPR

On 7/1/2019 1:04 PM, Jim KO5V wrote:

> Hi Don,
>
> OK, the rig is S/N 7225. No KDSP2 is installed. I'm using an external CLRdsp box and speaker. The rig has been working very well; I've received many good signal reports. The DSP , AUX I/O, antenna and mic are all disconnected. I can hear this on the K2's internal speaker as well.
>
> I accessed the menu, and set it to 8R Hold. Then, each time I access that menu, it shows 8R nor, so I'm not sure if the setting isn't "sticking", or that it just resets each time it is accessed (or maybe I don't know what I'm doing).
>
> Q23 measures 0V, 0V, 7.9V (8V nominal), which is what the manual says.
>
> These pops are not clicking relays. They are in the audio, and might have always been there. I started using VFO B on 15M to check 20MHz WWV, so I just noticed the issue. The loudest pop happens when switching from 15M VFO B to A (but not A to B). None of the other bands do this. It's also rather pronounced when switching into and out of the bands on each side of 15M.
>
> Maybe it's just one of those "it just does that" situations, but it seems a bit strange to me that it is only on one band. I do hear a faint one when switching between 10M and 20M, but it's not at all obnoxious.
>
> Thanks again. 73,
>
> Jim KO5V
>

Jim KO5V

Re: K2: "Pop" when switching certain bands

In reply to this post by Jim KO5V

Don,

I tap menu, then select t-r, then hold menu to move the cursors underneath the 0.00. I then tap Display and see 8r nor, then tap again to select 8r hold. Within a second or so, the display atomatically goes back to t-r with 0.00 underlined. I then tap menu twice to exit.

Please see my last email about the "10M"-20M. I meant 30M. I was evidently thinking 10Mhz...sorry.

I'll check the caps as you suggest.

Thanks again. 73,

Jim KO5V

>Jim,
>
>On the setting of 8R HOLD, are you exiting the menu after making the
>change? (tap MENU twice).
>
>You may want to look at the RF board schematic sheet 3. All the
>capacitors around U1 (The IO Controller) can be checked for proper
>values (most are .001uF marked 102). Also check that they are all in the
>proper holes (and not through an adjacent via hole).
>
>How are you switching directly from 10m to 20m? With the BAND+/BAND-
>buttons, you must cycle though 15 meters going between 20m and 10m, so I
>am a bit confused by your statement. If you are using a software
>application to switch, remove it and test from the K2 buttons.
>
>73,
>Don W3FPR