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Its not over yet, I've gone back to basic K2 troubleshooting and find i have what seems a massive loss through the variable Crystal filter ?

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Clifford Hynds

Its not over yet, I've gone back to basic K2 troubleshooting and find i have what seems a massive loss through the variable Crystal filter ?

Still having issues with my K2,

I did align the filters using the Spectrogram software so I believe they
are ok

Well I decided to start from scratch and started RX troubleshooting/signal
tracing before I go back to TX side want to make sure the RX is 100% and
while the stages up to the input of the crystal filter look ok the output
compared to the manual is extremely low.

I ended up using the RF probe supplied in the kit so all is known.

Also removed the SSB board and fitted the corresponding jumpers at W2 and
W3 and C167

Here is what i am seeing with a 0.14Vrms input to the antenna I used
10.1Mhz but I tried other bands with similar results.

All voltages up to the input of the variable crystal filter look normal.

Case or collector of Q22 = 2.3Vrms

At W2 = ~ 2Vrms

cathode D30 =0.89Vrms

cathode D31 =0.95Vrms

cathode D32 =0.757Vrms

cathode D33 =0.767Vrms

cathode D34 =0.735Vrms

W3 = 0.080Vrms the K2 book on Page 11 says it should be about 0.34Vrms , I
am way low compared to that.

I suspect either D34 or T7 ?

Also I don't appear to be able to saturate IF amp it says I should read
approx 0.15Vrms at Pin 8 of U12

Am I on the right track.

Thanks again,
Cliff VK2CCJ
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Don Wilhelm-4

Re: Its not over yet, I've gone back to basic K2 troubleshooting and find i have what seems a massive loss through the variable Crystal filter ?

Cliff,

When looking at the RF voltage after the IF filter, tune the K2 slowly
while looking for the peak RF voltage at U12 pin 4.
You will not be able to see the IF amplifier saturation with diodes D40
and D41 in place - that information is prior to the introduction of
those diodes.

T7 should be with the green winding closest to the crystal filter, the
red winding adjacent to pins 4 and 5 of U12.
Turn off the AGC (press PRE and REV buttons together) and see if the
audio level comes up.
You should have more RF voltage at U12 pin 8 than you do at U12 pin 4.

73,
Don W3FPR

On 1/29/2013 8:21 PM, Clifford Hynds wrote:

> Still having issues with my K2,
>
> I did align the filters using the Spectrogram software so I believe they
> are ok
>
> Well I decided to start from scratch and started RX troubleshooting/signal
> tracing before I go back to TX side want to make sure the RX is 100% and
> while the stages up to the input of the crystal filter look ok the output
> compared to the manual is extremely low.
>
> I ended up using the RF probe supplied in the kit so all is known.
>
> Also removed the SSB board and fitted the corresponding jumpers at W2 and
> W3 and C167
>
> Here is what i am seeing with a 0.14Vrms input to the antenna I used
> 10.1Mhz but I tried other bands with similar results.
>
> All voltages up to the input of the variable crystal filter look normal.
>
> Case or collector of Q22 = 2.3Vrms
>
> At W2 = ~ 2Vrms
>
> cathode D30 =0.89Vrms
>
> cathode D31 =0.95Vrms
>
> cathode D32 =0.757Vrms
>
> cathode D33 =0.767Vrms
>
> cathode D34 =0.735Vrms
>
> W3 = 0.080Vrms the K2 book on Page 11 says it should be about 0.34Vrms , I
> am way low compared to that.
>
> I suspect either D34 or T7 ?
>
> Also I don't appear to be able to saturate IF amp it says I should read
> approx 0.15Vrms at Pin 8 of U12
>
> Am I on the right track.
>
> Thanks again,
> Cliff VK2CCJ
> ______________________________________________________________
> 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
>

______________________________________________________________
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Clifford Hynds

Re: Its not over yet, I've gone back to basic K2 troubleshooting and find i have what seems a massive loss through the variable Crystal filter ?

Ok Don,

T7 is right way round, continuity seems good

Audio does increase when AGC turned off

Unfortunately U12 output at pin 8 is much lower than pin4

with 0.14Vrms Ant input and RFgain at minimum

0.365Vrms at Pin4

0.025vRMS at Pin 8 changing to 0.151 when RF gain turned fully up.

U12 DC Voltages seem ok.

1 7.74
2 7.74
3 0
4 0
5 4
6 2.467
7 0
8 7.73

73
Cliff VK2CCJ

On Wed, Jan 30, 2013 at 1:27 PM, Don Wilhelm <[hidden email]> wrote:

> Cliff,
>
> When looking at the RF voltage after the IF filter, tune the K2 slowly
> while looking for the peak RF voltage at U12 pin 4.
> You will not be able to see the IF amplifier saturation with diodes D40
> and D41 in place - that information is prior to the introduction of those
> diodes.
>
> T7 should be with the green winding closest to the crystal filter, the red
> winding adjacent to pins 4 and 5 of U12.
> Turn off the AGC (press PRE and REV buttons together) and see if the audio
> level comes up.
> You should have more RF voltage at U12 pin 8 than you do at U12 pin 4.
>
> 73,
> Don W3FPR
>
>
> On 1/29/2013 8:21 PM, Clifford Hynds wrote:
>
>> Still having issues with my K2,
>>
>> I did align the filters using the Spectrogram software so I believe they
>> are ok
>>
>> Well I decided to start from scratch and started RX troubleshooting/signal
>> tracing before I go back to TX side want to make sure the RX is 100% and
>> while the stages up to the input of the crystal filter look ok the output
>> compared to the manual is extremely low.
>>
>> I ended up using the RF probe supplied in the kit so all is known.
>>
>> Also removed the SSB board and fitted the corresponding jumpers at W2 and
>> W3 and C167
>>
>> Here is what i am seeing with a 0.14Vrms input to the antenna I used
>> 10.1Mhz but I tried other bands with similar results.
>>
>> All voltages up to the input of the variable crystal filter look normal.
>>
>> Case or collector of Q22 = 2.3Vrms
>>
>> At W2 = ~ 2Vrms
>>
>> cathode D30 =0.89Vrms
>>
>> cathode D31 =0.95Vrms
>>
>> cathode D32 =0.757Vrms
>>
>> cathode D33 =0.767Vrms
>>
>> cathode D34 =0.735Vrms
>>
>> W3 = 0.080Vrms the K2 book on Page 11 says it should be about 0.34Vrms ,
>> I
>> am way low compared to that.
>>
>> I suspect either D34 or T7 ?
>>
>> Also I don't appear to be able to saturate IF amp it says I should read
>> approx 0.15Vrms at Pin 8 of U12
>>
>> Am I on the right track.
>>
>> Thanks again,
>> Cliff VK2CCJ
>> ______________________________**______________________________**__
>> Elecraft mailing list
>> Home: http://mailman.qth.net/**mailman/listinfo/elecraft<http://mailman.qth.net/mailman/listinfo/elecraft>
>> Help: http://mailman.qth.net/mmfaq.**htm<http://mailman.qth.net/mmfaq.htm>
>> Post: mailto:[hidden email].**net <[hidden email]>
>>
>> This list hosted by: http://www.qsl.net
>> Please help support this email list: http://www.qsl.net/donate.html
>>
>>
>