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K2 Alignment and Test, Part II issues

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Don Schroder

K2 Alignment and Test, Part II issues

Hi folks,

Got to the subject location on my K2 kit #7818, and am having some difficulties with the tests. My frequency counter, when touched to the left side of trimmer capacitor C22, reads 3999.98 on the LCD. This makes me believe there is no problem with the frequency counter probe that I assembled.

On page 63, under *4 MHz Oscillator Calibration, I selected CAL FCTR, and the LCD displays a rapidly changing frequency between 185.~ to 188.~. It does not show a frequency of 12090 kHz suggested by the manual. This tells me I have a problem with the PLL Reference Oscillator (since the frequency counter probe appeared to be ok). I then decided to check voltages, and discovered that I am missing some +5v signals from U4 and U5.

Any suggestions on where to look next? I’d like to trace the 5v signals, but I don’t see how to do that using the schematics. I did measure voltages on the 8 pins of the Thermistor Board, they were all 0 volts! That didn’t seem right, either.

Appreciate any suggestions! Thanks!
Don, KE0PVQ

Sent from Mail<https://go.microsoft.com/fwlink/?LinkId=550986> for Windows 10

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Don Wilhelm

Re: K2 Alignment and Test, Part II issues

Don,

First check the DC voltage at RF Board U6 pin 5 - it should be 4 volts
(or 1/2 the 8 volt regulator output voltage). If it is not correct, you
have a problem with the thermistor board - most likely a solder bridge.

You should have 8 volts at the thermistor board pin 8. If that is not
correct, look carefully for solder bridges. That 8 volts comes directly
from the 8 volt regulator voltage rail.

It does sound like you have a problem with the PLL Reference Oscillator,
but your voltage measurements on the thermistor board pins should be
investigated first before drawing any other conclusions.

Make sure you have good results with the PLL range tests just after that.

The exact frequency of the 4 MHz Oscillator is not critical at this
point - for now it only substantiates that the oscillator is working.
If you put a probe on C22, it will pull the frequency. If your
frequency counter is sufficiently accurate, wait until you have a good
frequency at TP1, and then measure the frequency with both the counter
and the internal counter probe using CAL FCTR. Adjust C22 so CAL FCTR
frequency is the same as your external counter.

I do not know the accuracy of your counter, but mine is accurate to 10
exp-9 and I can set C22 with it for good K2 Dial Calibration. There are
other methods for setting C22 that do not depend on the accuracy of your
frequency counter. When you can receive WWV at 10 or better 15 MHz,
look at my website www.w3fpr.com article on K2 Dial Calibration to
accurately set C22 and achieve good K2 dial calibration.

73,
Don W3FPR

On 9/26/2018 8:14 PM, Don Schroder wrote:

> Hi folks,
>
> Got to the subject location on my K2 kit #7818, and am having some difficulties with the tests. My frequency counter, when touched to the left side of trimmer capacitor C22, reads 3999.98 on the LCD. This makes me believe there is no problem with the frequency counter probe that I assembled.
>
> On page 63, under *4 MHz Oscillator Calibration, I selected CAL FCTR, and the LCD displays a rapidly changing frequency between 185.~ to 188.~. It does not show a frequency of 12090 kHz suggested by the manual. This tells me I have a problem with the PLL Reference Oscillator (since the frequency counter probe appeared to be ok). I then decided to check voltages, and discovered that I am missing some +5v signals from U4 and U5.
>
> Any suggestions on where to look next? I’d like to trace the 5v signals, but I don’t see how to do that using the schematics. I did measure voltages on the 8 pins of the Thermistor Board, they were all 0 volts! That didn’t seem right, either.
>
> Appreciate any suggestions! Thanks!
> Don, KE0PVQ
>
> Sent from Mail<https://go.microsoft.com/fwlink/?LinkId=550986> for Windows 10
>
> ______________________________________________________________
> 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]
>

______________________________________________________________
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]

Don Wilhelm

Re: K2 Alignment and Test, Part II issues

In reply to this post by Don Schroder

Don,

First check the DC voltage at RF Board U6 pin 5 - it should be 4 volts
(or 1/2 the 8 volt regulator output voltage). If it is not correct, you
have a problem with the thermistor board - most likely a solder bridge.

You should have 8 volts at the thermistor board pin 8. If that is not
correct, look carefully for solder bridges. That 8 volts comes directly
from the 8 volt regulator voltage rail.

It does sound like you have a problem with the PLL Reference Oscillator,
but your voltage measurements on the thermistor board pins should be
investigated first before drawing any other conclusions.

Make sure you have good results with the PLL range tests just after that.

The exact frequency of the 4 MHz Oscillator is not critical at this
point - for now it only substantiates that the oscillator is working. If
you put a probe on C22, it will pull the frequency. If your frequency
counter is sufficiently accurate, wait until you have a good frequency
at TP1, and then measure the frequency with both the counter and the
internal counter probe using CAL FCTR. Adjust C22 so CAL FCTR frequency
is the same as your external counter.

I do not know the accuracy of your counter, but mine is accurate to 10
exp-9 and I can set C22 with it for good K2 Dial Calibration. There are
other methods for setting C22 that do not depend on the accuracy of your
frequency counter. When you can receive WWV at 10 or better 15 MHz,
look at my website www.w3fpr.com article on K2 Dial Calibration to
accurately set C22 and achieve good K2 dial calibration.

73,
Don W3FPR

On 9/26/2018 8:14 PM, Don Schroder wrote:

Don Schroder

Re: K2 Alignment and Test, Part II issues

Don,
Board U6 pin 5
Thank you for the suggestions! The DC voltage at RF Board U6 pin 5 is 0 volts. In fact, all pins of U6, except pin 6, are 0 volts. Pin 6 is less than 1 volt.

I saw a bridge between C96 and RFC10, the schematic shows these two components connecting together, so that should be ok. I’m still looking for bridges.

Could you elaborate a little on the ^voltage rail*? How do I identify the rail on a schematic, or can I? Which component is the 8 volt regulator? I feel I should know the answers to these questions, I must be having a senior moment. Your help and advice is much appreciarted!

Thanks!
Don, KE0PVQ

Sent from Mail<https://go.microsoft.com/fwlink/?LinkId=550986> for Windows 10

From: Don Wilhelm<mailto:[hidden email]>
Sent: Thursday, September 27, 2018 11:01 AM
To: Don Schroder<mailto:[hidden email]>; [hidden email]<mailto:[hidden email]>
Subject: Re: [Elecraft] K2 Alignment and Test, Part II issues

Don,

First check the DC voltage at RF Board U6 pin 5 - it should be 4 volts
(or 1/2 the 8 volt regulator output voltage). If it is not correct, you
have a problem with the thermistor board - most likely a solder bridge.

You should have 8 volts at the thermistor board pin 8. If that is not
correct, look carefully for solder bridges. That 8 volts comes directly
from the 8 volt regulator voltage rail.

It does sound like you have a problem with the PLL Reference Oscillator,
but your voltage measurements on the thermistor board pins should be
investigated first before drawing any other conclusions.

Make sure you have good results with the PLL range tests just after that.

The exact frequency of the 4 MHz Oscillator is not critical at this
point - for now it only substantiates that the oscillator is working. If
you put a probe on C22, it will pull the frequency. If your frequency
counter is sufficiently accurate, wait until you have a good frequency
at TP1, and then measure the frequency with both the counter and the
internal counter probe using CAL FCTR. Adjust C22 so CAL FCTR frequency
is the same as your external counter.

I do not know the accuracy of your counter, but mine is accurate to 10
exp-9 and I can set C22 with it for good K2 Dial Calibration. There are
other methods for setting C22 that do not depend on the accuracy of your
frequency counter. When you can receive WWV at 10 or better 15 MHz,
look at my website www.w3fpr.com article on K2 Dial Calibration to
accurately set C22 and achieve good K2 dial calibration.

73,
Don W3FPR

On 9/26/2018 8:14 PM, Don Schroder wrote:

Don Wilhelm

Re: K2 Alignment and Test, Part II issues

Don,

You apparently have a problem with the thermistor board - or the 8 volts
to it.
A "voltage rail" are those PC traces that carry voltage to various parts
of the circuit.
In the K2, there is one for 12 volts, another for 8 volts and another
for 5 volts.
On the schematic they are labeled "12V", "8A" and "5V" respectively.
The main 8 volt and 5 volt regulators are on the Control Board. You will
find an "5B" voltage rail at the output of U8 on the RF Board and the
"8B" voltage is sourced at the output side of RFC16.
If you do not have 8 volts at the thermistor board pin 8, then
investigate the stripping and tinning of the RFC16 leads.
Once you have 8 volts at the thermistor board (RP3 position) pin 8, then
recheck the voltage at U6 pin 5 - it should be quite close to 4 volts.

73,
Don W3FPR

On 9/27/2018 1:43 PM, Don Schroder wrote:

>
> Don,
>
> Board U6 pin 5
>
> Thank you for the suggestions! The DC voltage at RF Board U6 pin 5 is
> 0 volts. In fact, all pins of U6, except pin 6, are 0 volts. Pin 6 is
> less than 1 volt.
>
> I saw a bridge between C96 and RFC10, the schematic shows these two
> components connecting together, so that should be ok. I’m still
> looking for bridges.
>
> Could you elaborate a little on the ^voltage rail*? How do I identify
> the rail on a schematic, or can I? Which component is the 8 volt
> regulator? I feel I should know the answers to these questions, I must
> be having a senior moment. Your help and advice is much appreciarted!
>
> Thanks!
>
> Don, KE0PVQ
>
> Sent from Mail <https://go.microsoft.com/fwlink/?LinkId=550986> for
> Windows 10
>
> *From: *Don Wilhelm <mailto:[hidden email]>
> *Sent: *Thursday, September 27, 2018 11:01 AM
> *To: *Don Schroder <mailto:[hidden email]>;
> [hidden email] <mailto:[hidden email]>
> *Subject: *Re: [Elecraft] K2 Alignment and Test, Part II issues
>
> Don,
>
> First check the DC voltage at RF Board U6 pin 5 - it should be 4 volts
>
> (or 1/2 the 8 volt regulator output voltage). If it is not correct, you
>
> have a problem with the thermistor board - most likely a solder bridge.
>
> You should have 8 volts at the thermistor board pin 8. If that is not
>
> correct, look carefully for solder bridges. That 8 volts comes directly
>
> from the 8 volt regulator voltage rail.
>
> It does sound like you have a problem with the PLL Reference Oscillator,
>
> but your voltage measurements on the thermistor board pins should be
>
> investigated first before drawing any other conclusions.
>
> Make sure you have good results with the PLL range tests just after that.
>
> The exact frequency of the 4 MHz Oscillator is not critical at this
>
> point - for now it only substantiates that the oscillator is working. If
>
> you put a probe on C22, it will pull the frequency. If your frequency
>
> counter is sufficiently accurate, wait until you have a good frequency
>
> at TP1, and then measure the frequency with both the counter and the
>
> internal counter probe using CAL FCTR. Adjust C22 so CAL FCTR frequency
>
> is the same as your external counter.
>
> I do not know the accuracy of your counter, but mine is accurate to 10
>
> exp-9 and I can set C22 with it for good K2 Dial Calibration. There are
>
> other methods for setting C22 that do not depend on the accuracy of your
>
> frequency counter. When you can receive WWV at 10 or better 15 MHz,
>
> look at my website www.w3fpr.com article on K2 Dial Calibration to
>
> accurately set C22 and achieve good K2 dial calibration.
>
> 73,
>
> Don W3FPR
>
> On 9/26/2018 8:14 PM, Don Schroder wrote:
>
> > Hi folks,
>
> >
>
> > Got to the subject location on my K2 kit #7818, and am having some
> difficulties with the tests. My frequency counter, when touched to the
> left side of trimmer capacitor C22, reads 3999.98 on the LCD. This
> makes me believe there is no problem with the frequency counter probe
> that I assembled.
>
> >
>
> > On page 63, under *4 MHz Oscillator Calibration, I selected CAL
> FCTR, and the LCD displays a rapidly changing frequency between 185.~
> to 188.~. It does not show a frequency of 12090 kHz suggested by the
> manual. This tells me I have a problem with the PLL Reference
> Oscillator (since the frequency counter probe appeared to be ok). I
> then decided to check voltages, and discovered that I am missing some
> +5v signals from U4 and U5.
>
> >
>
> > Any suggestions on where to look next? I’d like to trace the 5v
> signals, but I don’t see how to do that using the schematics. I did
> measure voltages on the 8 pins of the Thermistor Board, they were all
> 0 volts! That didn’t seem right, either.
>
> >
>
> > Appreciate any suggestions! Thanks!
>
> > Don, KE0PVQ
>
> >
>
> > Sent from Mail<https://go.microsoft.com/fwlink/?LinkId=550986> for
> Windows 10
>
> >
>
> > ______________________________________________________________
>
> > 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]
>
> >
>

Don Schroder

Re: K2 Alignment and Test, Part II issues

Don,

Thank you for the excellent advice! I went to the bottom of the board and checked the resistance between the ends of RFC16. It was infinite, so I rewound RFC16 and ensured the leads were cleaned good. After reinstalling, I now have 4.~ votes at U6 pin 5, and 8.~ at pin 8. Pin 8 of the Thermistor Board has 8.~ volts, too.

Now, when I select CAL FCTR and enable the frequency counter, the counter shows 00000.00. I believe this tells me there is a problem with the PLL Reference Oscillator. I will continue to look at those components. Any other suggestions?

Thanks!
Don, KE0PVQ

Sent from Mail<https://go.microsoft.com/fwlink/?LinkId=550986> for Windows 10

From: Don Wilhelm<mailto:[hidden email]>
Sent: Thursday, September 27, 2018 1:34 PM
To: Don Schroder<mailto:[hidden email]>; [hidden email]<mailto:[hidden email]>
Subject: Re: [Elecraft] K2 Alignment and Test, Part II issues

Don,

You apparently have a problem with the thermistor board - or the 8 volts
to it.
A "voltage rail" are those PC traces that carry voltage to various parts
of the circuit.
In the K2, there is one for 12 volts, another for 8 volts and another
for 5 volts.
On the schematic they are labeled "12V", "8A" and "5V" respectively.
The main 8 volt and 5 volt regulators are on the Control Board. You will
find an "5B" voltage rail at the output of U8 on the RF Board and the
"8B" voltage is sourced at the output side of RFC16.
If you do not have 8 volts at the thermistor board pin 8, then
investigate the stripping and tinning of the RFC16 leads.
Once you have 8 volts at the thermistor board (RP3 position) pin 8, then
recheck the voltage at U6 pin 5 - it should be quite close to 4 volts.

73,
Don W3FPR

On 9/27/2018 1:43 PM, Don Schroder wrote:

Don Wilhelm

Re: K2 Alignment and Test, Part II issues

Don,

While in CAL FCTR, try the probe in TP3 and TP1 and TP2. If you have a
zero reading in all 3 places, you most likely have a bad probe.
Yes you might have a PLL problem, but that is not certain yet. One quick
check is to measure the resistance from the source of Q19 to ground. If
it is high or infinite, check the leads of RFC14 like you did for
RFC16. The normal resistance is a bit more than 270 ohms.

73,
Don W3FPR

On 9/27/2018 4:41 PM, Don Schroder wrote:

>
> Don,
>
> Thank you for the excellent advice! I went to the bottom of the board
> and checked the resistance between the ends of RFC16. It was infinite,
> so I rewound RFC16 and ensured the leads were cleaned good. After
> reinstalling, I now have 4.~ votes at U6 pin 5, and 8.~ at pin 8. Pin
> 8 of the Thermistor Board has 8.~ volts, too.
>
> Now, when I select CAL FCTR and enable the frequency counter, the
> counter shows 00000.00. I believe this tells me there is a problem
> with the PLL Reference Oscillator. I will continue to look at those
> components. Any other suggestions?
>
> Thanks!
>
> Don, KE0PVQ
>
> Sent from Mail <https://go.microsoft.com/fwlink/?LinkId=550986> for
> Windows 10
>
> *From: *Don Wilhelm <mailto:[hidden email]>
> *Sent: *Thursday, September 27, 2018 1:34 PM
> *To: *Don Schroder <mailto:[hidden email]>;
> [hidden email] <mailto:[hidden email]>
> *Subject: *Re: [Elecraft] K2 Alignment and Test, Part II issues
>
> Don,
>
> You apparently have a problem with the thermistor board - or the 8 volts
>
> to it.
>
> A "voltage rail" are those PC traces that carry voltage to various parts
>
> of the circuit.
>
> In the K2, there is one for 12 volts, another for 8 volts and another
>
> for 5 volts.
>
> On the schematic they are labeled "12V", "8A" and "5V" respectively.
>
> The main 8 volt and 5 volt regulators are on the Control Board. You will
>
> find an "5B" voltage rail at the output of U8 on the RF Board and the
>
> "8B" voltage is sourced at the output side of RFC16.
>
> If you do not have 8 volts at the thermistor board pin 8, then
>
> investigate the stripping and tinning of the RFC16 leads.
>
> Once you have 8 volts at the thermistor board (RP3 position) pin 8, then
>
> recheck the voltage at U6 pin 5 - it should be quite close to 4 volts.
>
> 73,
>
> Don W3FPR
>
>

Don Schroder

Re: K2 Alignment and Test, Part II issues

Don,

All three test points are not zeros. TP1 reads a solid 4918.88, TP2 reads between flickering 267 & 289, TP3 reads all zeros.
The resistance from the source of Q19 to ground is 280 ohms.

I did make an interesting discovery when I took voltages again. U4, pin 5 (SDO) is 0 volts, pin 7 (SCK) is 4.8 volts. U5, pin 1 (SCK) is 4.8 volts, pin 2 (SDO) is 0 volts. These pins are just opposite what they should be (what does SDO and SCK represent?). Looks like something that is directional got switched?

Sounds like we are making progress, but still a possible PLL problem?

Thanks!
Don, KE0PVQ

Sent from Mail<https://go.microsoft.com/fwlink/?LinkId=550986> for Windows 10

From: Don Wilhelm<mailto:[hidden email]>
Sent: Thursday, September 27, 2018 4:11 PM
To: Don Schroder<mailto:[hidden email]>; [hidden email]<mailto:[hidden email]>
Subject: Re: [Elecraft] K2 Alignment and Test, Part II issues

Don,

While in CAL FCTR, try the probe in TP3 and TP1 and TP2. If you have a
zero reading in all 3 places, you most likely have a bad probe.
Yes you might have a PLL problem, but that is not certain yet. One quick
check is to measure the resistance from the source of Q19 to ground. If
it is high or infinite, check the leads of RFC14 like you did for
RFC16. The normal resistance is a bit more than 270 ohms.

73,
Don W3FPR

On 9/27/2018 4:41 PM, Don Schroder wrote:

Don Wilhelm

Re: K2 Alignment and Test, Part II issues

Don,

It seems you are having trouble with both the PLL Reference Oscillator
and the BFO (TP2 should be near 4915kHz).
The VFO TP1 is apparently oscillating if you have a frequency of
4918.88, but that frequency is not correct.

Tackle the PLL Reference first.
OK, the PLL Reference Oscillator is not oscillating for one reason or
another. Chek all the components in the circuit for proper values and
good soldering. You apparently can follow the schematic, if for no
other reason than to identify components in a circuit - that is helpful
information.
Make certain D18 is installed with the proper orientation, and that C84
and C85 are 120pF (marked 121).

73,
Don W3FPR

On 9/27/2018 8:07 PM, Don Schroder wrote:

>
> Don,
>
> All three test points are not zeros. TP1 reads a solid 4918.88, TP2
> reads between flickering 267 & 289, TP3 reads all zeros.
>
> The resistance from the source of Q19 to ground is 280 ohms.
>
> I did make an interesting discovery when I took voltages again. U4,
> pin 5 (SDO) is 0 volts, pin 7 (SCK) is 4.8 volts. U5, pin 1 (SCK) is
> 4.8 volts, pin 2 (SDO) is 0 volts. These pins are just opposite what
> they should be (what does SDO and SCK represent?). Looks like
> something that is directional got switched?
>
> Sounds like we are making progress, but still a possible PLL problem?
>
> Thanks!
>
> Don, KE0PVQ
>
> Sent from Mail <https://go.microsoft.com/fwlink/?LinkId=550986> for
> Windows 10
>
> *From: *Don Wilhelm <mailto:[hidden email]>
> *Sent: *Thursday, September 27, 2018 4:11 PM
> *To: *Don Schroder <mailto:[hidden email]>;
> [hidden email] <mailto:[hidden email]>
> *Subject: *Re: [Elecraft] K2 Alignment and Test, Part II issues
>
> Don,
>
> While in CAL FCTR, try the probe in TP3 and TP1 and TP2. If you have a
>
> zero reading in all 3 places, you most likely have a bad probe.
>
> Yes you might have a PLL problem, but that is not certain yet. One quick
>
> check is to measure the resistance from the source of Q19 to ground. If
>
> it is high or infinite, check the leads of RFC14 like you did for
>
> RFC16. The normal resistance is a bit more than 270 ohms.
>
> 73,
>
> Don W3FPR
>
> On 9/27/2018 4:41 PM, Don Schroder wrote:
>
> >
>
> > Don,
>
> >
>
> > Thank you for the excellent advice! I went to the bottom of the board
>
> > and checked the resistance between the ends of RFC16. It was infinite,
>
> > so I rewound RFC16 and ensured the leads were cleaned good. After
>
> > reinstalling, I now have 4.~ votes at U6 pin 5, and 8.~ at pin 8. Pin
>
> > 8 of the Thermistor Board has 8.~ volts, too.
>
> >
>
> > Now, when I select CAL FCTR and enable the frequency counter, the
>
> > counter shows 00000.00. I believe this tells me there is a problem
>
> > with the PLL Reference Oscillator. I will continue to look at those
>
> > components. Any other suggestions?
>
> >
>
> > Thanks!
>
> >
>
> > Don, KE0PVQ
>
> >
>
> > Sent from Mail <https://go.microsoft.com/fwlink/?LinkId=550986> for
>
> > Windows 10
>
> >
>
> > *From: *Don Wilhelm <mailto:[hidden email]>
>
> > *Sent: *Thursday, September 27, 2018 1:34 PM
>
> > *To: *Don Schroder <mailto:[hidden email]>;
>
> > [hidden email] <mailto:[hidden email]>
>
> > *Subject: *Re: [Elecraft] K2 Alignment and Test, Part II issues
>
> >
>
> > Don,
>
> >
>
> > You apparently have a problem with the thermistor board - or the 8 volts
>
> >
>
> > to it.
>
> >
>
> > A "voltage rail" are those PC traces that carry voltage to various parts
>
> >
>
> > of the circuit.
>
> >
>
> > In the K2, there is one for 12 volts, another for 8 volts and another
>
> >
>
> > for 5 volts.
>
> >
>
> > On the schematic they are labeled "12V", "8A" and "5V" respectively.
>
> >
>
> > The main 8 volt and 5 volt regulators are on the Control Board. You will
>
> >
>
> > find an "5B" voltage rail at the output of U8 on the RF Board and the
>
> >
>
> > "8B" voltage is sourced at the output side of RFC16.
>
> >
>
> > If you do not have 8 volts at the thermistor board pin 8, then
>
> >
>
> > investigate the stripping and tinning of the RFC16 leads.
>
> >
>
> > Once you have 8 volts at the thermistor board (RP3 position) pin 8, then
>
> >
>
> > recheck the voltage at U6 pin 5 - it should be quite close to 4 volts.
>
> >
>
> > 73,
>
> >
>
> > Don W3FPR
>
> >
>
> >
>

Don Schroder

Re: K2 Alignment and Test, Part II issues

Hi Don,

I finally got some time to check your suggestions. D18 is oriented properly, and it looks like C84 & C85 are marked 121 (kind of hard to read since they are installed). So I thought I would check voltages for the PLL Reference Oscillator circuit. Didn’t take long to find 7.5 volts going into X1 (the crystal) and 0 volts coming out! I resoldered the pins to ensure no cold joints, and still 0 volts coming out. Do crystals go bad, or is it possible I burned it up by too much heat on the casing when grounding it? I think I will need a new one before I can check the BFO.

Thanks!
Don, KE0PVQ

Sent from Mail<https://go.microsoft.com/fwlink/?LinkId=550986> for Windows 10

From: Don Wilhelm<mailto:[hidden email]>
Sent: Thursday, September 27, 2018 7:34 PM
To: Don Schroder<mailto:[hidden email]>; [hidden email]<mailto:[hidden email]>
Subject: Re: [Elecraft] K2 Alignment and Test, Part II issues

Don,

It seems you are having trouble with both the PLL Reference Oscillator
and the BFO (TP2 should be near 4915kHz).
The VFO TP1 is apparently oscillating if you have a frequency of
4918.88, but that frequency is not correct.

Tackle the PLL Reference first.
OK, the PLL Reference Oscillator is not oscillating for one reason or
another. Chek all the components in the circuit for proper values and
good soldering. You apparently can follow the schematic, if for no
other reason than to identify components in a circuit - that is helpful
information.
Make certain D18 is installed with the proper orientation, and that C84
and C85 are 120pF (marked 121).

73,
Don W3FPR

On 9/27/2018 8:07 PM, Don Schroder wrote:

Don Wilhelm

Re: K2 Alignment and Test, Part II issues

Don,

The voltage is likely coming through RP2 and making its way through
L31. That is not the problem.
If you want to verify that it is that path, read it while rotating the
VFO through a 10 or 12 kHz range. It should vary.

When the crystal oscillates, you should obtain a frequency at TP3. That
is your next challenge.
As I said in the last email, measure the resistance at the source of
Q19. It should be near 270 ohms.

73,
Don W3FPR

On 9/29/2018 4:02 PM, Don Schroder wrote:

>
> Hi Don,
>
> I finally got some time to check your suggestions. D18 is oriented
> properly, and it looks like C84 & C85 are marked 121 (kind of hard to
> read since they are installed). So I thought I would check voltages
> for the PLL Reference Oscillator circuit. Didn’t take long to find 7.5
> volts going into X1 (the crystal) and 0 volts coming out! I resoldered
> the pins to ensure no cold joints, and still 0 volts coming out. Do
> crystals go bad, or is it possible I burned it up by too much heat on
> the casing when grounding it? I think I will need a new one before I
> can check the BFO.
>
> Thanks!
>
> Don, KE0PVQ
>
>

Don Schroder

Re: K2 Alignment and Test, Part II issues

Don,

I’m now confused. I did measure the resistance at the source of Q19, which measured 280 ohms.

Will voltage pass through a crystal only when it oscillates? I got excited when I saw the voltage on
both sides of L31 was 7.5 volts, but the voltage on both sides of diode D18 was zero.

I very much appreciate your help. I apologize if I am asking dumb questions, I’m trying to teach
this 75 year old brain. I’ll rotate the VFO and see what happens. I have much to learn!

Thanks much!
Don, KE0PVQ

Sent from Mail<https://go.microsoft.com/fwlink/?LinkId=550986> for Windows 10

From: Don Wilhelm<mailto:[hidden email]>
Sent: Saturday, September 29, 2018 3:38 PM
To: Don Schroder<mailto:[hidden email]>; [hidden email]<mailto:[hidden email]>
Subject: Re: [Elecraft] K2 Alignment and Test, Part II issues

Don,

The voltage is likely coming through RP2 and making its way through
L31. That is not the problem.
VFO through a 10 or 12 kHz range. It should vary.

When the crystal oscillates, you should obtain a frequency at TP3. That
is your next challenge.
As I said in the last email, measure the resistance at the source of
Q19. It should be near 270 ohms.

73,
Don W3FPR

On 9/29/2018 4:02 PM, Don Schroder wrote: