Alignment & Test II

[C Dwight Baker]

I am back on s/n 4766 after health issues and traveling.

 

I am at the Alignment and Test II phase.  I have the kit frequency counter
plugged into P6 and TP1.

 

I go to Cal FCTR for the 4 MHz Oscillator calibration and getting 12104.49
kHz and confirmed with another frequency counter and seem to be within
tolerance as shown in the manual.

 

When I did the PLL reference oscillator range test and at 4 MHz; the
readings are 12104.45 on the high end and 12099.20 at the low end for a
difference of 5.25 whereas the manual indicates the range should be
somewhere between 9.8 and 15 kHz.

 

Adjusting C22 on the control board gives me a difference of 5.5 kHz.

 

Where or what am I looking for or better yet have I goofed in populating the
board?  Phase I testing was good.

 

I have checked each and every component installed and looked for unsoldered
joints, reheated almost all the joints and checked for solder bridges.
During assembly I soldered each component as I installed it.

 

HELPPP!

 

Dwight  W4IJY

 

 

_______________________________________________
Elecraft mailing list
Post to: [hidden email]
You must be a subscriber to post to the list.
Subscriber Info (Addr. Change, sub, unsub etc.):
 http://mailman.qth.net/mailman/listinfo/elecraft   

Help: http://mailman.qth.net/subscribers.htm
Elecraft web page: http://www.elecraft.com

[Don Wilhelm-3]

Dwight,

Don't be concerned about the setting of C22 until after you have finished
the entire build - just set it to mid-position for now.  You will want to
re-do CAL PLL and CAL FIL after you are done with the 4 MHz oscillator set
precisely to achieve good dial calibration.  The K2 does not use the 4 MHz
oscillator on a real time basis, only during CAL PLL and CAL FIL operations.

Now in to your problem.  Yes, your PLL high and low frequencies are too high
and the range is too small.
Turn your manual to the back and find the schematic for the RF Board - sheet
1.  Then find the area in the left upper corner marked PLL Reference
Oscillator.  Check all the components associated with that circuit,
especially the capacitors, varactors, and inductor L31 for proper values and
make certain they are in the correct holes.  Re-verify that D16 and D17 are
correct - D16 is the larger bodied varactor and D17 is the smaller.

After verifying the components above, go back to CAL FCTR with the probe in
TP3, tap the BAND+ button and read the high frequency, then measure the
voltage at U6 pin 1 (it should be near 8 volts).
Then tap the BAND- button and read the low frequency and measure the voltage
at U6 pin 1 (now should be near zero volts).

Did you obtain a correct frequency range? Did the voltage at U1 pin 1 change
from 8 volts to 0 volts?
Let us know what you find.

73,
Don W3FPR

> -----Original Message-----
>
> When I did the PLL reference oscillator range test and at 4 MHz; the
> readings are 12104.45 on the high end and 12099.20 at the low end for a
> difference of 5.25 whereas the manual indicates the range should be
> somewhere between 9.8 and 15 kHz.
>
>
>
> Adjusting C22 on the control board gives me a difference of 5.5 kHz.
>
>
>
> Where or what am I looking for or better yet have I goofed in
> populating the
> board?  Phase I testing was good.
>
>

_______________________________________________
Elecraft mailing list
Post to: [hidden email]
You must be a subscriber to post to the list.
Subscriber Info (Addr. Change, sub, unsub etc.):
 http://mailman.qth.net/mailman/listinfo/elecraft   

Help: http://mailman.qth.net/subscribers.htm
Elecraft web page: http://www.elecraft.com

[C Dwight Baker]

Don, I followed your suggestions and I am still at the same place I started.


I began by following the schematic as you suggested and marked each
component as I verified the correct values and type.  I found no errors (at
least I didn't but it doesn't mean I erred again).

It appears I had a solder bridge between pins 4 and 5 on U6.  I replaced D16
veractor MV209 and did not have another D17 ISV149 so the old one is still
there.

The readings remained virtually the same as before.  The voltages at U6 pin
1 were as follows:  High 12103.15, voltage 7.61; low 1209.03, voltage 3.74.

Pin 8 of the thermistor board was 7.97 and pins 6 and 7 measured 3.96.  Pin
1 measured 7.64.  The line voltage at the power plug was 14.3 volts.

I am curious why the voltage on the lower reading did not go to near zero.
Would Q19 (J310), D17 be faulty and what effect does U4 have?

I appreciate your time for leading this BOOF (burnt out old f-rt) through
the dark.

Thanks again,

Dwight W4IJY  K2 4766
-----Original Message-----
From: Don Wilhelm [mailto:[hidden email]]
Sent: Monday, August 21, 2006 9:17 AM
To: C Dwight Baker; [hidden email]
Subject: RE: [Elecraft] Alignment & Test II

Dwight,

Don't be concerned about the setting of C22 until after you have finished
the entire build - just set it to mid-position for now.  You will want to
re-do CAL PLL and CAL FIL after you are done with the 4 MHz oscillator set
precisely to achieve good dial calibration.  The K2 does not use the 4 MHz
oscillator on a real time basis, only during CAL PLL and CAL FIL operations.

Now in to your problem.  Yes, your PLL high and low frequencies are too high
and the range is too small.
Turn your manual to the back and find the schematic for the RF Board - sheet
1.  Then find the area in the left upper corner marked PLL Reference
Oscillator.  Check all the components associated with that circuit,
especially the capacitors, varactors, and inductor L31 for proper values and
make certain they are in the correct holes.  Re-verify that D16 and D17 are
correct - D16 is the larger bodied varactor and D17 is the smaller.

After verifying the components above, go back to CAL FCTR with the probe in
TP3, tap the BAND+ button and read the high frequency, then measure the
voltage at U6 pin 1 (it should be near 8 volts).
Then tap the BAND- button and read the low frequency and measure the voltage
at U6 pin 1 (now should be near zero volts).

Did you obtain a correct frequency range? Did the voltage at U1 pin 1 change
from 8 volts to 0 volts?
Let us know what you find.

73,
Don W3FPR

> -----Original Message-----
>
> When I did the PLL reference oscillator range test and at 4 MHz; the
> readings are 12104.45 on the high end and 12099.20 at the low end for a
> difference of 5.25 whereas the manual indicates the range should be
> somewhere between 9.8 and 15 kHz.
>
>
>
> Adjusting C22 on the control board gives me a difference of 5.5 kHz.
>
>
>
> Where or what am I looking for or better yet have I goofed in
> populating the
> board?  Phase I testing was good.
>
>

_______________________________________________
Elecraft mailing list
Post to: [hidden email]
You must be a subscriber to post to the list.
Subscriber Info (Addr. Change, sub, unsub etc.):
 http://mailman.qth.net/mailman/listinfo/elecraft   

Help: http://mailman.qth.net/subscribers.htm
Elecraft web page: http://www.elecraft.com

[C Dwight Baker]

Don, thanks for the help, at least I think we are getting close to solving
this mystery to me.  I can converse with you on tubes, but this solid state
stuff is new to me.  Shows you how old I is.

Pin 1 of U1 has 6 volts present and will not go to zero as you suggested.
Pin 3 of U1 reads zero.  As you indicated that is my problem.

Following the steps in the manual and your advice I was able to get the high
reading of 12101.18 and the low 12091.42. The following voltages are:  U6,
Pin 1 high 7.64v and low 11.4 microvolts (?); U6 Pin 3 high 4.06v and low
11.4 microvolts.  I measured Pin 20 of U6 to be 6 volts.

I lifted R19 and the readings were 4.08 before and 7.64 afterwards.

I removed the thermistor board and checked the resistors and found no
errors.  I examined the board around the thermistor and found no solder
bridges as you suggested I might have.

Anyway, I think you are about to resolve my issues to which I appreciate.

Dwight  W4IJY  K2 #4766
-----Original Message-----
From: Don Wilhelm [mailto:[hidden email]]
Sent: Monday, August 21, 2006 10:32 PM
To: C Dwight Baker
Subject: RE: [Elecraft] Alignment & Test II

Dwight,

The real problem is that U1 pin 1 is not going to zero.  Now take a tiny
step to try to discover the cause - do the same test of the PLL range (you
can ignore the frequencies for this), but check the voltage at U6 pin 3 when
the BAND+ button is tapped and also when the BAND- button is tapped.  We
want to see the voltage at pin 3 go from about 4 volts to about zero volts.

If you do get the 0 to 4 volt swing at pin 3, then the firmware and DAC are
doing the job properly, you will find the problem on the thermistor board,
and the most likely is a solder bridge between pins 5 and 6 - the pads get
quite close to each other there and a solder bridge is easy to create.

The 0 to 4 volt swing at U6 pin 3 should make the voltage at U6 pin 1 swing
from 0 to 8 volts if the resistors in the op amp circuit (mainly the
thermistor board) are correct.  If you need to convince yourself that the
pin 1 output is not being loaded down, just lift one end of R19 and repeat
the test.  U6 should have twice as much voltage on pin 1 as is put onto pin
3 when all is well with the resistor network.


73,
Don W3FPR

> -----Original Message-----
> From: [hidden email]
> [mailto:[hidden email]]On Behalf Of C Dwight Baker
> Sent: Monday, August 21, 2006 8:52 PM
> To: [hidden email]
> Subject: RE: [Elecraft] Alignment & Test II
>
>
> Don, I followed your suggestions and I am still at the same place
> I started.
>
>
> I began by following the schematic as you suggested and marked each
> component as I verified the correct values and type.  I found no
> errors (at
> least I didn't but it doesn't mean I erred again).
>
> It appears I had a solder bridge between pins 4 and 5 on U6.  I
> replaced D16
> veractor MV209 and did not have another D17 ISV149 so the old one is still
> there.
>
> The readings remained virtually the same as before.  The voltages
> at U6 pin
> 1 were as follows:  High 12103.15, voltage 7.61; low 1209.03,
> voltage 3.74.
>
> Pin 8 of the thermistor board was 7.97 and pins 6 and 7 measured
> 3.96.  Pin
> 1 measured 7.64.  The line voltage at the power plug was 14.3 volts.
>
> I am curious why the voltage on the lower reading did not go to near zero.
> Would Q19 (J310), D17 be faulty and what effect does U4 have?
>
> I appreciate your time for leading this BOOF (burnt out old f-rt) through
> the dark.
>
> Thanks again,
>
> Dwight W4IJY  K2 4766
> -----Original Message-----
> From: Don Wilhelm [mailto:[hidden email]]
> Sent: Monday, August 21, 2006 9:17 AM
> To: C Dwight Baker; [hidden email]
> Subject: RE: [Elecraft] Alignment & Test II
>
> Dwight,
>
> Don't be concerned about the setting of C22 until after you have finished
> the entire build - just set it to mid-position for now.  You will want to
> re-do CAL PLL and CAL FIL after you are done with the 4 MHz oscillator set
> precisely to achieve good dial calibration.  The K2 does not use the 4 MHz
> oscillator on a real time basis, only during CAL PLL and CAL FIL
> operations.
>
> Now in to your problem.  Yes, your PLL high and low frequencies
> are too high
> and the range is too small.
> Turn your manual to the back and find the schematic for the RF
> Board - sheet
> 1.  Then find the area in the left upper corner marked PLL Reference
> Oscillator.  Check all the components associated with that circuit,
> especially the capacitors, varactors, and inductor L31 for proper
> values and
> make certain they are in the correct holes.  Re-verify that D16
> and D17 are
> correct - D16 is the larger bodied varactor and D17 is the smaller.
>
> After verifying the components above, go back to CAL FCTR with
> the probe in
> TP3, tap the BAND+ button and read the high frequency, then measure the
> voltage at U6 pin 1 (it should be near 8 volts).
> Then tap the BAND- button and read the low frequency and measure
> the voltage
> at U6 pin 1 (now should be near zero volts).
>
> Did you obtain a correct frequency range? Did the voltage at U1
> pin 1 change
> from 8 volts to 0 volts?
> Let us know what you find.
>
> 73,
> Don W3FPR
>
>
> > -----Original Message-----
> >
> > When I did the PLL reference oscillator range test and at 4 MHz; the
> > readings are 12104.45 on the high end and 12099.20 at the low end for a
> > difference of 5.25 whereas the manual indicates the range should be
> > somewhere between 9.8 and 15 kHz.
> >
> >
> >
> > Adjusting C22 on the control board gives me a difference of 5.5 kHz.
> >
> >
> >
> > Where or what am I looking for or better yet have I goofed in
> > populating the
> > board?  Phase I testing was good.
> >
> >
>
>
>
> _______________________________________________
> Elecraft mailing list
> Post to: [hidden email]
> You must be a subscriber to post to the list.
> Subscriber Info (Addr. Change, sub, unsub etc.):
>  http://mailman.qth.net/mailman/listinfo/elecraft
>
> Help: http://mailman.qth.net/subscribers.htm
> Elecraft web page: http://www.elecraft.com
>
>
> --
> No virus found in this incoming message.
> Checked by AVG Free Edition.
> Version: 7.1.405 / Virus Database: 268.11.4/424 - Release Date: 8/21/2006
>
>

_______________________________________________
Elecraft mailing list
Post to: [hidden email]
You must be a subscriber to post to the list.
Subscriber Info (Addr. Change, sub, unsub etc.):
 http://mailman.qth.net/mailman/listinfo/elecraft   

Help: http://mailman.qth.net/subscribers.htm
Elecraft web page: http://www.elecraft.com