Building K2 #6321

Note! this is a huge 39mb file allow it to load....

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Even before my kit arrived I proceeded to put together a "Construction Manual".
It contains all the needed material to build this K2. I did this so as not to
deface the original manuals and/or instruction sheets. The manual was printed
from PDF files downloaded from the Elecraft web site.
After printing they were placed in a three ring binder to allow easy removal of the individual pages

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K2 #6321 arrived on 28 Nov 07

The first thing is to inventory the kit to be certain everything is here.
The parts list is Appendix A

K2 Packing Box Parts List complete.

Items inside back of manual complete.

K2 Control Board Parts List p/n E850002

Page #1 complete

Page #2 complete

Page #3 complete

Page #4 complete

K2 Front Panel Board Parts List p/n E850003

Page #1 complete

Page #2 complete

Page #3 complete

K2 RF Board Parts List p/n E850001A & E850001B

Page #1 complete

Page #2 complete

Page #3 complete

Page #4 complete

Page #5 complete

Page #6 complete

Page #7 complete

Page #8 complete

Page #9 complete

Page #10 complete

K2 Misc Bag Parts List p/n E850004

Page #1 complete

Page #2 complete

K2 RF Probe Parts List p/n E850036 and Wire Bag Parts List p/n E850005

Page #1 complete

It took the better part of four hours to inventory the kits parts. I only found two items that were
missing. Not really, I believe that subsitutes were issued. I fired off an email to Scott at Elecraft
for verification and should hear back from him soon. These parts were on the RF board so I have plenty of
time to verify this question. So now it's time to heat up the iron and melt some solder. One other
point that should be known. I only install one component at a time so it will take me longer to get
the job done because I triple check everything before soldering, less mistakes that way.

Actual construction begins with the Control Board on page 13 and completes on page 23 of the Rev."G" Manual

Parts are sorted and ready to start the Control Board PCB

Construction Manual

Page #14 complete

Well it took 1.75 hrs to do the work on page 14. The reason! I installed "RP5" backwards it had to be
cut out and the holes solder wicked to remove the solder and a new part ordered from Elecraft. Boy do I
feel dumb! Madelyn assures me it would go out today.

Construction Manual

Page #15 complete

Under an hour to do page #15

Construction Manual

Page #16 complete

Half an hour to do page #16. Of course not to many components here to install.

Construction Manual

Page #17 complete

Half an hour to do page #17. Just a couple of components here to install.

Construction Manual

Page #18 complete

Half an hour to do page #18. Some jumpers and some components on the bottom side.

Construction Manual

Page #19 complete

15 minutes to page #19. Just the connectors to install.

Construction Manual

Page #20 complete

20 minutes to install the remaining IC's.

Construction Manual

Page #21 complete

15 minutes to do the keying modification on the PCB bottom.

Construction Manual

Page #22 contains the resistance checks.
The Control board has been completed.

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Now The Front Panel PCB

Front Panel contruction is on pages 24 through 33 of the Revision "G" Manual.

Parts have been sorted and we're ready to start.

Construction Manual Page #23 and Page 23 is instructions on how to preform the work on page 24

Page #24 complete

1 hour and 15 minutes to install most of the components here top and bottom.

Construction Manual

page #25
Details installation of IC's Bargraph and mocriphone connector.

20 minutes to install the components.

Construction Manual

page #26
installation of standoffs and potentiometers.

Construction Manual

30 minutes to do this.

Resistance checks are on

page #29

Instructions for Front Panel completion are on

Page #30

Page #31

Page #32

Page #33

45 minutes to do this.

Front Panel Complete

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Assembly Part I

Ready to begin.

Assembly of the RF Board begins on

Page #35
Showing the installation of "D" fasteners and continues on

Page #36
also a few other components are installed.

Installing those relays take time. 1.5hrs here.

Mostly connectors installed on

Page #37

Still it required an hour.

The final inter-board connector "P1" was installed on Page #38

Along with visual inspection before resistance checks.

Instructions on assembly of the case are contained on

Page #39

Page #40

Page #41

Page #42

Assembly Part I Complete

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Alignment and Test Part I
The procedures are contained on pages

Page #43

Page #44

Page #45

Page #46

Page #47

Page #48

Sure does smile pretty!
I did notice that one led segment in the bar graph did not light. While dismantleing the case to do
Assembly Part II, I checked the Front Panel board and found an unsoldered pin on the Bar Graph LED. I hope It
solves the problem of the unlighted segment.

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The RF BOARD Assembly Part II

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Assembly Part II runs from page 49 to page 62.

A lot of resistors are installed on

Page #49

It required 2 hours and 20 mins to do this page

The PLL Upgrade (Thermister Board)instructions are on

Page #50

It required 45 mins to do this page. If you look real close you can see it in the front left corner.

Diodes variactors and transistors were installed on

Page #51

It required just an hour to do this page. Only a few more pages and I get wind 'roids. Ooohh goodie! :^)

Capacitors and IC's are installed on

Page #52

It required just an hour to do this page and I used ESD procedures when working with IC's.

I've combined

Page #53


Page #54
because instructions for the mods on the bottom of the PCB are covered on these two pages then crystals are covered after that.

The mods are in the left picture. Crystals install on right.This required just about an hour total time

OooohhhH Goodie, Next the 'roids.

Instructions are contained on

Page #55

Page #56

Page #57

and most of

Page #58 for the winding of

RFC14, RFC16, RFC11 (on the bottom) and Transformers 'T5', 'T7' and 'T6'. This required 3.5 hours to complete.
Not as difficult as anticipated. Now continueing on

Page #58


Page #59

Instructions for the completion of Part II are on

Page #60


Page #61
along with the final parts installation.

Resistance Checks are on

Page #62

This completes Assembly Part II

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Alignment and Test Part II

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A little trouble shooting was in order because of a bad solder joint on K14. Don (W3FPR) Wilhelm
once again steered me in the right direction. After that everything checked out okay. My XG1
died so I was unable to peak 40m as close as I wanted to tonight, but it can wait.

P.S. the Bar
Graph segment that didn't light up before was fixed when I found the unsoldered pin and soldered it.

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Now Assembly Part III

Pages 68 through and including page 76 will complete the RF board.

Beginning on

Page #68

Most of the resistors all of the capacitors and trimmer caps are installed. Three and a quarter hours here.

Moving quickly to

Page #69

Where we

complete the resistors, ferrite bead assemblies and the sluged tuned inductors. Just an hour here.
It is really moving fast. Nine toroids to wind and three toroidal transformers and the PA left.

Instructions for winding LPF inductors and toroidal transformers are on

Page #70

Page #71

Page #72

Only the PA remains to be installed

Instructions for installing the PA and buttoning the case for Alignment and Test Part III are on

Page #73
Page #74
Page #75
Page #76

RF Board Alignment and Test Part III next

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Alignment and Test Part III

The following is a TROUBLE SHOOTING SEQUENCE of emails
between myself and Don [W3FPR] Wilhelm.

Robert 'RC' Conley wrote:
40m transmitter alignment... 
no power out no adjustment holds  at 0.01
using internal meter w/DL-1  or WM-1 and DL-1

RX pre-alignment everything peaks nicely using N-gen

per trouble shooting checked R67/R68 okay
R66/R69 okay D9  1n5711 okay

checked T1, 2 , 3 seems right

resistance check in assembly part were good

found break in RFC7 1.5uh on first color band
could be culpert

I only have 10uh choke in junque box could I sub this to check if RFC break problem?

RC kc5wa



The lowest value that the K2 power display goes to is 0.01, so what you
are seeing is normal when there is no power output.

RFC7 along with C104 is a series tuned circuit to drain off any residual
IF signal (4915 kHz) at the output side of the bandpass filter, so it
must be a proper value.  You can just remove it for now (until you can
get a proper replacement). and go on with your troubleshooting.  The
value for RFC7 is 15 uH.

I believe the best way to proceed is to go to the Transmit Signal
Tracing steps on Page 12 of Appendix E (Troubleshooting) and measure the
RF voltages at each stage.  The only other way is to simply check
everything because there are many potential causes for no transmit - it
is much easier to try to isolate it to a particular stage.  You could
try the DC voltage checks first to be certain you have power to each of
the transmit stages.



After completing the Voltage measurements on the RF Board (page 17 REv G)
Here are those reading that jumped out at me.



Q23 behind Control board
I wonder if I wound or installed  T1 T2 T3 incorrectly


Those voltages look to be within the realm of normalcy.  
A 10% variation from the 'typical' numbers is to be expected.

The drain voltage in Q24 is normal for a K2 that is not producing 
adequate power output - the drain voltage is how the K2 controls 
the power output (it changes the BFO injection level), and your K2 
is trying to drive harder to produce power output.

So bottom line - you have something broken in the transmitter chain - 
dig out the RF probe and do the RF voltage measurements so it can be 
isolated to a particular stage.



page 12  Prep for Signal tracing
step 3
12v check D10 13.37vdc
Q5 case 13.34vdc
Q6 collector 13.34vdc
Basic voltage checks
Display  E13.3 i0.22
actual xmit mode V13.2v Current 0.60A
step 4
key down voltages on anodes
D7 should be about 8v actual 7.55
D6 near 0V actual 0.224
step 5
actual power in TUNE 0.01

Side tone works

step 3
Power Control test (VPWR line)
expected .07-2.5VDC actual 4.92vdc
step 4
 if VPWR reads too hi >4.5v
check components in RF detector...OKay

Transmit Mixer, Buffer, BPF, T-R sw
XMIT MIXER OUTPUT expected 0.016vrms..actual  0.054vrms
BUFFER OUTPUT expected 0.200vrms actual .468
BPF OUTPUT expected 0.030vrms actual 0.177vrms
T-R SWITCH #1 OUTPUTexpected 0.029vrms actual 0.176


PRE-DRIVER OUTPUT(collector/case of Q5) expected 0.120 vrms actual .794vrms
DRIVER INPUT B of Q6 expected 0.026vrms actual 0.218vrms
DRIVER OUTPUT C of Q6expected 1.8vrms actual 2.16vrms
PA INPUT Q7 expected 0.38 vrms actual 2.16 vrms
RF DETECTOR INPUT expected 2.0 vrms actual 0.013vrms

+ lead on base
B-E expected 0.600k actual 2.640k
B-C expected 0.600k actual 2.929k

- lead on base
B-E expected 1.3k actual 2.252k
B-Cexpected > 3k actually starts at open and counts down

+ lead on base
B-E expected 0.600k actual 2.650k
B-C expected 0.600k actual 2.959k

- lead on base
B-E expected 1.3k actual 2.254k
B-C expected > 3k actually starts at open and counts down


Either Q7 and Q8 are bad
*OR* there is something wrong between the Q6 collector and the bases of Q7/Q8

First check the 3-4 winding of T2
Then check R53, R54, R55, R56, C127, C128, RFC8 and RFC9.

Somewhere in that group of components or Q7/Q8 themselves you will find the problem.
Since you have no RF voltage on Q8 base and your transistor power off resistance 
checks seem to be off, it certainly could be bad transistors, but the other components 
could also cause that condition.  Also, your particular DMM may not yield the resistance 
measurements normal for most DMMs when doing a check of the diode base-emitter measurements, 
so it is hard to tell for sure.

Look carefully for a solder bridge on any of the components above.  
If you have excess solder (more than just a bit more than required to fill 
the thru-plated hole), remove the excess with solder wick and retest.

Those RF voltages that are higher than expected are normal for a K2 that is 
not delivering power output.  The K2 tries to increase the drive until it 
maxes out.  I note in your readings that all RF voltages are higher than 
expected through the Q6 collector, but the RF voltage on the Q8 base goes 
to zero (or nearly zero).

Since Q8 appears to be the troublesome component, you could remove Q8 and 
see if you get any RF output - if you do, then replacement of the PA transistors 
is in order.  Since this is a new kit, Scott will send you a pair if you send 
an email to


GM Don
I worked last night saw your message when I got in at 7:30. 
GIANTS were losing so went to bed  early 9:00
2:30am CST I could not sleep.

I checked the values of R53,R54,R55,R56 they are colour coded
correctly. and since I measure each resistor before installing them.
they were correct...

I checked the values C126,C127,C129,C130, RFC8,RFC9...
again marked correctly

Pulled the Heat sink (bottom cover) checked the Q7 & Q8 area using my
magnified lens (3.5 diopter) everything looked good EXCEPT T2 pins 3 &
4 ( they looked like toothpicks sticking up through doughnuts). I
wicked out (removed) T2 from the PCB and re-flowed ALL the joints to
be sure they  were good then cleaned the T2 holes

Most likely T2 was/is the issue. Bad components don't happen that
often. In all the Elecraft kits I've built (15+) I can only remember
one 8v regulator. Bad solder joints are more likely.

Now I'm going back to bed I'm not on call until the 22nd and I'll
rewind and install T2 later today. Then the heat sink and start over
checking for power. Thank You

Well It worked Don
I have rewound and installed T2
I now have 10+ watts output on 40m band verified with my Elecraft WM1
I was curious so cranked it up full bore and the WM1 says I have 15watts
display reads 13.6watts. Now I can finish it up

Bad solder joints will KILL IT every time.
Thank you my friend
RC kc5wa
The actual measurements of Appendix E Trouble Shooting

Page #12

Page #13

Page #14

RF Board DC Voltage checks

Appendix E Page #17

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The Final Assembly

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The final Assembly consist of installing the speaker, external speaker jack and Serial number and not much more than that.
Final Assembly is on

Page #81

Page #82

Page #83

I do plan on adding the KSB2 and KAT2. Maybe also the KAF2 is in the future

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About the


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This completes K2#6321 for now.

72 de "RC" kc5wa