ELECRAFT K2

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 potentioometers.

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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The RF BOARD

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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

and

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

and

Page #59

Instructions for the completion of Part II are on

Page #60

and

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 =================================================== RC, 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. 73, Don W3FPR =================================================== After completing the Voltage measurements on the RF Board (page 17 REv G) Here are those reading that jumped out at me. REF_PIN_VDC_READING Q18...G...-1.0...0.0 ..........S....2-3...2.388 ..........D....6.3...7.662 Q20...S....0.0....0.0 ..........G...8.0....7.57 ..........D...0.0.....064 Q24...G...0.0...0.0 ..........S...1.2....1.86 ..........D...1.3...3.88 Q23 behind Control board I wonder if I wound or installed T1 T2 T3 incorrectly RC =================================================== RC, 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. 73, Don W3FPR =================================================== DON HERE ARE THE CHECKS FOR THE TRANSMITTER ------------------- 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 ALC 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, DRIVER AND PA 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 PA INPUT Q8 EXPECTED 0.38VRMS ACTUAL .001VRMS RF DETECTOR INPUT expected 2.0 vrms actual 0.013vrms PA TRANSISTOR TEST Q7 + 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 Q8 + 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 I REALLY DON'T KNOW WHAT TO THINK....RC =================================================== RC, 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 parts@elecraft.com =================================================== 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 RC =================================================== 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

cover

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This completes K2#6321 for now.
72 de "RC" kc5wa