++++++++++++++++++++++++ Date: Sun, 7 Apr 2002 10:02:25 -0600 (CST) From: Bruce Rattray To: Tom Hammond =?iso-8859-1?Q?N=D8SS?= Cc: Subject: Re: [Elecraft] K2#2032 Hello Tom and everyone else who replied to my K2#2032 problem...all is well now...thank you all for your advice... I followed everyone's advice...I took the heat sink off...then I held the Q7 & Q8 bolts in with my left hand and carefully tipped the K2 over so the bottom was facing up... ...with my right hand I placed a jewellers' loupe so I could see a magnified view of the thermal pads... ...on the bottom of Q7 was a very small aluminum "shard" as Tom put it, that I couldn't see with my normal vision...how did it get there?...I'll never know...I can only guess that my fingers picked it up from my workbench and the shard transferred to the thermal pad while placing it in position on Q7... ...so I wet the tip of my finger and pressed it on the shard and removed it...then I continued with my wet finger to carefully wipe the thermal pad surfaces until I was satisfied that both of them looked clear under the loupe... ...then I checked the shoulder washer and other hardware for Q7 & Q8 to make sure everything was aligned there... ...then after I slipped the heat sink back on, I did a continuity check from both collectors to ground after I put on and tightened EACH nut and bolt until all was reassembled... ...then I plugged in my Astron supply, attached the dummy load and fired it up and the Elecraft display came on and shortly thereafter switched to a frequency readout... ...I will now proceed with the alignment which begins on page 71 right after I hook up a paddle... ...THANKS AGAIN EVERYONE!... ..72/73 - Bruce (VE5RC+VE5QRP) QRP-C#1 QRP-L#886 ARCI#9683 Zombie#272 A-1 Operator Club - 10/10# 944 - QRP Borg#1 - Whiner#10 - - VE5QRP SOC#11 - VE5RC SOC#12 - oo#148 - K2#2032 - COG#15 - "QRP! How sweet it is!" "I am da man wit "DAH" paddle!" == orig note Date: Sun, 07 Apr 2002 09:34:47 -0500 To: Bruce Rattray , elecraft at mailman.qth.net From: Tom Hammond =?iso-8859-1?Q?N=D8SS?= Subject: Re: [Elecraft] K2#2032 Bruce: >...did the collector to ground check again on Q7 & Q8...a short to >ground...[heart pounding and that ol sinking feeling in the pit of my >stomach]...arrrrgh...whimper... >...unhooked everything and backed off the Q7 & Q8 nuts and re-tightened >them finger tight only... >...hooked everything back up...took in a breath of air...turned on the >Astron supply and then turned on the K2...the LCD lite normal...Elecraft >was displayed and then the 40 mtr frequency popped up...whew... >...so it looks like "finger tight only" is the word for the finals...the >thermal pads and shoulder washers look ok but I'll check again in the >morning..oh, I did the collector to ground check again before turning the >power on again and the short was gone... Finger-tight may well NOT be snug enough to provide adequate heatsinking. >...question is, did my short condition blow the finals?... Did it 'blow' them? Shouldn't have... but it probably DID take them to ground... this would be expected if you managed to short THRU the thermal-conductive pad... because this would have taken the DC line directly to ground. Generally, the mounting nut should be tightened 'securely' but NOT within in inch of it's life, as many of us (including myself) are wont to do. Check the insulating pad for any small (tiny) shards of aluminum or anything which might have snuck in between it and the back tab of the transistor, or between it and the heatsink. Doesn't take much, to cause something like this to punch thru the insulator. Also check to ensure that you have all of the associated hardware properly installed, and in the proper order. >it's late so I'll wait until tomorrow and then see how the alignment >goes...I'm sure it will tell me if anything is permanently wrong, like >blown finals... Chances are they are NOT damaged, Bruce. 73, Tom Hammond N0SS == orig note == Date: Sun, 07 Apr 2002 19:07:03 +1200 From: Ron ZL1TW Subject: Fwd: Re: [Elecraft] K2#2032 To: Elecraft > >Subject: Re: [Elecraft] K2#2032 > >Hi Bruce, > My guess would be you have a small piece of swarf of some > kind between the thermal pad and ground , and tightening the nut is > puncturing the pad on one or both transistors. You will need greater than > "finger tight" on the bolts to have an effective thermal connection. >If such a short was the cause I doubt you will have dorked the >transistors...it would be a straight supply/short cct current flow ...not >through the devices at all. >Cheers......Ron ZL1TW > >At 12:23 AM 4/7/02 -0600, you wrote: >>.....snippety snip.....snippety snip........ >> ...question is, did my short condition blow the finals?...it's late so >>I'll wait until tomorrow and then see how the alignment goes...I'm sure it >>will tell me if anything is permanently wrong, like blown finals... == orig note == Date: Sun, 7 Apr 2002 00:23:31 -0600 (CST) From: Bruce Rattray To: Elecraft Subject: [Elecraft] K2#2032 I have done the pre-install for the options for my K2 and moved on to install the heak sink and get ready for the next alignment starting on page 71. I did the ohmmeter check of the collectors to ground from Q7 & Q8 and all was well...I had finger tightened the nuts on the finals and thought a gentle tightening with my pliers was in order; nothing hard just snug... ...hooked up my dummy load and my Astron power supply and set the POWER control fully CCW... ...turned the Astron supply ON and then turned the K2 ON...during the next second or so, I noticed no green lcd and the voltage meter on the Astron took a dive down, the current meter took a jump up, so I switched the K2 off as quickly as I could react... ...did the collector to ground check again on Q7 & Q8...a short to ground...[heart pounding and that ol sinking feeling in the pit of my stomach]...arrrrgh...whimper... ...unhooked everything and backed off the Q7 & Q8 nuts and re-tightened them finger itght only... ...hooked everything back up...took in a breath of air...turned on the Astron supply and then turned on the K2...the LCD lite normal...Elecraft was displayed and then the 40 mtr frequency popped up...whew... ...so it looks like "finger tight only" is the word for the finals...the thermal pads and shoulder washers look ok but I'll check again in the morning..oh, I did the collector to ground check again before turning the power on again and the short was gone... ...question is, did my short condition blow the finals?...it's late so I'll wait until tomorrow and then see how the alignment goes...I'm sure it will tell me if anything is permanently wrong, like blown finals... ..72/73 - Bruce (VE5RC+VE5QRP) QRP-C#1 QRP-L#886 ARCI#9683 Zombie#272 +++++++++++++++++++++ From: "K7FD N7SG" To: rattray at gpfn.sk.ca Cc: elecraft at mailman.qth.net Subject: Re: [Elecraft] K2#2032 (shards!) Date: Sun, 07 Apr 2002 10:18:20 -0700 During construction of my third Elecraft kit, I noticed I was seeing more 'shards' and fine metal bits and pieces showing up. It seems my Radio Shack 'nippers' were beginning to dull. I bought a new pair and no more problem. Apparently I wasn't getting a nice clean snip when clipping leads... ...now the only shards I have are the nice chocolate one's in my Ben and Jerry's ice cream! 73 John K7FD www.hamhobby.com >From: Bruce Rattray >...on the bottom of Q7 was a very small aluminum "shard" as Tom put it, >that I couldn't see with my normal vision...how did it get there?...I'll >never know... +++++++++++++++++++ +++++++++++++++++++