++++++++++++++++++ Reply-To: "Ron D'Eau Claire" From: "Ron D'Eau Claire" To: Subject: Re: [Elecraft] Remove the Heat Sink or Go to the Dentist? Date: Sun, 16 Jun 2002 12:21:16 -0700 > Does anyone have a solution to getting the thing back on without > shorting either of the 2 power transistors to the casing? > > Any ideas would be appreciated, because I really enjoying looking at the > inside of my K-2 :) > > Thanks > Tom > WB2QDG I've only done it once since I built my K2 and it was no problem at all. I put the K2 on its side so the screws would not fall out of the transistors when the nuts were removed. On the bottom, I removed the nuts and washers, and carefully slid the bottom panel off while holding the screw tops with my fingers so they didn't get jiggled out. Then I loosely replaced the nuts on the screws to keep the hardware in place while I worked on the K2. I never removed any hardware except the nuts. Reassembly was done the same way in reverse. Remove the nuts and, while holding two fingers on the tops of the screw heads, slid the bottom plate back on and replaced the nuts just tight enough to keep the hardware in place. After the mounting screws for the panel were tightened, the nuts were made just "snug". Remember, the nuts are simply there to ensure a good thermal connection to the bottom panel. They do not need to be very tight at all! Just snug enough to ensure there is contact between the pads and transistors for efficient heat transfer. A quick check with an ohmmeter told me that I could apply power without worrying about any sparks. Ron AC7AC K2 # 1289 ++++++++++++++++++ From: "Don Brown" To: "Tom" , "Elecraft" Subject: Re: [Elecraft] Remove the Heat Sink or Go to the Dentist? Date: Sun, 16 Jun 2002 14:46:17 -0500 Hi I have R&R the heat sink on several K2's several times adding options for= people. I remove the back hardware and the screws and nuts from the bott= om. With the radio on its side carefully push the PA mounting screws just= a little past flush with the bottom cover. Then remove the cover. As soo= n as the cover is clear push the screws back in from the top so the hardw= are does not fall off. Check the insulators for damage and make sure they= are still on the transistors and not the heat sink. Thread the nuts on t= he mounting screws loosely without lock washers and do what ever you need= to do under the cover. The insulators and hardware is held in place by t= he nuts so there is no worry about loosing anything. =20 To reinstall the heat sink remove the nuts and with the radio on it's sid= e push the screws flush with the transistors and slip the heat sink over = the BNC connector and key jack. When the holes line up push the screws in= from the top and install the lock washers and nuts. Then install the res= t of the hardware. Check the collectors to ground for shorts with a DVM b= efore powering up again. BYW while you are under the cover if you have installed the aux RF and au= x DC in connectors it is a good idea to install the DC blocking capacitor= modification on the aux RF connector. This will prevent damage to the ou= tput stage if the battery or aux power connector is plugged in to the RF = connector by mistake. The mod is - cut the run close to the aux RF connec= tor and install a .047 (473) capacitor in series with the hot side of the= connector. This mod is described in the KPA100 manual and is a good idea= to install on all K2's Don Brown KD5NDB ----- Original Message ----- From: Tom Sent: Sunday, June 16, 2002 1:35 PM To: Elecraft at mailman.qth.net Subject: [Elecraft] Remove the Heat Sink or Go to the Dentist? Hi gang, OK, given the choice, I suppose I'd rather take off the K-2's heat sink than have oral surgery, but sometimes I feel like it's a tough decision. -- snip -- Thanks Tom WB2QDG K2 s/n 1103 ++++++++++++++++++++