Dave Van Wallaghen wrote: > Hi all, > At first, I was only going to contact Ron with this as I was too > embarrassed to reveal that I had maimed the RF board on my K3. But, I > then thought maybe someone else could benefit from my experience and > public humility ;-) > > I have an early serial number #338 and needed to make the modification > to R91 on the RF board as described on page 21 of the KRX3 Installation > Manual. In doing so, I was having a hard time getting the 27 ohm > resistor lead to tack onto the (looking at Figure 20) right pad of R91. > I made multiple attempts and couldn't get a clean connection until I > eventually lifted the pad. I was using a small but short soldering tip > at 720 degrees. In my zeal to get a nicer connection, I simply played > around with it too long and with too much heat, lifted the pad. Using a > longer, narrower tip (as I am now) would probably have worked better. > > After the horror and high emotion subsided, I sat down to figure out > what could be done and hence a question as to my solution. Looking at > the schematic for the RF board, it looks like the only connection to the > right pad of R91 is pin 14 of U7. Does that seem correct to anyone else? > I removed R91 and was able to solder a 22 ohm 1/8 watt resistor to the > remaining trace of pin 14 of U7 and the pad next to R91 as outlined in > the directions. DMM measurements between U7 pin 14 and the left pad of > R91 show 22 ohms, so I'm pretty sure I was able to salvage the situation. > > I will continue with the installation this morning, but would like some > concurrence that what I've done looks correct to someone else's eyes > before I power this beast back up. > > BTW - Since I was going to install the KRX3, I decided to make the mods > for the K3 Synthesizer ALS, Rear RS232 and Audio RF mods, K3 Amp Output > Mod and the Front Panel Mic Mod. Having to somewhat disassemble the unit > for the KRX3 anyway made doing these mods very simple. And as usual, > Ron's documentation for these mods was nothing short of excellent, > including some nice tips for lining things back up to guarantee all > connectors and boards line up the way they are supposed to. As usual, my > impatience leads me to push ahead of the text to get the job done, but > if you follow everything Ron has written you will be guaranteed success. > > Also, in my original K3 installation manual, the first KSYN3 board was > not mounted with split lock washers on the non-component side of the > board. Since I made the mod to it, I did remount it with the split lock > washers as described in the KRX3 manual. I assume there is no problem > with that? > > Now, back to work... > Dave W8FGU > > _______________________________________________ > Elecraft mailing list > Post to: Elecraft@mailman.qth.net > 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 > > > Hi Dave, I installed my KRX3 just yesterday. No problem at all adding the washers to the KSYN3 board - it 'looks' much better with the additional spacers - now it sits parallel to the shield.
My K3 is a bit newer than yours (S/N 00929) and fortunately already had the proper resistor on the RF board. I was not looking forward to making that change. I will pass along one observation - you will get into this when you place the KRX3 board into the lower half of the shield box. There are break-off tabs around the perimeter of the KRX3 board. These are supposed to line up with holes in the side of the lower shield. The tabs on the left side of the KRX3 are no where near the holes.... left = as the board will sit in the K3. Reading further along in the instructions it mentions filing the tabs as needed to ensure the board does not cause the sides of the lower shield to expand too much & mess with the fit of the upper half. I ended up filing ALL the tabs flush. After noting that the tabs on the left did not match the holes, I filed them off and proceeded to fit the board into the lower cover. I felt it was just too tight, in fact had a heck of a time getting it out. After filing all the tabs flush it was still a snug fit, but the top cover went on perfectly. Another minor hitch... cycle the K3 power after you enable the KRX3 and update the firmware. I really don't know if it was the KRX3 enable or the KDVR3 I installed at the same time, but my K3 went a little batty after loading the DSP2 firmware & a power cycle fixed it right up. Oh - don't forget the mod to the KSYN3 board, my original board needed the mod! Easy one, no SMT!! (smile).. I did have one minor encounter with Mr. Murphy of Murphy's Law fame. As I started to learn and listen on the KRX3, I gave the AF gain a twist and the knob split in half. I found a knob I had salvaged from a Tek scope years ago that is a perfect fit, but someone (me) had robbed the setscrew & of course the ones in the K3 knob are different. But the crazy glue is all set up and I'll start my learning today! Best 73, Bill N2BC _______________________________________________ Elecraft mailing list Post to: Elecraft@mailman.qth.net 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
