Today I got around to installing in my K3 the audio upgrade kit that arrived a couple of weeks ago. The first part of the kit involves swapping an RFC on the main PCB with one that has a lower resistance. (FYI, I measured the resistance of the original choke as 0.4 ohms, and of the new choke as 0.1 ohms - hard to imagine the new choke would make that much difference!). The instructions give a "short" and a "long" method of installing the choke. The "short" method involves cutting a circuit board trace. I elected to do the "long" mod and timed myself. Start to finish it took 15 minutes! I highly recommend folks do the long method, and also that Elecraft delete the short method as an option. It just isn't necessary and, besides, who wants to mess up that beautiful circuit board?
The second part of the kit involves shunting two resistors with 51 ohm resistors, and here also Elecraft gives two options: one is to solder 1/8w through-hole resistors onto the IO board, and the other is to solder two tiny SMT (surface mount ) resistors piggy-back onto existing SMT resistors. The kit comes with both kinds of resistors. I elected to do the SMT version of the mod, and here I'd recommend that owners opt for the other method. I don't see any advantage to doing the SMT version. It takes a very steady hand, a very small-tipped soldering iron, and very good eyesight to piggy-back the two SMT resistors into the circuit, and I just don't see the reason for the hassle. It would take five minutes to install the through-hole resistors, and the result looks quite clean and neat. I'd recommend also that Elecraft delete the SMT option from the instructions. Took me about 30 mins to install the SMT resistors, probably about half that time to install the through-hole ones. 73, Jim W8ZR
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