Posted by
Nick Kennedy on
Aug 26, 2010; 1:54am
URL: http://elecraft.85.s1.nabble.com/K3-Modification-day-for-SN-01195-tp5463862.html
I've been storing up a list of modifications I wanted to install in my
K3 (S/N 01195, July 2008) and managed finally to do them today. Due to
the number (nine) and varying descriptions, purposes and locations in
the rig, I tried to organize my thinking by putting them in a list,
trying to see which ones I really need or want, how hard they might be
to install, and which ones might be best done together due to being on
the same board, etc. Some are documented in Elecraft's modification
kits & parts area and some in the application notes area.
I started by putting all of the PDFs into a directory of "official K3
modifications" so I could study them. The ones applicable to my K3's
vintage were -
K3AFMDKT --- Improve speaker & line out distortion and IMD
K3DSPLPF --- Active audio LPF to reduce artifacts in the audio chain,
add daughter board to DSP board
K3IOBUFFKT -- Increase signal level at I.F. output by more than 10 dB
AFOPMDKT -- Protect audio amp from short circuit or low impedance loads
App Note -- Extreme signal RX protection mod
App Note -- Protect against RF pickup at microphone connection by
bypassing RF choke
App Note -- Protect against chirp from synthesizer by increasing DDS
signal driving the PLL
App Note -- Improve immunity of RS232 and audio connections to RF by
bypassing RF chokes
App Note -- K3 SYN ALC mod. Assure enough drive when in high
temperature environment
Descriptions are my paraphrase and might not be totally accurate.
Anyway, I did all of these today and made notes on the degree of
difficulty and which ones might best work at the same time here -
http://pages.suddenlink.net/wa5bdu/k3_mods.pdfIf you have a similar vintage K3 and haven't kept up on mods, they might
be of interest.
None of them were really difficult for me, and the instructions were
complete and accurate. I should say, I assembled my K3 from a kit, I do
a lot of homebrewing but it's pretty ugly, and my vision wouldn't allow
SMT work with just my bifocals, but with a 10x jeweler's loupe jammed
into my good eye I do OK.
I did all the mods today and didn't put anything back together until I'd
finished them all. Doing it this way, it's important to bag or
otherwise segregate all of the screws or other hardware from each cover
or component removed and keep each piece in a separate place with its
own hardware.
I was most interested in the lowpass filter. I'm no golden ear, but
possibly the power of suggestion made me think I heard some of the
harshness others described. I found myself cranking the bandpass way
down toward the low end. At least preliminarily, I think I do notice
the improvement in the quality of the sound (I work CW) with the LPF
installed.
I'm pleased with Elecraft's way of publishing instructions and making
mod kits available. Not to diss any other manufacturers, but most have
a "no user serviceable parts inside" approach.
73-
Nick, WA5BDU
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