[Elecraft] [K3] Modification day for SN 01195

[Nick-WA5BDU]

  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.pdf

If 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