[Elecraft] K2 Line Out Mods

[Don Wilhelm]

Sean,

The circuit is simple enough to build on perfboard if you don't want to 
go to the trouble of making a board.  If you do make boards, you might 
want to consider making additional board and offering them for sale.  
There are occasional requests for those boards.

Build the version which lays the components flat on the board and attach 
it to the back of the Control Board.  That way everything except the 
audio output is on the Control Board making the Control Board easy to 
remove for servicing - plus it fits easily when the KPA100 is 
installed.  For the output connection, yes an unused microphone pin is 
an ideal place (for the Elecraft microphones, use pin 5).  Use a wire 
that is an adequate length to allow the Control Board to be removed 
sufficiently that you can reach the microphone configuration header on 
the back of the Front Panel.  You can solder the audio output wire to 
one of the 'computer' type jumpers that will plug right into the 
microphone configuration header - make certain the 'jumper' is plugged 
only into the side that is closest to the microphone jack.

The only difference between Pauli's (SK) AF take off point and the one I 
used is that Pauli's is prior to the muting transistors in the K2 and my 
points are after the muting transistors.
If you prefer that the AF not be muted during TX, then you can still 
attach to the back of the Control Board at the rear of CB J2 pins 1 and 
2 - and is quite independent of the KDSP2 (or KAF2) option.

I might add that Pauli did buy one of my boards - I asked him "Why since 
he had a wonderful interface already", and he replied that my Fixed 
Audio Output board was an easy and simple solution.

Good luck on getting that license.

73,
Don W3FPR


On 1/27/2014 6:08 PM, Sean Michael Johnston wrote:
> Hello All.
>
> I’m a newbie here and about to embark on building a K2. One of the many uses I have planned for the radio is to send emails over Winlink 2000 while at sea on a sailboat.
> I'd like to communicate with the SignaLink USB sound card through Winmor first and then eventually with a PACTOR 3 or 4 modem.
>
> I was thinking of building the fixed audio out designed by W3FPR & NØSS. My plan is to fabricate a pcb using the laser printer transfer method. I have recreated NØSS’s layout as a printable pdf (https://drive.google.com/file/d/0B_D41ceK5uSqM3VGa05BWXBhYkE/edit?usp=sharing), and am thinking I’ll run the line out to pin 5 of the  8-pin mic connection so I can have a single cable between the K2 and the SignaLink.
>
> My question is where is the best point in the K2 to source the AF inputs from? Is it cleaner to tap into the control board as is illustrated by W3FPR’s great instructions (http://www2.opparc.org/mirrors/n0ss/www.n0ss.net/w3fpr_fixed_af_output_for_the_k2_v2r1.pdf), or would it be a better signal if I tap into the KDSP2  board as recommended by EA3BLQ (http://www.qsl.net/ea3blq/downloads/k2di-pci_const_manual.pdf) for his Sound Card Interface? And is this the best way to get a line out from the K2, or has there been any newer advancements along those lines?
>
> I realize that I’m building a legacy product here, but from the activity I’ve seen on this mailing list, it’s definitely not dead yet.
>
>