[Elecraft] K2 Line Out Mods

Wed Jan 29 15:40:01 EST 2014

Kevin,

With the Elecraft pinout, pin 5 is defined as FUNC - which was never 
implemented in the K2, so that is the choice for use as an "unused mic pin".
Caution, there is circuitry connected to the FUNC input, so that must 
remain isolated - in other words, if there is a jumper from FUNC to 5 on 
the microphone configuration header, it must be removed.  You can 
connect the audio out wire to the pin marked "5", and only that pin.

On the ground situation, the proximity of the Control Panel Ground and 
the Front Panel ground is such that a direct ground connection is not 
necessary - at least it works that way in my K2.  If I wire to the rear 
panel, I will run a wire for the AF as well as the ground - that also 
works well.

73,
Don W3FPR

On 1/29/2014 2:21 PM, Kevin Crossett wrote:
> I have been messing about with this board for a while, but have not had
> success hooking it up the rig yet. I downloaded the schematic that Sean
> produced ... nice job ... and made up a board using the laser toner method
> described by K7QO. I did see one small issue with the board. The OUT label
> is actually labeled GND ... a minor oversight. Otherwise the board looks
> FB.
>
> Two questions about using pin 5 from the microphone header ...
>
> Is the ground from the audio out board still used? If so, where does it
> connect?
>
> Also, while I don't use a mic (CW only at this point), if I attach the
> audio out to pin 5, can I still plug in an Elecraft-wired mic without
> unplugging the audio out connector from the header?
>
> Thanks for any insight...
>
> Kevin
> KK4LSG
>
>
> On Mon, Jan 27, 2014 at 6:51 PM, Don Wilhelm <w3fpr at embarqmail.com> wrote:
>
>> 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.
>>>
>>>
>>>
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