[Elecraft] K2, PSK31 & microphone

[Matt Osborn]

High Mark,

The 5.6k resister came with the microphone and instructions to install
it and how to set the jumpers.

You provided the key word here, 'electret'.  I'd seen the word before,
but had thought it was a branding term rather than a functional term.
I just did a google search and now I know why the 5.6K resister is
needed.

This reminds me of 25 years ago when every software package had to
develop special code to support each of the various graphics cards
then available.  There were few standards at the time and most were
honored only in the breach.

I was surprised to find that the standard 8 pin microphone connector
is but a physical standard, not an electrical one.  It seems that
switching microphones isn't as easy as switching light bulbs.  Not
only do we have to configure differently for electret vs dynamic
microphones, but we also have to worry about PTT switches, Up Down
buttons and the like.

Choices, choices, choices...

On Fri, 29 Jul 2005 20:51:41 -0400, vze3v8dt at verizon.net wrote:

>Hi Matt,
>
>I had used my K2 with PSK31 for a while as well, lots of fun.  I had my 
>K2 microphone wired for a standard Kenwood configuration as my "big 
>radio" was a Kenwood TS-940S.  I also used two different Heil headsets 
>with the K2.  Both used the standard Kenwood plug adapter (actually I 
>built one of these rather than paying for the "official" one from 
>Heil).  One of the headsets is the ProSet Plus and the other is the HM5 
>(I think, it is a single earpiece headset with the HC5 mic element).  I 
>did not need to use a 5.6k ohm resistor to pin 6 and 5V to get these to 
>work.  I did however change one resistor on the KSB2 SSB module, R14 
>from 1k ohm to 10k ohm and I use the mic gain setting of 2.  Using PSK31 
>you apparently don't want to have any compression, so make sure you set 
>it to 1:1, although I sometimes forgot to switch over from my voice 
>setting of 3:1 and I think things still worked okay.
>
>I'm not sure why you had to use a 5.6k ohm resistor.  Did it not work 
>unless you used it?  From what I know about the Heil microphones, if it 
>is the HC5 or HC4 element it doesn't need any bias and could actually 
>harm them if there is bias.  However some mic elements (like for Icom) 
>do need the bias.  I forget if they are electret or dynamic microhones.  
>Would it hurt to leave it there?  First I'd figure you why you really 
>need it in the first place and then decide.  If you don't really need it 
>maybe now would be a good time to take it out.  I think I remember 
>somebody else on here had the voltage on pin 6 but put the resistor from 
>pin 6 to pin 1 in the microphone plug itself for the microphone that 
>needed it.  That way if you use a different mic the extra resistor is 
>not there and the K2 should still work like normal.  Actually, that 
>might be a better solution for you as well (if you decide that you do 
>need it for you Proset-K2). 
>
>73,
>
>Mark, NK8Q
>
>Matt Osborn wrote:
>
>>I'm using Ham Radio Deluxe/PSK31 Deluxe software which handles the
>>PTT, but I still need to connect from the sound card to the K2's
>>microphone jack.
>>
>>I have the Proset-K2 headset that has an 8 pin adapter that accepts
>>the monophonic Proset-K2 microphone plug.  I would like to use an
>>audio ground loop isolator to connect the sound card audio out to the
>>Proset-K2 adapter microphone plug.
>>
>>However, when I installed the Proset-K2, I had to install a 5.6K
>>resister between 5V (pin 6) to the AF (pin 1)  on the back of 8 pin
>>microphone adapter on the K2.
>>
>>I don't know the purpose of this resister; I assumed it was just a
>>pull up.  Is it safe to leave this resister in place?
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>