[Elecraft] W0AV K2 headset mods

Sun Feb 16 22:57:00 2003

Hi,
Thanks all for the heads up on the Radio Shack headset, it works fine.
I haven't
run quality tests with folks that know my voice, but the Q's I've made
so far
seem to indicate that the audio quality is great. I decided to finish up
the Rev A
to B changes last night, and while I was at it I made some changes. (I
think I've
had the covers off of the K2 more than on it! It's fun to work on your
own radio
and make mods).
After the A to B mods I added a wire from the center pin of the AF gain
pot to pin 5
(through a 10k resistor) of the mic connector to bring audio out through
the mic
connector for PSK.  I had previously done the 'scratchy' pot mod and was
able
to grab the constant level audio signal from this point.  I also pulled
the
shorting pin from the mic configuration header.  All are jumpered now
straight across
except the one that goes to pin 5.
I made up a new mic cable for the Radio Shack headset that provides the
5V from pin 6
to run the electret mic in the headset. I used a 560 ohm resistor and a
1uf tantalum
cap as W0AV did as outlined below.  As part of this new cable I also
brought out the PTT
and AF out to a 1/4" phone jack and 1/8" phone jack respectively.  The
PTT can be
used with a foot switch or be used for PSK PTT.
Another note, with the Elecraft MH2 you are supposed to add a resistor
between pins 6 and
1 of the front panel mic connector.  I found it to be more flexible to
mount this
resistor in the mic's connector instead.  That way I could use my other
microphones
without worrying about the 5V on pin 1.
I hope this helps anyone thinking of getting these $3 headset/mics -
they do work
pretty well and are nice and small for travel.
73, Mike W1USN
=20
-----Original Message-----
From: [email protected]
[mailto:[email protected]] On Behalf Of Mike KW1ND
Sent: Saturday, February 15, 2003 11:56 AM
To: [email protected]; [email protected]; [email protected]
Cc: qrp; [email protected]
Subject: [Elecraft] W0AV K2 headset mods

Good morning. Several have requested George W0AV's Radio Shack headset
mod=20
info. His post was for model 33-1107, while the one on sale (with
coupon)=20
is 33-1171.  I haven't tried the mod yet, but odds are it will work just

fine.  I don't have the original email in electronic form (just printed=20
out), and apparently it's not possible to search QRP-L after the year=20
2000.  Here's a summary of George's email. It assumes your K2 is set up
for=20
Kenwood compatibility.

1.	3.5mm headset plug is OK
2.	Remove mic plug, noting which wire goes where. It SEEMS that the
mic=20
lead is on the ring of the plug as shipped.
3.	Attach tantalum cap (George used a 0.1uF) to pin 1 on the 8-pin
mic plug=20
with positive side of cap to mic lead.
4.	560 ohm 1/4 watt resistor from pin 5 of 8-pin mic plug to mic
side of=20
tantalum cap.
5.	Shield to pin 7 of 8-pin mic plug.
6.	Ensure leads are insulated with tape when inserting in mic plug
body.

George stated his headset worked great with VOX mode, and he just sent
me=20
an email reporting his headset is still working just fine.
73,

Mike Boice, KW1ND
Nampa, Idaho

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