[Elecraft] Heil Boomset Adapter Info

[Kenneth E. Harker]

On Mon, Jun 23, 2003 at 08:47:38AM -0400, Mark S. Adams, P.E. wrote:
> Hi Gang,
> 
> As we all get ready for FD, my ONE need is to make my Heil Boomset work 
> with the K2.  Is the Heil AD1K the correct part?

Yes, but there's a little more to it if you are already using the 
Elecraft MH2 hand microphone.  Here's what I did:

http://www.wm5r.org/k2-100/microphones.html

If you've put the 5.6K resistor that comes with the Elecraft MH2 across 
pins 1 and 6 on the back side of the microphone jack on the front panel
board, you are sending 5VDC on the mic audio line.  This is necessary for
an elecret mic like the Elecraft MH2.  The Heil Proset (and the Heil Boomsets,
unless it's one specifically made for Icom rigs - see "elecret for ICOM"
on http://www.heilsound.com/bm10.htm) is not an electret, and the 5VDC 
will bias the mic element into total insensitivity.  You will either need 
to add a DC blocking capacitor across the mic audio line of your headset 
or Heil adaptor, or move the 5.6K resistor inside the rig to someplace 
inside the Elecraft MH2.
 
-- 
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Kenneth E. Harker      "Vox Clamantis in Deserto"      kharker@cs.utexas.edu
University of Texas at Austin                   Amateur Radio Callsign: WM5R
Department of the Computer Sciences          Central Texas DX & Contest Club
Taylor Hall TAY 2.124                         Maintainer of Linux on Laptops
Austin, TX 78712-1188 USA            http://www.cs.utexas.edu/users/kharker/
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