[Elecraft] mic pin connections

Wed Mar 26 06:42:00 2003

Hi Daniel and all,

Mind that the AUDIO OUT from the J5 Aux. AF on the RF Board is balanced audio between pins 1 and 3 and you will
need to buffer it and convert it to unbalanced audio (that's what my DI PCB does through the LM386N circuit) so
you'll need an additional pin. I still think that the best bet is to follow Sverre Holm's, LA3ZA, idea and take the
AUDIO OUT from the VOL2 terminal of R3 on the very same Front Panel board, very close to the Mic Configuration
Header, and jumper it to pin 8 of the mic's connector. (You can take pin's 8 jumper block off as it is a dup GND
connection of pin 7 and keep the remaining blocks on).

By doing this mod you'll have to modify your MH-2 connector's connections too, as it uses pins' 7 and 8 to ground
the mike. Just desolder the cable from pin 8 and solder it to pin 7, together with the shielding braid. At the same
time I have also desoldered the 5.6K resistor I had installed between pins 1 and 6 at the rear of the microphone
connector on the Panel Control Board and have installed it within the MH-2 connector, between pins 1 and 6, of
course.

Now at pin 8 I have an unbalanced fixed level AUDIO OUT connection. Have tried buffering that AF OUT using a BC107
transistor, but I like better the use of an LM386. I use the 5 VDC present at pin 6 to feed the circuit on a
proto-board and it works fb.

Best 73

Pauli, EA3BLQ
K2 # 1044/100
URL: http://www.qsl.net/ea3blq/
[email protected]
[email protected]

On Wednesday, March 26, 2003 4:08 AM "Daniel L Brinneman" <[email protected]> wote:

: Hi,
:
: would it be wise for me to connect 12VDC and AUDIO OUT from J5 on the RF
: board to the Front Panel mic connector on the unused pins?
:
: The unused pins being UP and DWN,  I would take the jumper block off of
: these pins and put a label next to it for future reference.  I have the
: MH-2 in use.  will these voltages and audio out effect the microphone?
: Does the mic, MH-2,  have any connections on the UP and DWN pins holes?
:
: Daniel
: kg4dni