[Elecraft] Fixed level audio output for K2

Wed Jan 29 11:39:25 2003

I have just completed a 10x amplifier (using one half of an LM358) that
I intend to put between the top of the audio pot and the output. The
original direct output suffers from too low level to drive a PC
soundcard sometimes, and also if the shielding/grounding is not good
enough, it will pass hum back into the K2. 

The amplifier is completed and tested, but not yet installed in the K2.
It is tiny and can be glued to the back of the front panel board. Why is
it so tiny? Well, it was made mostly with surface mount components. 

It is possible to use the other half of the LM358 as a mixer with one
input for the sidetone, one for the microphone and one for the normal
audio. I won't do that intially, as it means routing wires from board to
board, but I may put the sidetone in there eventually.

Sverre
LA3ZA

> -----Original Message-----
> From: [email protected] 
> [mailto:[email protected]] On Behalf Of Pauli 
> Nunez EA3BLQ
> Sent: 27. januar 2003 19:04
> 
> I quite recently made the AF Gain Control Mod to my K2, and 
> following the idea posted to the reflector by Sverre Holm, 
> LA3ZA, now I also have a low level fixed audio output on pin 
> 8 of my mic connector. I put a jumper between pin 8 of the 
> mic configuration head, at the Front Panel board, to the VOL 
> 2 terminal of R3 on the same Front Panel board. I would like 
> to remember that Sverre installed a 1k resistor between those 
> two points. The level is fixed and quite low but you can 
> always amplify it if needed.