[Elecraft] K2/100 - Softening the un-mute POP on SSB

[Bill Coleman]

On 10/28/02 10:21 PM, Bill Coleman at aa4lr@arrl.net wrote:

>After using the K2/100 this weekend in the CQWW Phone contest, there's 
>one quality that really could use some polish.
>
>My K2 tends to give a pop or a snap when unmuting in SSB. Not every time, 
>but frequently. I don't notice this on CW. It's a pretty loud pop, and 
>when you are wearing a headset, it can be a bit painful. I'm worried that 
>this can cause hearing fatigue, or possibly hearing damage over the long 
>term.

Sorry to respond to my own message, but others may want to know what I 
discovered.

In this case, I was using the headphones through an external headphone 
junction box plugged into the speaker jack. 

This turned out to be part of the problem. If you examine the K2 
schematic, you'll find that he headphone jack has series resistors and 
shunt capacitors. These act as a low-pass filter and attenuate the pops I 
encountered.

I also had an AUXBUS problem, which I later fixed (a bit of flux was 
pulling this line up to almost 7 volts). This could have contributed to 
the extra pops when pressing multi-chip functions.

Bottom line: Use the headphone jack for headphones.



Bill Coleman, AA4LR, PP-ASEL        Mail: aa4lr@arrl.net
Quote: "Not within a thousand years will man ever fly!"
            -- Wilbur Wright, 1901