[Elecraft] XLR on K2

[Jim Brown]

On 3/9/2022 2:31 PM, gt-i at gmx.net wrote:
> However, it would be good to know if your mic needs extra supply voltage
> ("phantom") or not. If your mic is a cheap one, than it is probably no
> condenser mic and doesn't need it.
> Note the K2 can supply +5V on the MIC connector, while the phantom
> voltage is 48V.

Phantom power ranges from about 12V to 48V, depending on the mic. 
Professional mics that require phantom power are NOT compatible with the 
unbalanced inputs that are used on all ham gear I'm aware of. The ONLY 
way they could be used is with a dedicated phantom power supply followed 
by a suitable audio transformer between the PSU and the rig.

Professional DYNAMIC mics ARE compatible with virtually all ham mic 
inputs, requiring nothing more than a properly wired cable adapter. Pin 
2 of the XLR goes to Mic In, Pin 3 goes to Mic Return, Pin 1 goes to the 
shielding enclosure (chassis). Bias should be turned off.

Pro mics are, however, serious overkill for ham radio. "A fool and his 
money . . . ."   But if it's free, why not? :)

I'm speaking as a retired audio professional, ham for 66 years.

A stock K2, unfortunately, is not a great SSB rig, for several reasons. 
First, the audio chain lacks enough gain to activate the limiter enough 
to matter, needs low end rolloff. Second, while the RX sounds very good 
on SSB at full bandwidth (where it uses the TX SSB filter), when the RX 
crystal filter is re-aligned for narrower bandwidth, the response is 
VERY peaky, creating so much phase distortion that it makes speech more 
difficult to understand.

This is not surprising -- it started out life as a QRP CW rig, so adding 
SSB was a compromise.

73, Jim K9YC