[Elecraft] Making a Signalink cable for the K3's 8-pin mic connector

[Jim Brown]

On 5/9/2014 4:40 PM, Slava Baytalskiy wrote:
> By "my audio stuff" i mean a mic.
> I'm using a Shure SM58, into a mic preamp, into a gate/compressor/limiter/de-esser into an EQ into a mixer into the K3's line-in.

Hi Slava,

A de-esser works in the 6-8 kHz range, and you need it in a studio, 
especially with mics like the SM58 that are sibilant, it's totally 
useless for ham radio. If you want to use an SM58, you can run it 
straight into the front panel mic input with a suitable adapter -- pin 2 
of the XLR is hot, pin 3 and pin 1 get tied together and go to the 
connector shell. The K3 has excellent EQ and compression built in, so 
you've got a lot of stuff there that you don't need.

The SM58 is an singer's vocal mic, it has proximity effect, which adds a 
lot of bass that must be equalized out. Pro mics are overkill for ham 
radio (in terms of cost), but if you want to use one, go for one of the 
EV variable-D mics -- RE10, 11, 15, 16, 18. No proximity effect, no 
sibilance.

Another issue with trying to use a pro mic in ham radio is that ham mics 
have presence peaks around 3 kHz to compensate for the rolloff of the 
crystal filter, so you must add that with an equalizer. The TXEQ in the 
K3 works VERY well for that.  Before W6XU turned me onto the Yahama 
CM500 headset, I was using an RE16 from my stash of recording mics, on 
an AKG boom. Worked fine, I got great reports, but the CM500 is $60, and 
sounds great too.

> So line-in is taken. I can't put a Y cable there because, correct me if i'm wrong, every time Signalink would key up - the mic would go live.
> So that's not an option for me.
> I think its a lot easier to just hit a couple of buttons and switch to the front panel mic for digital work, isn't it?
> And the rear mic won't go live either.
>
> As far as audio interface goes, yes, i have an E-mu 0404 USB that i can use. But signalink works just fine. No drivers to install. And it has just enough controls.
If you're happy with it, use the Line In. But remember that it has a Pin 
One Problem, so you could run into RFI with it.

> I really don't see why i would need a studio quality sound card for PSK31.

See my exchange with N7WS about that in this thread -- a better sound 
card can improve linearity at the bottom of the dynamic range. In fact, 
you need a decent USB sound card a LOT more than all that outboard gear. 
The 0404 is overkill, although nice if you want to feed a spectrum 
display using NaP3. The Signal Link may be good enough -- the cheap 
Numark and somewhat nicer Tascam certainly are.

I use the CM500 plugged into the rear panel mic and headphone jacks, 
assign the "Headphones + Speaker" toggle to one of the PF keys. That 
lets you use the K3's excellent audio processing, get rid of all that 
outboard gear, and makes it very easy to switch from SSB to digital modes.

73, Jim K9YC
Retired audio professional