[Elecraft] SignalLink USB

[Don Wilhelm]

The "solution" is to run the SignaLink soundcard levels at a lower 
output level so you do not encounter distortion.
With that being done, the SignaLink will likely not produce its PTT 
output reliably.

With the K3, use VOX to initiate transmit rather than the SignaLink PTT 
- it will work just fine provided you set the VOX gain level correctly.

For those who have doubts about my 'solution', consider that the 
SignaLink uses the audio level to determine whether to activate its PTT 
output.  That is nothing more than a simplified VOX.  The K3 VOX is much 
better at detecting a particular audio level and activating transmit 
than the SignaLink because the K3 VOX level is adjustable. So ignore the 
SignaLink PTT output and use the K3 VOX instead to initiate transmit - 
it will work much better.

The alternative is to use the data mode software to put the K3 into 
transmit rather than depending on the SignaLink PTT output.  Most data 
mode applications have the capability to put the K3 into transmit via an 
RS-232 command if you set the software up to do that.

In other words, do not fight the SignaLink limitations, use it as an 
external soundcard only and ignore its other functions.
BUT then, a better quality external soundcard can be had at less than 
half the price of a SignaLink and will do a better job.

Yes, the SignaLink with its cables specific for the radio you have makes 
it easy for a beginner to get started, but that simplicity has its 
limitations, and those limitations have already been expressed in this 
thread.

73,
Don W3FPR


On 7/4/2015 7:40 PM, Joe Subich, W4TV wrote:
>
>
> In general the modifications documented on the several web pages
> are sufficient.  However, improving the power supply bypassing
> and decoupling noise sources will also help the noise floor.
>
> The big problem that none of the modifications address is the need
> to run the Windows (digital) output at 100% in order for the VOX
> to trigger properly.  Unfortunately, the PCM29xx series USB CODEC
> gets a little dirty at max output and with the unstable reference
> to the op amps, the transmit distortion is only compounded *before*
> the TX level control.
>
> 73,
>
>   ... Joe, W4TV
>