[Elecraft] WSJT-X K3/K3s hanging as Tx

[Richard Lamont]

On 13/11/17 20:18, Jim Brown wrote:
> On 11/13/2017 11:12 AM, Gary Smith wrote:
>> For those using WSJT-X, sometimes I find
>> the K3s is locked as transmit but there is
>> no RF being sent and no Rx from the K3.
> 
> I've been using WSJT-X since it was first introduced several years ago,
> and I've never had this problem. I've always used VOX to put the rig in
> TX mode, as I do with SSB and all digital modes. I've often run with a
> power amp that uses a vacuum relay for T/R switching, and there's
> sufficient delay within the K3 and K3s for the amp's T/R relay to switch.

You may be putting the performance of your station at a disadvantage
with that approach, compared to using WSJT-X with CAT to keep TX audio
in the range 1500-2000 Hz.

The roofing filter may have a fair amount of group delay inequality at
the edges of the passband, which can lead to inter-symbol interference
on digital modes. I don't know how serious, if at all, this is in
practice, but I know one very clever engineer who regards it as enough
of a problem to have had a custom roofing filter manufactured for his K3
to reduce it. He mainly works EME with JT65.


73,
Richard G4DYA