I get that carrier frequently on 6938 kHz, late nights through early mornings, usually S2-S3 out of 5, sometimes stronger. I got a partial CW ID off it once, which would make it an HFT transmitter.
The CW ID I heard was W_3XPX, probably the missing (faded) character was an X, as these HFT transmitters (at least I think this one is HFT) are technically 'experimental' licensed stations.
[EDIT: it if were licensed with calls similar to the other HFT stations we know about, it would be a WP____ not WX_____. Being that I didn't hear the second character clear enough to decode it, I have no idea what that second character was.]
No idea where this transmitter is located, but the Digital Racket Maker on 6838 I think is in the Midwest, from at least one morning checking out the different online SDR's.
As for 6938, I've never heard the horrid digital racket off this station that I've heard on 6838 kHz and a few others across the spectrum (digital noise, with the pulses sped up drastically right before it shuts off -- 1-2 seconds of silence -- then it starts up all over again).
Mostly I hear weak to moderate carriers.
I'm in western WA state, and my radios are mostly a PL-330, D808, DX-394, and sometimes a couple others, into a 35 ft indoor wire and 90 ft outdoor wire.