Can anyone identify this QRM?

[Stronty]

Do another screenshot showing 26mhz, is the interference present down there? Maybe post a video/audio file so we can hear what it sounds like.
[/quote]

Yep can see what you're getting at, seems to be an edge of some crap just below around 27.00. Sound clip could be very telling as you say.

[Ripshod]

This cheap SDR receiver is going in the bin. It seems to be throwing out it's own QRM. Let me show you this:

SDR11WTF.jpg

It does move with the frequency as I move the tuning scale, but at only half the rate. So If I move the frequency scale say 200kHz, this noise band will only move ~100kHz. Although I can still definitely hear a mains frequency buzz on AM all over the 11m band.
I have a decent sdr arriving sometime tomorrow so I'll redo all the screenshots. Maybe we'll get to an answer then. Thanks for your thoughts so far everyone.

[delboyonline]

Basically if the interference is present below and above the standard 40 channels CB band (26.965 - 27.405) but not actually on the CB band is very likely to be PLT.

[Ripshod]

Basically if the interference is present below and above the standard 40 channels CB band (26.965 - 27.405) but not actually on the CB band is very likely to be PLT.

That would make sense, only the noise floor is high from below the 12m band and well into the 10m band.
My new sdr is the nesdr smart v5 from nooelec. I've had a little look and I'm impressed so I'll do some investigating today.

[Ripshod]

Okay. So this is what I see today on the portion of the band I actually use:

MyBand.jpg

Make of that what you will. I have set the gain to reflect what I see on my radios' meters.

I've gone right down into and past the 12m and 15m bands and the noise is still there, but no sign of a signal strong enough to cause this.
I guess I'll just have to accept that it's just what it is in my area.
Point to note: I'm well within visual range of the Emley Moor transmitter.

[Transwarp]

There's so much RF noise generating stuff today that HF is a lost cause if you reside urban imo. Semi rural helps, fully rural with no commercial communication masts / transmitters nearby - with a decent height above sea level - is a dream for radio hobbyists.