Tube PHONO preamp interference - RFI, EMI, bad grounding?

There's a 33ohm resistor on the grounding cable between the chassis and the inlet.

@filipm Unfortunately, I don't have the engineering and design knowledge that's required to explain why that's in the circuit. Looking at the resistor, at this point in time, if you wanted to re-insert it back into the circuit, it's going to be impossible to do that, with the lead now clipped right at the resistor. I'm not sure I would have removed it, as you say the EAR plays fine anywhere else you use it, besides when used with *your* system. That means you have a problem that's exclusive to *just your* setup.  

That photo showing a 33 ohm resistor partially encased in yellow shrink wrap looks like very amateurish work. Could be the ill advised work of a previous owner. Also, is that resistor connected at its other end? If not, it’s not doing a blessed thing.

You never mentioned whether tightening the transformer laminations, etc, had a beneficial effect on noise emanating from the chassis (not the noise that we started out talking about which contaminates your audio signal).

At this point you’re  receiving a lot of advice of questionable merit, apart from posts by Atma-sphere. If you don’t have or can’t access local expert help, I suggest you pay attention to Atma.

@filipm thanks for posting those pics. Very interesting..yes, if you want to put it back together the way it was you may need a new 33 ohm resistor, but those are cheap enough. That one looks like a Vishay-Dale metal film, which are often found in audio because of how quiet they are.

I searched the web for images of the EAR 834p to see if I could find some that did not have the resistor, but of the ones that I found were a good enough pic to see the wiring in this spot of the EAR - all had the resistor there. So it seems intentional.

This one appears to have the same resistor as yours..(you may have to click the plus sign cursor once to increase its size)

This one does as well.

This one is a great pic, with what appears to be a "standard" (cheaper) metal film resistor between the ground post inlet and the IEC ground, and appears to be connected to the PCB ground plane directly (which would then match your EAR if I read things correctly).

Look at the first one again though at the RCA input jacks - there is some component they have bypassing signal to ground - a capacitor perhaps for noise filtering? Showing my inexperience here, I have not seen a capacitor that looks like that, perhaps one of the more expert folks on the thread can tell us what it is. Likely a custom mod (especially considering the Hovland MusiCap capacitors in there that I am reasonably sure are not stock given their cost).

I live near a major Air Force Base and occasionally get interference (although mostly on FM) from one of the radars on the base.  The periodicity of the noise to me is a giveaway that it is something causing a "sweep".  What that might be you are better to guess than me.