Well, I have had the radio issue. I built the amp I had the problem with and what ended up happening was I put a 10K resistor between the first preamp tube and the input wire from the jack. It added a speed bump that the radio signal could not over come. Remember that at the very start of the chain any little noise gets amplified quite a bit, so seemingly insignificant noises become, uh, interesting.
The whistling that I had with my amp was an incorrect wiring. It created a ground loop, and the noise that is filtered off by the electrolytics was seeping back into the signal chain. It whistled, howled, sort of delayed, and sounded a lot like feedback. Imagine that, a signal that was feeding back into the signal chain sounded like feedback... If it is a new amp, this obviously should not be happening. But, you might take some time, and a shop vac, and vacuum up any dust/debris that might have gotten into the amp from shipping before giving up. There might be an oddball chance something is causing a circuit bending short that makes the noise. Tube amps are finicky but when they get comfy they really do sound incredible.
Patrick