Slight background tone or hum on transmit?

I tested my RT-524 yesterday on 52.25Mhz with the owner of my local NAPA store who has a radio in his Jeep. We didnt have time to set up a long distance test so he was on one side of the building and I was only about 200 feet away on the other side of the building in a downtown location. Just wanted to check to see if mine was working. Worked fine, but he said there was an audible tone or hum when receiving. Not too loud, but nevertheless there. Question is, is there always such a noise with these radios, or should there be no audible background noise? My engine was off, so there was no chance of alt. interference or such. Other than that, it was very clear and nice.
Thanks for any input,
BC

Congrats, you fired it up! I'm no expert on these radios by any means BC, and I've only used mine a couple times, but I get no background noise. Crystal clear and sharp, transmitting and receiving.
I'm sure there are many factors that could cause distortion though, so maybe some of the experts will know.
Love your avatar btw.

Thanks Paul,
There is a power company sub station about 200 yds from where we were and I have since been told that it raises havoc with HF in the area. I really need to set up a better test. But, at least I know it works
BC