In article ,
KC8QJP wrote:

cut the ground off the blanket that will make the hum go away

That strikes me as very poor advice, for three reasons:

[1] I've never seen an electric blanket or bed-heating pad here in the
U.S. which *has* a ground prong. They all use two-wire
(hot/neutral) plugs.

[2] If there *is* a ground prong on a device which is used in close
proximity to a human body, it's probably there for a very good
reason (safety). Removing a safety ground from such a device
seems like a really bad idea.

[3] If the reason for the humming is a harmonic-currents problem (as I
suspect) then it has *nothing* to do with the presence or absence
of a ground connection. It's due to irregular current flows on
the hot and neutral wires. Floating the device free from the
safety ground will have not reduce the problem at all.

"Floating" an equipment-chassis ground can sometimes help reduce hum
in audio/video equipment if the hum is due to a ground loop. I don't
believe that ground loops have anything at all to do with the original
poster's buzzing-transformer problem.

--
Dave Platt AE6EO
Friends of Jade Warrior home page: http://www.radagast.org/jade-warrior
I do _not_ wish to receive unsolicited commercial email, and I will
boycott any company which has the gall to send me such ads!

DP [1] I've never seen an electric blanket or bed-heating pad here in
DP the U.S. which *has* a ground prong.
No ground prong on my blanket or frying pan.
Thick house wiring all done by myself, so that can't be the problem
(don't tell Mom about the day I made a loop and all the conduits in
the walls shook.)
Therefore I shall, as a nod to the less privileged who perhaps don't
even have electric power, learn not to eat or sleep while using the
computer or my radio equipment (BM4IFV, not on air anymore, now just
on email). OK, thanks. Bye.