On 9/7/2012 6:58 AM, ULLS wrote:
I am trying to receive an am signal well below ground level in a metal
server room, there is a coax feed up to the roof which I used and
attached the standard wire loop that was supplied with the tuner,
however when I attempted to tune into some stations I could only pick up
a couple of local stations and wasn't able to receive the ones I was
hoping for. when I dialed in the desired frequencies, all I was
receiving was a tone, the tone changed in frequency/pitch depending on
the tuners frequency. To check that I could receive the stations I took
the tuner to the roof and attached the antenna directly and sure enough
I could pick up the desired stations. My thoughts are that the coax is
affecting the signal in some way, perhaps picking up electrical noise?
any advise would be appreciated.




I am sure you are too young to remember placing an AM radio on top of a
CPU and running certain programs to produce music. Waltzing Matilda was
one. I recall my 2 meter FM mobile rig, driving up to the building,
hearing the noise from 20 ma. current loop to terminals. You are in the
middle of a vast sea of digital noise! All your AC power wiring is
conducting it everywhere.

I am not surprised at you hearing tones.

First, you need to have a battery powered radio so the AC wiring is a
little further away from the receiver.

Second, you might want to try RG-6 coax. It's cheap and as I recall,
double shielded. You will want to find a place to ground one end, only,
of the coax to a building ground, not an AC outlet ground wire.

How close is your current coax to other signal carrying cables? Keep the
coax as far away as possible. Never running parallel, if possible. And
if crossing, cross at right angles.

Finally, does anyone else working there have a radio that is receiving
properly?

IF nothing else will work, there is always FM.

Paul, KD7HB