Saturday, May 06, 2006
I've been fighting radio frequency noise issues for some time.
I've already hunted down the two biggest culprits, a battery charger (heard from 1/4-1/2 mile away) and a light dimmer switch.
That's taken the noise from 20 to 40 dB over S9 down to "just S9."
In a concerted effort this afternoon I also located a treadmill as a significant source of noise. Leaving me a significant dilemma...
I've still got hum.
If I put an AM radio near any of the three antennas' coax, I get significant hum.
If I run the radio off of battery and disconnect the earth ground the hum mostly goes away. (The entire system is floating at that point). As soon as I connect the "black" lead back to a power supply, or reconnect the earth ground, the hum comes back.
Now given the "construction techniques" used in this house, I wouldn't rule out hum on the house ground. But JV and I pounded in 4 eight-foot copper rods into my front yard. They are connected together with two pieces of 6? or 8? gauge copper wire, one of which continues into the shack. I believe the "earth ground" is about as good as you're going to get in these mountains without the addition of chemicals to the soil or a pond (hmmm... two hobbies with one project... gotta remember that one.)
I'm guessing that I'm getting AC hum into the system someplace(s) and when it sees a path to ground (either house or earth) it makes itself known.
With everything unplugged and the system floating, the 40m band is glitteringly alive with signals. I don't normally hear that (contest or not). It normally sounds sort of muted or muffled.
HELP?!?
Rig: Icom IC-706MkIIg.
Power: Astron 30A and 88 A-hr battery in parallel through a PowerGate
Antennas: HF #1 G5RV Jr, HF #2 ~170' circumference vertical loop, VHF/UHF Diamond D130 Discone, VHF packet, dual-band j-pole.
I've already hunted down the two biggest culprits, a battery charger (heard from 1/4-1/2 mile away) and a light dimmer switch.
That's taken the noise from 20 to 40 dB over S9 down to "just S9."
In a concerted effort this afternoon I also located a treadmill as a significant source of noise. Leaving me a significant dilemma...
I've still got hum.
If I put an AM radio near any of the three antennas' coax, I get significant hum.
If I run the radio off of battery and disconnect the earth ground the hum mostly goes away. (The entire system is floating at that point). As soon as I connect the "black" lead back to a power supply, or reconnect the earth ground, the hum comes back.
Now given the "construction techniques" used in this house, I wouldn't rule out hum on the house ground. But JV and I pounded in 4 eight-foot copper rods into my front yard. They are connected together with two pieces of 6? or 8? gauge copper wire, one of which continues into the shack. I believe the "earth ground" is about as good as you're going to get in these mountains without the addition of chemicals to the soil or a pond (hmmm... two hobbies with one project... gotta remember that one.)
I'm guessing that I'm getting AC hum into the system someplace(s) and when it sees a path to ground (either house or earth) it makes itself known.
With everything unplugged and the system floating, the 40m band is glitteringly alive with signals. I don't normally hear that (contest or not). It normally sounds sort of muted or muffled.
HELP?!?
Rig: Icom IC-706MkIIg.
Power: Astron 30A and 88 A-hr battery in parallel through a PowerGate
Antennas: HF #1 G5RV Jr, HF #2 ~170' circumference vertical loop, VHF/UHF Diamond D130 Discone, VHF packet, dual-band j-pole.
