ckmcdonald
Member
- Joined
- Dec 21, 2016
- Messages
- 29
Need some help...
I have been fighting RF in the shack for several months now. I have ruled out the radio, amp, feed line and very likely my grounding scheme. I'm running an 80m straight (not inverted) OCF dipole 28' off the ground. I have a "factory" provided voltage balun and a "factory" provided 600-1000 ohm choke directly below the balun. "Factory" meaning purchased, and with a lot of other customers using this same setup without problem. I have 75' of LMR-400UF between the choke and the radio.
I'm getting enough RF in the shack that my mic is shocking me. Noticeably warms my skin at 100W (barefoot) and shocks me pretty bad at 500W (amp). At 400W-500W out I have fried several electronic devices in the shack - fortunately nothing very expensive and all were sitting within 2-3 feet of the radio gear. It does it on at least 2-3 bands, most notably around 7.2MHz. The raw SWR of the dipole at this frequency is 1.3:1.
The short leg of the OCF dipole hangs directly overhead the shack 21 feet above the radio gear.
If my calculations are correct the distance to the antenna is well within the MPE limits. I'm too inexperience to have a feel whether this much radiation can be expected from a dipole at that distance.
I can't determine if the radiation is getting in the shack on the feed line (the choke is supposed to prevent that) or getting in through the air from the antenna (or some other way). The radio (and amp) is connected only to a battery (no AC connection).
All equipment is grounded with 8 feet of 6 AWG copper wire to a 6 foot copper ground rod (all installed new less than 4 months ago).
Can I get comments please on if my antenna is too close to the shack, or if this is feed-line RF?
Thanks
I have been fighting RF in the shack for several months now. I have ruled out the radio, amp, feed line and very likely my grounding scheme. I'm running an 80m straight (not inverted) OCF dipole 28' off the ground. I have a "factory" provided voltage balun and a "factory" provided 600-1000 ohm choke directly below the balun. "Factory" meaning purchased, and with a lot of other customers using this same setup without problem. I have 75' of LMR-400UF between the choke and the radio.
I'm getting enough RF in the shack that my mic is shocking me. Noticeably warms my skin at 100W (barefoot) and shocks me pretty bad at 500W (amp). At 400W-500W out I have fried several electronic devices in the shack - fortunately nothing very expensive and all were sitting within 2-3 feet of the radio gear. It does it on at least 2-3 bands, most notably around 7.2MHz. The raw SWR of the dipole at this frequency is 1.3:1.
The short leg of the OCF dipole hangs directly overhead the shack 21 feet above the radio gear.
If my calculations are correct the distance to the antenna is well within the MPE limits. I'm too inexperience to have a feel whether this much radiation can be expected from a dipole at that distance.
I can't determine if the radiation is getting in the shack on the feed line (the choke is supposed to prevent that) or getting in through the air from the antenna (or some other way). The radio (and amp) is connected only to a battery (no AC connection).
All equipment is grounded with 8 feet of 6 AWG copper wire to a 6 foot copper ground rod (all installed new less than 4 months ago).
Can I get comments please on if my antenna is too close to the shack, or if this is feed-line RF?
Thanks