On Tue,3/7/2017 5:30 AM, Timothy Holmes wrote:
1. It seems that I have some issues with RF in the shack – Im running a 3
element tribander at 35 feet (practically directly over head of the shack)
and a 125 foot dipole fed with just north of 31 feet of ladderline
(technically its window line bought from AES before they closed – the stuff
in the brown plastic insulation with windows in the line). There is a LDG
4:1 Balun fed by about 20 feet or so of coax that feeds the window line,
and the balun is connected to my LDG AT200Pro Autotuner. My Rig is an
IC706mkIIG running barefoot at 100w.
Hi Tim,
Antennas close to the shack DO put RF in the shack if they're working.
:) The feedline to that dipole will carry common mode current from the
antenna to the shack unless there's a good common mode choke at the
feedpoint. It's not practical to choke 2-wire transmission line like
you're using. The feedpoint Z of a low 125 ft dipole is close to 50 ohms
on 75M, making it a good match to coax, and low impedance feedlines that
are matched to the antenna CAN be choked. See k9yc.com/RFI-Ham.pdf
That 2-wire line you bought is not a good thing for most ham stations,
because it cannot be choked. Without a good choke, RF couples to the
shack and noise picked up on the line couples to the antenna and from
there back down the line to your receiver. That noise coupling is a BIG
problem, because we're surrounded by RF noise sources.
The symptoms that I am having are as follows:
on some frequencies waveyness on the LCD computer monitor
the 706 does not like to operate with the front panel extension cable in
place, it shuts down when I key up
That's not surprising. The 706 is a super-cheap rig, and the front panel
extension cable makes a great receiving antenna to couple RF into the
radio.
occasionally, the tuner will show a reading event though I am using the
Tribander
Also not surprising if it's connected to the dipole and the dipole is
close to the tri-bander. The dipole is picking up the RF radiated by the
tribander and sending it down the feedline to the tuner. That's how
antennas work! I suggest that you don't use the extension cable.
My Father’s computer speakers at the other end of the house relay my
signals QUITE efficiently
Computer speakers are notorious for picking up RF. If they're picking up
RF, they are junk. Toss them in the trash.
the touch lamp in the living room goes nuts when I transmit.
This is a common problem with touch lamps. Their detection circuitry is
high impedance, and probably not filtered for RF. Again, badly designed.
Throw them in the trash or unplug them when you're transmitting.
Im not really sure what other information you may need to help me
troubleshoot and solve these problems, but I would appreciate any help I
can get. Hamvention is coming up, so if I need some parts, I might be able
to get them there, also, DX Engineering is just down the road, and I am
ALWAYS happy for an excuse to go there HI, HI.
If you have money to spend, I'd suggest a better radio. Get the advice
of experienced contesters to chose a good used radio like a TS850 or an
Elecraft K2/100. And whether you spend money or not, work on good
grounding and bonding for your station. It won't help the computer
speakers or the lights, but it can help with issues in your shack.
Study http://k9yc.com/GroundingAndAudio.pdf
73, Jim K9YC
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