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eHam Forums / Elmers / RE: Stray RF
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on: July 13, 2012, 01:20:58 PM
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Thanks to everyone who replied to my post, thank you for everything. I think we can close this post now.  Blessings Joseph, KF7LPU 73s |
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eHam Forums / Elmers / RE: Stray RF
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on: July 12, 2012, 10:23:06 AM
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The 4 to 1 balun at the antenna feedpoint should be a current mode balun, NOT an un-un and NOT a voltage mode balun. Those do nothing for common mode currents. Do you have a commercial OCF? Which one? There is one manufacturer of OCFs that uses a voltage mode balun and apparently allows feedline currents on purpose. That would be the worst one to use. I would recommend replacing the balun on that antenna.
Jerry, K4SAV
I built my own OCP dipole using the design from the following website. http://www.packetradio.com/catalog/index.php?main_page=index&cPath=49&zenid=fdjs0fq1hqrki5vseqr29mr114Joseph, KF7LPU |
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eHam Forums / Elmers / RE: Stray RF
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on: July 12, 2012, 10:18:47 AM
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Explain your balun--if it's a choke balun (unun), that's good; but if its a voltage or current balun, then it shouldn't be used with an off-center fed antenna. A choke unun will keep (most of) the common mode currents off the coax so that only the antenna radiates.
The other suggestions are valid; you probably could use chokes on the WiFi Cat5, speaker, and touch lamp cords to minimize stray RF. (Touch lamps are especially sensitive to oddball RF and static problems). Radio Shack and other outlets sell clamp-on chokes (RS273-104 is their best, at around $10 each, and is what I'd recommend for the speaker cables; but 273-105, 273-069 and 273-067 are possible substitutes). GL in solving the problem.
I have a current balun at the top where the wires legs hook in, but a choke balun "ugly balun" near the shack. Joseph |
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eHam Forums / Elmers / RE: Stray RF
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on: July 12, 2012, 10:13:02 AM
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(probably exacerbated by the OCF dipole, improperly choked, but that's another subject).
73, K8AC
Can you tell me a little more about this topic. Joseph |
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eHam Forums / Elmers / Stray RF
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on: July 11, 2012, 11:01:24 PM
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Over the last two weeks I have been messing with my FT-107m to address some SWR issues. I noticed tonight that when I transmitted I was getting stray RF. The touch lamps were turning on and off, the wireless internet went out, and my signal was heard through my home stereo speakers. Like I mentioned earlier, I am using an FT-107m with matching power supply, Vectronics VC-300M tuner, RG-8 running to a new OCF dipole. The dipole's balun is 40 - 50 ft off the ground, and the legs run over the house. The roof does have a tin roof, now I don't know if that is the problem, but I sure could use a second opinion as to what may be the case for the RF issues. Any help would be helpful, I am still learning how to properly setup a station.
Joseph
KF7LPU
73s
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eHam Forums / Amplifiers / RE: Swan Mark I
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on: November 05, 2011, 04:30:41 PM
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We check input and output voltage to the tubes for its 5 volts, and the current is constant to the plates. The tubes both light, and the tube schematic shows the pins to check for shorts across the tube. There is high voltage applied the plates. K1 reley closes to complete the keying circuit correctly.
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eHam Forums / Amplifiers / RE: Swan Mark I
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on: November 05, 2011, 04:26:34 PM
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K1 is working when in transmit, when set in EP it shows 800 watts to the meter, and in IP 0. The SWR running in was less then 1.5. As well when set to output their is 0 to the meter. I remember the night it started to mess up. I have a TS-450S with the tuner, that I used to bring the SWR down, and I think it created a mismatch and ever since the amp has not worked the same.
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eHam Forums / Amplifiers / Swan Mark I
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on: November 05, 2011, 02:48:43 PM
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Over the the last couple of months I have been struggling with my amplifier to put out. I check over all the components that would give me trouble and all checks out good. The tubes and tube housings are good, but for some reason when I hook everything up, I flip to a band and hit transmit to tune the meter, it shows zero output. The meter won't budge at all, and I am super confused; because it was working perfectly without problems. Can anyone who has dwelt with or had similar problems help me.
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eHam Forums / Antennas and Towers and more / Long Wire antenna
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on: October 27, 2011, 11:53:11 PM
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I am familiar with building inverted V style dipoles, fed with latter line; but I have never built a long wire antenna. I have heard that this dipole wire antenna is not center fed, but is just a wire straight from the radio coax. Can someone help me clear this up and help me understand how to built one.
Joseph
KF7LPU
73
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eHam Forums / Elmers / Understanding Propagation
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on: October 27, 2011, 11:25:34 PM
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I have over that last several months been trying to wrap my mind around propagation, and how it works. I was hoping someone could explain how the sun effects the layers in the ionosphere. How the gray-line effects propagation, and where to point your beam during the day. I was hoping someone could explain how the radio waves are absorbed during the day and night. I was on 20 meters in the evening and it seemed like no one was on the band. The same with 40 meters, with their something special about nighttime verses the day. Any help would be great.
Joseph
KF7LPU
73
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