HFU HF Underground
Technical Topics => Equipment => Topic started by: Capt. Kidd on July 23, 2017, 0144 UTC
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Does anyone have any dipole designs they know work? I've got 50 watts running through 25 feet of cable to an inverted v shaped dipole coming from my attic window on 6915 kHz and I can't seem to get anything on the online sdr. Any ideas?
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I dare you to find a antenna more efficient than the good old dipole.
I'd add some ferrites to each end of the coax, make sure that coax is in good condition, and make sure there's nothing near the antenna that can detune it. Also look into "cobra" dipoles, they add linear loading to the mix and can be of benefit. Also consider propagation, if you don't have it, you're not going to get out.
http://www.kb6nu.com/yet-another-new-antenna-the-cobra/
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Dipole designs??
There's only one AFAIK!
What vswr do you have?
Str.
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Maybe the problem isn't the transmitter or the antenna, perhaps it's the online SDR?
Have you taken a portable SW radio out and about to monitor the transmission?
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Antenna placement; is the antenna on the side of the home or signals being blocked by a nearby neighbor. Had a instance in stucco clad home which used a wire mesh sub-base made a effective Faraday cage blocking and/or reflecting signals. Once the antenna elevation was increased above the sidewalls of the home it corrected the issue. Didn't note whether you indicated any noise issues, could incoming signals be buried in the background?
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I used to live in a very old house and the house wiring had this steel cover that often resonated to any dipole I placed in that attic... but that is quite another story.
Propagation has a lot to do with it... The SDR could be too close or too near depends on time of day etc... And remote SDR's don't always receive in the direction you might want to hear...
As mentioned by another try using your own receiver (portable I hope) outside of the building if the signal is weak there then check your coax and your coaxial connectors... If that fails check the transmitter into a dummy load to see if it is, in deed, really putting out any real RF. BTW I have known new coax (with connectors) to not be soldered correctly or at all... ahhhhuuuummm does happen not often but.
Don't mind me... just covering areas others have already done did dood dude!
BTW... my question is this... Is this transmitter a solid state wide band type of rig or do you have to tune the thing up as in older tube type gear... Just showing my age....
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Here's a quick way to utilize those online SDR's this time of year. 20 UTC to 0:00 UTC, in that frequency range, use one 300-500 miles from you. 1:00 UTC on look for ones 500-800 miles away and further as the night progresses.
And get the peak of that antenna above the roof line if possible. Wire mesh, rebar, aluminum siding, and metal roofing are RF eaters, not to mention wire and chain link fences, though the latter can make a dandy ground plane for a wire vertical going up into a tall tree.
Of course, this all for informational purposes only.
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I've always found that a Magnetic Monopole antenna is a good performer.
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Will ask again....
WHAT SWR DO YOU HAVE?????
;)
Str.
p.s. waiting for answer........ ???