HFU HF Underground
Technical Topics => Equipment => Topic started by: ultravista on February 20, 2020, 2017 UTC
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I bought a 2nd-hand Pixel RF-PRO-1B antenna and unimpressed thus far when comparing it to a PA0RDT (Roelf Baker made) active mini whip.
The Pixel is ~5 feet off the ground, mounted to a tripod, isolated properly (per instructions), sitting on a cement patio, about 5 feet from the house. 50 feet of 75 ohm coax connects the antenna to RSP2 SDR w/HDSR software.
The PA0RDT is ~20 feet off the ground, mounted to a PVC pipe, no grounding, sitting on a wooden deck, about 5 feet from the house. 50 feet of 75 ohm coax connects the antenna to RSP2 SDR w/HDSR software.
While tuning through the HF dial last night, all signals were significantly stronger with the PA0RDT. Changing the orientation of the loop made no difference.
Shannon Volmet was easily understood with the PA0RDT; with the Pixel, it barely produced a signal in the waterfall. Greece beacon "SVO" likewise was strong and very audible w/the PA0RDT; the Pixel was non-existent. STANAG signals were very pronounced and strong w/the PA0RDT while the Pixel was pulling in the signal, it was much weaker and very evident in the waterfall display.
Why would the PA0RDT mini whip outperform the Pixel mag loop? The PA0RDT should be grounded to improve signal and lower noise. Mine is not grounded; it is not performing as efficiently as it could yet it runs circles around the Pixel mag loop.
Does height above ground affect the Pixel?
Am I incorrect to assume that the Pixel mag loop should outperform the PA0RDT?
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I've never tried the PA0RDT antenna so I cannot comment on the comparison, but I have heard of the PRO-1B amps dying after long-term use. I presume the signals are 'decent' -- because without the amp I think you'd probably get fairly obvious weak signals?
I owned the PRO-1B and the Wellbrook 1530S+ and compared the two and they were pretty close but the Wellbrook clearly had higher gain amp.
My 1530 is at 5m and the PRO-1B was at 3m when I tested. (I sold the PRO-1B after a few weeks of testing.)
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I have a PRO-1B new in box. There are quite a few very good reviews of this antenna...
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The antenna works, it's sort of 'deaf' compared to an active mini whip. I expected the Pixel to blow me away, quiet, and a signal grabber.
This is in near-new condition, I doubt it has been outside. The aluminum element is clean and not oxidized in any way.
Is there a secret to map loops, height, or something?
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Is there a secret to map loops, height, or something?
Make sure there's power..? ;)
It shouldn't be "deaf" -- sounds like there's a problem somewhere. Power, coax, connections, etc.
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There's power to the pre-amp. Signals drop-off completely when powered-off.
It picks up plenty of signals, but compared to the PA0RDT active mini whip, it is far inferior. Trying to figure out why.
Would elevation make that much of a difference?
Canadian Weather @ 2749 KHZ with the PA0RDT is easily heard and understood, strong signal. On the Pixel, I can barely hear it or see it on the waterfall.
AGC is turn off, HDSDR settings remain the same between the two antennas.
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Would elevation make that much of a difference?
Not not from my experience. With respect to HF, height makes it more omni-directional and removes the nulls. Only large, metal objects will have any external influence.
The loop is directional when using frequencies < 8 megs or so. Sounds like Shannon Volmet is in the null of the loop (its sides.) (So if you put a stick in the center of the loop -- wherever it's pointing is in a null. The lower the freq the greater the null.
I only use AGC-S for SSB voice.
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Right now I am tuning Israel 4XZ @ 2680 CW. The PA0RDT is faint, but audible. I can clearly hear the morse code and it is visible on the waterfall.
The pixel doesn't pick it up, not audibly and not on the waterfall. Turning the loop makes no difference.