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  • #19277

    The night readings added to my table, relative to 1080 day:

    freq day night
    910 -14dB -5dB
    970 +3dB +4dB
    1080 ref. -8dB

    Again, using a tiny meter and antenna with unknown frequency response.


    I did some additional readings, this time using a longwire antenna:

    Freq.    Day    Night
    910     -4.8dB     0dB
    970     +9.3dB  +9.3dB
    1080       0dB  -3.5dB

    On the longwire, I noted that on 1080, the signal strength jumps up and down both day and night. I tried to capture a reading that was close to the maximum. The other stations were stable to within +/-0.2dB. I think that most likely, there is some kind of knife edge diffraction effect being caused by the West Hills. If somebody in Portland could take similar signal measurements, the mystery would be solved.


    Here is another signal strength mystery, comparing KUGN (590 kHz) against KXOR (660 kHz), as received from Hillsboro. KXOR has 3 dB more transmitter power, but it should be at a slight disadvantage due to being at a higher dial position. When I measure the signal strengths, using the loop, KXOR is 8.9 dB stronger than KUGN.


    KXOR is double the power and a few miles closer plus newer tower/ground system.

    Andy Brown

    KUGN is DAN (directional antenna at night) and Hillsoboro is receiving less then the full 5 kW.

    KXOR is only 75 W at night.

    On a field strength meter, 9 dB difference is a voltage reading. Assuming day time measurements, 3 dB more power is 6 dB more voltage, not all that far off from 9 dB especially when you consider your location versus the locations of the two stations and all the topography in-between, the electrical length and physical length of the towers involved, etc. etc.

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