Towers & Such 2019

This topic contains 136 replies, has 19 voices, and was last updated by  LinleyG 1 week, 2 days ago.

Viewing 15 posts - 106 through 120 (of 137 total)
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  • #42835

    DarkStar
    Participant

    We’re going to delay simulcasting and coming up to full-power on KATU, hopefully just a day or two.

    #42848

    Jeffrey Kopp
    Participant

    I’m picking up the new KATU now. I entered 24 on one TV and it added 2.1 etc. by itself, and on the other TV I was able to do a “partial scan” of just channel 24.

    #42852

    LinleyG
    Participant

    KATU ch. 24 and KOIN ch. 25 indeed on the air but with strange, to me at least, results.

    I have been making daily measurements of the amplitudes of Portland’s DTV signals at my house in Aloha for a year now. I have two antennas. One is a small Winegard low gain antenna and the other is an old large all-channel, Channel Master high gain antenna on a rotator. My daily data is taken from the Winegard antenna because the large antenna has to be steered to get the maximum signal strength which makes it not entirely reproducible. The small antenna has a much larger beam width so it does not need steering so it is fixed, aimed at the tower farm.

    I make the amplitude measurements on an old HP spectrum analyzer that makes automatic channel power measurements. I have no idea if KATU and KOIN are at full power yet but what I observe is that they are within a dB or so of the same amplitude that KOIN on channel 25 was before the transition to the new site. (Of course there is no way to compare KATU who has just moved from channel 43 to channel 24.) Both antennas have a direct RG-6 run to the analyzer.

    For KATU on channel 24, the shape of the spectrum is nearly identical for both antennas with the signal from the Channel Master being about 10 dB louder, as expected. For KOIN on channel 25 I see a very different spectral shape between the two antennas. The signal from the Channel Master is relatively flat while the signal from the Winegard has a >10 dB v-shaped divot about 2 MHz above the lower channel edge. At times today KOIN’s spectrum was flat but tonight it is again divoted on that antenna. Rotating the Channel Master +/- 60 degrees does not show any off angle reflections that the high gain antenna is excluding. But, just to add interest, some times KOIN’s signal is flat, nearly ideal on the Winegard antenna.

    I cannot explain what I am seeing. I have looked at KOIN’s signal from its old site for a year and have never observed this divot or any variability in spectral shape at all. So, I don’t really suspect that the gremlin lives at my house. Yet, consistently the high gain Channel Master antenna shows a clean channel 25 signal and the low gain Winegard antenna does not, at least most of the time.

    Observing the flat channel 25 signal off of the Winegard antenna at times is also a real puzzle. My only thought is that perhaps KOIN is transmitting from its old site part of the time while work is being done on the new transmitter.

    I have a photo of the effect that, after half an hour of trying various ideas, I have been unable to attach to this posting. Someone put one of my photos on this site once before but I never learned how. I will send the photo to anyone who wants to see it. K7HFD at ARRL dot org

    Linley

    #42859

    Alfredo_T
    Participant

    I would like to see the spectrum analyzer screenshots, but the e-mail address in the post above does not work. I tried typing the callsign in lowercase, but either way, ARRL’s server says “user unknown.”

    #42864

    Andy Brown
    Participant

    Linley,

    You can not upload a file to this forum. You have to host the file on a server and then link to it.

    Last time, that’s what I did in order to display your image. When you correct your email address, I’ll email you and you can send me the file and I’ll upload it to my web site and post it here.

    #42867

    LinleyG
    Participant

    Too late (for me) at night, too much of a hurry and (gasp) relied on dim memory:

    Real e-mail drop is k7hfd at arrl dot net . I was trying to not post my prime e-mail address.

    Thanks for the help with the photo.

    Linley

    #42873

    DarkStar
    Participant

    KATU is simulcasting on UHF channel 24 currently at about 500 kW EIRP. I’m pretty sure KOIN is also at 50%/500 kW EIRP as well.

    Combiner issues are preventing us from going to full power at the current time, but they should get worked out soon. Expect KOIN to switch to the aux site while that is being done (KATU on channel 24 will just power off).

    Next Friday, we’ll be powering off the transmitter on UHF channel 43 sometime in the afternoon and then it will be moved to channel 24.

    #42874

    LinleyG
    Participant

    A three port combiner, one with two of the ports on adjacent channels would be a very interesting object. At the 60 kW input power/port level, it must be downright awesome.

    Linley

    #42875

    Jeffrey Kopp
    Participant

    Even at half power, reception is much improved over several months ago.

    #42879

    LinleyG
    Participant

    Gathering data, KATU’s new antenna is 2.1 degrees above the horizon at my house. Their antenna’s published vertical pattern indicates that the field that far below the horizon is about 0.45 that of the main lobe.

    Thus., when I measure their signal as roughly the same at my house that means it is much greater (6 dB or 7 dB?) than it used to be further away from the transmitter. A good design; it doesn’t over illuminate the foreground and saves the bulk of its power for greater coverage.

    Linley

    #42882

    Andy Brown
    Participant

    Here’s Linley’s spectrum analyzer image.

    #42914

    msndrspdx
    Participant

    T-Mobile Facebook ad says that KATU will change frequencies tomorrow (Friday 10/18/2019). Over the air viewers will need to rescan their TVs or DTV tuner boxes. The ad contains a link to the FCC webpage covering the subject. Interesting that this is a T-Mobile announcement, rather than one from KATU.

    #42915

    nosignalallnoise
    Participant

    They should have said “MAY need to rescan”. “WILL” is definite, “MAY” is speculative. The reason I say this is there are some receivers (Philips widescreens in particular, from personal experience) that automatically scan periodically, relieving the user from having to manually do it. There may be other makes/models that have this feature.

    Seems like nowadays it should be a standard feature in just about all receivers, by default. It certainly doesn’t cost more to manufacture than a strictly manual-scan device since it’s just lines of code in firmware.

    #42928

    semoochie
    Participant

    The TV I have gives me two of each 10.1-4. The second ones aren’t as strong and I always remove them after scanning. I would rather not make this a continuous habit, so I’m glad mine doesn’t do that. This is the second TV I’ve had that repeats channels and it’s a different brand, so this must be a common problem.

    #42931

    Jeffrey Kopp
    Participant

    OPB has a translator in the West Hills that identifies as 10.1-10.4 as well. This is the second 10.1-10.4 your TV is picking up on the scan.

Viewing 15 posts - 106 through 120 (of 137 total)

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