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Ham radio RFI controlling my HR24s

Discussion in 'DIRECTV HD DVR/Receiver Discussion' started by AirShark, Oct 7, 2012.

  1. Oct 7, 2012 #1 of 46
    AirShark

    AirShark Legend

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    We recently moved to a new home and Directv was kind enough to replace my trusty old HR20-700 dvrs with two HR24 units.

    I'm an amateur radio operator, N6LY. I transmit 100w on 10,15,20,40,80m through an Alpha Delta DX-CC fan dipole. It's on a 33ft mast, partially over one corner of the house (2 story). Everything is grounded and tied to the main ground. I have two current baluns on the feedline.

    I recently got back on the air. Yesterday, during about 7 hours of California QSO Party operation, I noticed the hr24 upstairs was recording random programs. Upon further inspection, I see that each box turns itself on/off when I key on 80/15m.

    I unplugged all cabling into the HR24s except for the power. They still turn on/off (just like pressing the capacitive touch button) on the front panel.

    There is no indication of any sat signal interference during operation. Only this odd controlling behavior.

    I'm going to make a trip to radio shack today for a bag of snap on ferrite chokes on the power cord. If that doesn't help I don't know what else to do other than wrap the darn things in tin foil or something.

    If it was the sat cabling I'd be a little relieved as I could work on the grounding system. The fact that its either getting in via the power cabling or directly into the units themselves is troubling.

    Any other ideas?
     
  2. Oct 7, 2012 #2 of 46
    bobnielsen

    bobnielsen Éminence grise DBSTalk Club

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    Bainbridge...
    I've had good results with those Radio Shack ferrite cores on things like computer keyboards but haven't run into any issues with my Directv receivers (H24 and HR24). Do you have any other RFI sensitivity issues?

    Bob, N7XY
     
  3. Oct 7, 2012 #3 of 46
    Davenlr

    Davenlr Geek til I die

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    Is that unit set to use the RF remote?
     
    1 person likes this.
  4. Oct 7, 2012 #4 of 46
    AirShark

    AirShark Legend

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    No, they're not set to use RF remotes. I have Harmony ONE controllers that only run IR, so I have them set for IR.

    I haven't had any other RF issues except for a set of computer speakers. Ferrite beads took care of that minor noise easily.

    Here's the funny thing.

    The HR24 downstairs, furthest from the antenna: I placed one sheet of foil on top, not the sides, of the HR24, crumpled to touch metal on the back of the chassis. No more turning off on any of my serviceable bands!

    The HR24 upstairs, closest to the antenna: I placed the same foil and it didn't work. It turned on less often, but still turned on/off. I placed TWO sheets of foil around it with a 4 inch hole in the front for the IR sensor. Now I haven't been able to get to cycle when on the air.

    I'm going to do a final run in the CA QSO party today, we'll see what happens.

    I'm going to pick up some ferrite beads anyways, just because I was out. I guess I could make something up with black cardboard or construction paper that I could place/stick onto the HR24 boxes that wouldn't look totally ghetto. Also I'd need to cut out ventilation slits to match the side of the chassis.

    I'm guessing based on evidence that it's probably getting into the RF receiver built in to the HR24s?

    Could it be this simple? Totally weird right?

    -Bryan, N6LY
     
  5. Oct 7, 2012 #5 of 46
    Davenlr

    Davenlr Geek til I die

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    Yea, seems strange, since I thought when the unit was set to IR, the RF receivers were disabled. Maybe not so much :)
     
  6. Oct 7, 2012 #6 of 46
    n3ntj

    n3ntj Hall Of Fame

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    Rather odd... I am also a ham (N3NTJ) and an electrical/RF engineer but have never had any issues with any of my HR-2x machines turning on/off or anything else while operating HF, VHF, or UHF. Not sure what freq(s) the RF remote runs on, but you mention your IRDs are set to IR remote mode.

    How close are your transmission lines or antennas to the location where your IRDs are located? Do the satellite and ham transmission lines every come near each other?

    I also occasionally find my HR24 has randomly recorded programs that nobody in my house recorded (often in the middle of the night when I am not on the air)..and figure that is a software bug. I have no other hams/transmission sites near my QTH.

    Sounds like you will need to do some diagnostics such as proximity of components. I'd try some RF chokes on the satellite lines as if you're only operating HF, I recall the Ka/Ku signals are in the 300 MHz range when fed to the IRD/BBCs.
     
  7. Oct 7, 2012 #7 of 46
    AirShark

    AirShark Legend

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    I'll draw a map of the orientation of my antenna and IRDs in a few minutes.

    The Sat wiring and feed line do not come near each other at all except for maybe 8ft in the attic. The sat coax is in a shielded bundle with other pre-wired house wiring. I have a 1:1 current balun at the feed point and a coil choke balun before it gets to my shack.

    The problem is that on BOTH IRDs with all cabling disconnected except for power, this unwanted control happens. I'm not sure adding chokes to sat transmission line, phone, cat6 lines would do any good.

    I just did a final run at the California QSO party for 5 hours straight with the tin-foil wrap and there was no unwanted behavior from the IRDs. I'll prob just go pick up some snap on beads from Radio Shack for the hell of it, but I think I'm going to have to construct some sort of foil-lined shield for the IRDs here pretty soon.

    I'm not sure about adding RF chokes to any other equipment except the power cabling, which I'm still not convinced of. My gut tells me it's getting into the radio receiver. Thus no RX issues, only things happening that could be done with a remote control.
     
  8. Oct 7, 2012 #8 of 46
    carl6

    carl6 Moderator DBSTalk Club

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    I don't think that is likely, as the RF remote works on 430 MHz. I run 50 watts regularly on VHF and UHF, but don't have an HF transmitter right now. I've never had any problems with radio rf interference with DirecTV equipment, and some of my transmitters are within 18" of the DirecTV stuff.

    Carl, N7KUW
     
  9. Oct 7, 2012 #9 of 46
    AirShark

    AirShark Legend

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    Doesn't seem likely to me either, but I can't discount what I see.

    1. Turn off IRD (either one, doesn't matter)
    2. Disconnect all cabling from IRD, except power.
    3. Key down on mostly 80m/15m SSB. Other bands work sometimes, but not reliably)
    4. IRD Turns on/off randomly
    5. Turn off IRD
    6. Wrap IRD in aluminum foil, touching metal on rear of IRD
    7. Key down on 80/15m again.
    8. Nothing happens on IRDs

    I also run VHF/UHF, but that's been running for months with no issue. This only started with the addition of a new HF antenna at my new QTH.
     
  10. bobnielsen

    bobnielsen Éminence grise DBSTalk Club

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    Bainbridge...
    The older DVRs had a metal case which provided much more isolation than the plastic case used on the HR24 and some of the other newer models.

    The Radio Shack snap-together core (#23-104) might help if you can get it as close as possible to where the power cable plugs into the DVR. I don't know how many turns of the power cable would fit, however (multiple cores may improve the isolation). Since you have had some success using foil, you probably don't need much filtering.

    A power line RFI filter (such as http://www.curtisind.com/files/rfiFilters/F1900-RFI-Filters.pdf) would probably do a good job but might be hard to find and/or pricey and would require splicing into the power cable.

    If it were an owned, rather than a leased box, there are better approaches but....
     
  11. AirShark

    AirShark Legend

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    I'm going to go buy a bag of large ferrite cores from Ham Radio Outlet tomorrow. Hopefully I'll have some luck stacking them up.

    The power cords are removable. I don't see a problem in buying an extra and splicing a line rfi filter in.

    If the foil works and I can back a few layers on black construction paper, that might not be bad either.

    I love a good adventure mystery :)
     
  12. azarby

    azarby Hall Of Fame

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    Since putting foil around the box helps mitigate the problem, you are getting spill over from either your cable or transmitter. This does not seem to be coming through the cabling. I would look at your transmitter or antenna lines and see where you have an RF leak. Time to get the old sniffer out.
     
  13. NR4P

    NR4P Dad

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    Can you temporarily run the hr24 on a ups only no commercial power to see if you decouple from AC power if problem disappears?
     
  14. n3ntj

    n3ntj Hall Of Fame

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    Like the others mention, it sounds like RF is getting into your units from RF leakage somewhere. Not sure if you mentioned how much RF power you are running.

    A foil cage should help prevent this issue however can definitely get in the way of normal usage. Problem is that you don't want to tightly foil the sides and tops of the IRDs as they need adequate ventilation. Not sure if an RF choke on the power lines would make a difference since foil on the units themselves partially solved the issue.
     
  15. Stuart Sweet

    Stuart Sweet The Shadow Knows!

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    I've heard of this issue before, and it's definitely RF leakage into the box. Since you are not using an RF remote you should be able to put the receiver in a Faraday cage. Since it seems like you're pretty savvy about broadcasting you can probably find out what the right size mesh would be right for isolating the signals you're generating and that should let the HR24 vent properly and give you the isolation you need.
     
  16. paulman182

    paulman182 Hall Of Fame

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    Move your ham antenna if possible.

    I can run 1300 watts into ladderline six inches from one of my HR-24s with no ill effect.

    My 400-foot doublet is 300 feet from the house and my trap vertical is 50 feet away.
     
  17. AirShark

    AirShark Legend

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    With the antenna disconnected, 50ohm dummy load attached, it sweeps fine on an antenna analyzer. 1:1 across any frequency. I also have a Narda rf field strength safety meter that registers zero when actually sitting on top of my transmitter during key down. Nothing. I'm fairly confident that anything coming out is coming directly from the radiating elements.
     
  18. AirShark

    AirShark Legend

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    I can do that. I'll give it a shot today.
     
  19. AirShark

    AirShark Legend

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    I'm only running 100w - prob 1.5dbm of cable loss...so less than 100w radiated.

    There are no vent holes on the top of my HR24s, only the sides and back. Shouldn't be hard making something nice that matches the vent hole cutouts. To be clear, I haven't wrapped the entire IRD in foil, just a piece on top, wrapped to barely touch metal chassis on the back, barely hanging over the left side of the chassis.

    So far, foil has completely solved the issue it seems. Did a 6 hour final run on the CA QSO Party yesterday, not one problem with either IRD.
     
  20. AirShark

    AirShark Legend

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    Thanks, ill look into it.
     

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