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Amateur (Ham) Radio BS and Callsign Thread!

Discussion in 'Sports, Hobbies & Interests' started by The Traveler, Jan 29, 2013.

  1. Mar 10, 2020 at 2:59 PM
    #6961
    m603holden

    m603holden @Koditten Pirate Radio member #063

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    The difference being is mine is for bonding, like you said though. I'm relying on the strap going right into the screw threads, not the bracket surface itself.
     
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  2. Mar 10, 2020 at 3:06 PM
    #6962
    m603holden

    m603holden @Koditten Pirate Radio member #063

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    ^

    One post up. I use it for general panel bonding. But that screw is uncoated where it touches the scrap and goes straight into female threads. More than enough surface area.
     
  3. Mar 10, 2020 at 3:07 PM
    #6963
    C41n

    C41n Gandalf Da Grey

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    This is a big concern of mine. Also one of the big reasons I am not ready to do any drilling.

    Thank you both!
     
  4. Mar 10, 2020 at 3:11 PM
    #6964
    m603holden

    m603holden @Koditten Pirate Radio member #063

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    Serrated washer. The paint has a cathodic mix in it. It'll essentially heal itself around the edges that dig in.

    61fWM9o5BYL._AC_SX522_.jpg
     
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  5. Mar 10, 2020 at 3:55 PM
    #6965
    DaveInDenver

    DaveInDenver Not Actually in Denver

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    Unexceptional
    I know that's the method we always parrot but how did you test to know it actually did anything?
     
  6. Mar 10, 2020 at 4:06 PM
    #6966
    m603holden

    m603holden @Koditten Pirate Radio member #063

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    For what? It has both continuity and surface area. My noise floor dropped about one S unit after it was bonded.
     
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  7. Mar 10, 2020 at 4:20 PM
    #6967
    DaveInDenver

    DaveInDenver Not Actually in Denver

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    Unexceptional
    You measured with a DMM, right? That tells you resistance, not impedance. Having good DC conductivity does not guarantee there's no reactance and thus high impedance. It's especially true as you go up in frequency and at UHF I highly doubt such bonding is at all effective.

    Anyway, never mind, the thought is going nowhere. We always tell new hams "do this" but never the why or theory. Point I was trying to get at was you can check (or infer anyway) impedance with an antenna analyzer, vector network analyzer or just an SWR meter.
     
  8. Mar 10, 2020 at 4:30 PM
    #6968
    m603holden

    m603holden @Koditten Pirate Radio member #063

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    My point was that if you didn't want to rely on the bracket nmo mount to make the bond, you can ground directly from the mount to the body if need be.


    I have no antenna there. There is no coax to test the impedance. The drop of 1 s unit in noise just from bonding the hood shows a successful bond and is on par with what is to be expected for such bonding.

    I could easily check the impedance by hooking a meter up to the farthest point in the strap and putting a probe to the farthest section of the hood, but why?
     
    Last edited: Mar 10, 2020
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  9. Mar 10, 2020 at 4:56 PM
    #6969
    maineah

    maineah Well-Known Member

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    Your bed rails are grounded they are not screwed into the plastic. Drill and tap a couple of (1/4 20) holes into a piece of 1/4 aluminum that will fit inside of the rail, slide it to where you want it drill matching holes in a aluminum angle drill a 3/4" hole for an NMO, bolt it to the AL plate slide it where you want it tighten the bolts (SS prefered). Try to get over the ground plane myth it will make you lose sleep.
     
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  10. Mar 10, 2020 at 5:20 PM
    #6970
    foy1der

    foy1der Well-Known Member

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    This ugly bastard is going to become my off center fed dipole. 4:1 current balun, ran it through my analyzer and got what I expected. Tomorrow I got to Home Depot to find a box. Then I'll measure up the wire. This is going to be the antenna that I bring camping with me, very excited about getting extra bands. I'm currently sitting at about $15 for the torroid, had the wire, couple of bucks for the box, and then some fasteners. Not too bad considering they go for upwards of $100 at HRO.
     
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  11. Mar 10, 2020 at 5:31 PM
    #6971
    DaveInDenver

    DaveInDenver Not Actually in Denver

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    It shows you've made an effective shield, likely from engine radiated noise primarily from the ignition system. That doesn't necessarily indicate effectiveness as a conducted ground plane for an antenna, especially at VHF and higher.
     
  12. Mar 10, 2020 at 5:34 PM
    #6972
    Sand Dog

    Sand Dog Well-Known Member

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  13. Mar 10, 2020 at 5:39 PM
    #6973
    joshuajayg

    joshuajayg Well-Known Member

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    I have a set of ditch light mounts off Amazon if someone wants them. Pay shipping and they are yours. Ended up just drilling a hole in my roof instead of playing with a non-intrusive mount. Never installed.

    LED Light Pod Metal Hood Mount Bracket Kit/Ditch Hood Light Brackets for 2016-2017 Toyota Tacoma - black. https://www.amazon.com/dp/B07PRG7MY3/ref=cm_sw_r_cp_apa_i_wodAEbDREWB0C

    I'd accept a donation if you want them but not needed.
     
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  14. Mar 10, 2020 at 5:47 PM
    #6974
    m603holden

    m603holden @Koditten Pirate Radio member #063

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    It's effectively the same test as running radials from your mobile to improve you stationary set up that the Arrl has published many times.
     
  15. Mar 10, 2020 at 5:51 PM
    #6975
    m603holden

    m603holden @Koditten Pirate Radio member #063

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    "A useful test of the quality of your ground is to lay out several long wires while you are stopped in your driveway. Connect them to the RF ground connection on your Smartuner. When you remove these temporary wires, reconnect your grounding system. The signal should get better. If it gets worse, your RF grounding system needs work."
     
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  16. Mar 10, 2020 at 5:53 PM
    #6976
    DaveInDenver

    DaveInDenver Not Actually in Denver

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    Unexceptional
    Look, we're going in circles. Using measured resistance and radiated noise floor reduction based on a low frequency, long rise time pulse like an ignition with perhaps harmonics to maybe 1 MHz is fine as an analog for an impedance measurement at HF but isn't a complete test. If you put a VHF noise source under the hood and see a one S-unit (6 dB) reduction in radiated noise immunity to your roof antennas then I'd happily admit to being unnecessarily pedantic.
     
  17. Mar 10, 2020 at 5:56 PM
    #6977
    DaveInDenver

    DaveInDenver Not Actually in Denver

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    I agree that trusting reciprocity is fine in this case. If radials improve reception then at the same range of frequency you have improved your transmitting performance.

    What I'm saying in all of this that bonding my sheet metal took a lot of effort and measurement to actually finally show any improvement on my old truck. Especially at UHF random lengths and indifferent terminations of braid doesn't work to actually create RF conductivity. That's why I didn't go to great lengths on trying to get those ditch brackets working well and just used ground plane indifferent antennas.

    Bonding is important if just for local noise reduction but it's not a one size fits all solution. You might need multiple lengths of braid. A bonding jumper might work well for one range of frequencies and be completely useless at others.
     
    Last edited: Mar 10, 2020
  18. Mar 10, 2020 at 5:57 PM
    #6978
    joshuajayg

    joshuajayg Well-Known Member

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    "Pedantic" is my new favorite word. I have been using it for a few weeks (usually in reference to myself.) :pout:
     
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  19. Mar 10, 2020 at 6:12 PM
    #6979
    m603holden

    m603holden @Koditten Pirate Radio member #063

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    Literally the whole point of the convo was just to say there's rf bonding between the bracket and hood because he was concerned about the bracket. Just gave reason why it was. Wasn't diving into propagation theory.
     
  20. Mar 10, 2020 at 6:31 PM
    #6980
    DaveInDenver

    DaveInDenver Not Actually in Denver

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    OK, fine.

    Wave propagation in a real material is precisely what's being discussed. So sure, there's conductivity (or maybe it's absorption, which is effective at reducing EM noise in this case just changing ignition EM noise into heating the braid slightly, as well as reflection) at some unknown frequency. What's happening at the frequency of interest is being ignored, but it's critical to having an antenna mounted on a ditch bracket present a useful radiation resistance and pattern. But whatever.
     
    Last edited: Mar 10, 2020

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