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Electromagnetic tomfoolery or what?


Izen Ears

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  Okay, so I'm running the Comtek BST-25 with the phase right antenna, no problems.  Suddenly I see the antenna LED blinking, indicating the BST doesn't think it's connected to an antenna.  But it was. 

  Of course first thing I think of is the cable, so I go to play around with the connection.  Before my hand gets to the connector, the light stops blinking!  I move my hand away and it starts blinking again. 

  It was like a theremin's volume bar, when my hand got close to the phase right it saw the antenna, when I moved my hand away it stopped seeing the antenna.

  I looked around and saw I had put my sharkfins on C-stand right next to the right phase antenna, about 2 feet away.  (They had to be quickly moved to the cart for a turnaround shot.)

  I moved the sharkfin another foot away and the light stayed off, all was well again.

  Why on Earth would a C-stand and a sharkfin make the BST stop seeing its antenna?  Glad I figured it out enough to make it better, but I'd love to know what was going on.  Anyone else experience anything like this?

  Dan Izen

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Maybe the C-stand had just the right wavelength to make it a Phase Wrong?

I've seen weird things happen with Comteks and Lectros, like with thin wooden doors that you wouldn't think would cause any interference at all (with TX and RX 15 feet away from each other). Maddening.

There's a lot of "black art" associated with RF. At least you figured out a solution. I have a suspicion that a solid metal stand connected to a sharkfin can't do it any good. In a perfect world, I think a carbon fiber or wood stand would be a lot more neutral, but in real life, it wouldn't be as easy to use.

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  Black arts in RF, I believe it.  I wouldn't be surprised if a scandal revealed an arcane incantation as a last step to make all wireless devices work!  What's really weird to me was that my hand would 'fix' the blinking light, perhaps my electromagnetic field was disruptive to the C-stand's?

  Dan Izen

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I have noticed as well that, on occasion, pinching an antenna of a wireless can occasionally boost the reception. This is esp noticeable on the Sennheiser G2, as you can see the rf signal increase right on the display, and hear the signal clean up a bit. Not sure why, but I do it when needed, and it has helped me get the shot a couple of times.

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  Hmm, before this weirdo incident I had only seen that light blink when I was unplugged from the right phase (it was an accident and that light saved my butt!).  With the screw on guy it never blinks.

  Senor McIntosh - maybe you've got something similar to what I had going on?  Perhaps there's some metal rod nearby the antenna that's causing it to be wonky or something.

  Before I moved the C-stand and got the light to stop flashing, I did a test walking around and I did hear rf hiss 10' away, but after I moved the c-stand it was clean.  Too bad we can't put on goggles and see all the rf swirling about and easily identify what's causing problems.

  For that matter it would be cool to have goggles that saw sound waves bouncing around!

  Dan Izen

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  Hmm, before this weirdo incident I had only seen that light blink when I was unplugged from the right phase (it was an accident and that light saved my butt!).  With the screw on guy it never blinks.

  Senor McIntosh - maybe you've got something similar to what I had going on?  Perhaps there's some metal rod nearby the antenna that's causing it to be wonky or something.

  Before I moved the C-stand and got the light to stop flashing, I did a test walking around and I did hear rf hiss 10' away, but after I moved the c-stand it was clean.  Too bad we can't put on goggles and see all the rf swirling about and easily identify what's causing problems.

  For that matter it would be cool to have goggles that saw sound waves bouncing around!

  Dan Izen

I'm in South Dakota distracted with controlling the Pheasant population, but if I recall correctly, the antenna LED on the BST transmitter is for adjusting the telescoping antenna to proper SWR (Standing Wave Ratio).

The "black art" fix: Wile holding your hands high, walk slowly around the transmitter three times while chanting "Ohmmmmmm", then cut a piece of new black gaffer's tape to exactly .334 inches square and stick it over the LED.

Glen Trew

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