Here's the deal...I have an RF infiltration issue that's causing erratic operation of an LED beacon. In particular, it flashes 1 flash at full brightness & the next at about half brightness. It has no controller with it..uses the same incandescent controller as in the past. Reducing the FM power from 5KW ERP to 3.5KW ERP stops the problem so I'm not many DB away from success (rain also stops the problem for several hours suggesting that just the added capacity of wet tower light wiring to the tower is also enough to stop it). Most recent test was hanging a 100 watt lamp across the flasher output at ground level to verify that the flasher is working properly with the small load--it is. The 100 watt lamp flashes at full brightness while the beacon is erratic. The tower light wiring is outdoor rated romax which runs through the FM antenna aperture about 15' below the beacon. Obviously I don't want to place all the tower light wiring into conduit but maybe running the existing wiring that's near the antenna through conduit & grounding the conduit to the tower is a possibility. Which leads to this question : Is there flexible metal conduit rated for outdoor use? Thinking cap output appreciated...
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RF ON SOLID STATE LED BEACON
- Thread starter BobOnTheJob
- Start date
You might put a bypass capacitor across the a.c. line right at the beacon. Make sure that the capacitor is rated for high voltage. .01uf would probaby be a good value.
You can use the liquidtight metallic conduit outdoors. It's designed for wet locations, the metal is plastic covered. Would be under $75 for 50' of 1/2" plus connectors for each end. Available at Lowes or Home Depot.
I would connect it at the beacon, drop it past the FM antenna, and terminate in a box where it ends. Since the beacon shouldn't pull much current, you could run #12 from the beacon down to the box, and splice into the Romex at that point.
I would connect it at the beacon, drop it past the FM antenna, and terminate in a box where it ends. Since the beacon shouldn't pull much current, you could run #12 from the beacon down to the box, and splice into the Romex at that point.
Four tower array: never was able to get a solid state flasher to work on two of the three towers without conduit. The 50 kw day tower had conduit as it was newer. SS flasher worked good on it.
You've got long runs of wire between where it partially "grounds" to the tower at the obs fixtures.
May never get the RF off of it.
As for me, I would be hesitant to put anything (like a capacitor) that may need replacing after a lightning strike all the way at the top of a tower.
You've got long runs of wire between where it partially "grounds" to the tower at the obs fixtures.
May never get the RF off of it.
As for me, I would be hesitant to put anything (like a capacitor) that may need replacing after a lightning strike all the way at the top of a tower.
Appreciate the input everyone but especially TomT...I want a solution that my 60 year old bones can take up the tower with me and implement and 50' of 1/2" liquidtight with the #12's pre-installed at ground level just might be my answer. That will put it well above and below the antenna. I was thinking about grounding it at the top, bottom and middle but may opt to skip the middle in the interest of keep the water tight seal intact. Any other ideas are welcome but this is where I'm leaning for now.
That would be the plan...and with the top end terminated within the beacon, that should ensure that water is never an issue. Any idea what 50' of this stuff weighs?TomT said:
Have seen screen insterts that go in the knockouts. Lets the water out and critters from getting in.
We have tiny leaf cutter bees around here that fill up any holes that are the right size.
We have tiny leaf cutter bees around here that fill up any holes that are the right size.
I tried a toroid but all I had was a snap on that went around the Romax cable...unfortunately that didn't help. I also snugged the Romax against the tower legs/diagonals and tie wrapped the daylights out of it but the only place it wasn't was well above the antenna. That made no substantial difference. I wish there was a "snap on conduit" I could place around the existing Romax....that would be the simplest answer but if that exists, I am not aware of it. Tom Wells---thanks for the weight estimate...I think I can manage thatKmagrill said:
Update : The tower light AC wiring from 20' below the FM antenna to the beacon is now a pair of #12's in weatherproof flexible metalic conduit grounded to the tower at the bottom and to the beacon at the top (along with a small Ditek surge protector at the beacon). Several days of operation and the problem is gone. Worth noting that in the past, rain would stop the problem for several hours and it has rained almost daily since these changes, so I'm not ready to declare the problem corrected but these results are most encouraging. For the record, hauling up 50' of conduit with wire, the beacon and tools as well as the weight of the safety belt does slow a guy down.
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