LPFM - Most off-the-wall question of the day

[Goat Rodeo Cowboy]

I remember seeing a TV bit on PBS about an LPFM that was able to get back on the air quickly after hurrican Katrina and was quite the communications hub for a very disrupted small town along the Gulf Coast.

If you operate in the hurricane area, or in tornado alley, or maybe in some sever winter weather zones, any kind of station has to consider how they will recover from a disaster. Having an auxiliary transmitter and antenna would be something to consider. (I know... considering the finances of so many LPFMs that seems financially out of the question.) Obviously for not a whole lot of cash you could stash an extra transmitter and antenna is some sturdy location and bring it out when needed. Contact FCC for and Emergency Waiver or STA to put it is service.

So his is the question: Would the FCC approve an Auxiliary transmitter set up and license it so that it would be ready to rock-and-roll in a matter of minutes in case power was lost to your main transmitter site... or a tornado blew that tower down?

 

[Bongwater]

I remember seeing a TV bit on PBS about an LPFM that was able to get back on the air quickly after hurrican Katrina and was quite the communications hub for a very disrupted small town along the Gulf Coast.

If you operate in the hurricane area, or in tornado alley, or maybe in some sever winter weather zones, any kind of station has to consider how they will recover from a disaster. Having an auxiliary transmitter and antenna would be something to consider. (I know... considering the finances of so many LPFMs that seems financially out of the question.) Obviously for not a whole lot of cash you could stash an extra transmitter and antenna is some sturdy location and bring it out when needed. Contact FCC for and Emergency Waiver or STA to put it is service.

So his is the question: Would the FCC approve an Auxiliary transmitter set up and license it so that it would be ready to rock-and-roll in a matter of minutes in case power was lost to your main transmitter site... or a tornado blew that tower down?

I would like to think they'd say yes, but LPFM is not much more of a priority to the FCC than a translator. That's how the LPFM Act was written BY DESIGN (thank you NAB.) All I can say is hope for the best, but assume the worst.....

I'm not much of an engineer. But I would imagine it depends on where it is really. Just going by basic physics, I'd say in the worst case scenario, since tornadoes and hurricanes cover a WIDE area all at once it would be tricky. You'd want to put it on something that can withstand 200 mph sustained winds (with the weather is these days, you just never know) and not many non-brick/concrete buildings can do that. A mast securely bolted and grounded to a height proportionate building would work (if you can get steady, long term permission from the owner. Good luck.) But if you're going to do that with an auxiliary transmitter and antenna, you might as well get the main one hooked up to one too. Some TIGHT STL linkage is a MUST.

Power is a huge problem, you'd want to have generators that aren't exposed (or potentially exposed) to these elements as well. And can be switched on when the main power goes without missing a beat. Again, this is just ideally. Mileage varies in the real world.

The details get Greek to me from there.

History teaches us the most resourceful broadcasters in these areas always plan for the worst in their initial designs. But alas, money is the 800 lb. gorilla in the room and the costs/red tape of these safeguards usually will kill an LPFM station before the ink dries on the first application. But the benefit of not having to replace expensive towers and transmitters at the worst possible time will make it all pay for itself instantly if the worst should happen.......

 

[Black_Shire]

A cheap and quick-to-implement alternative would be a Part 15 AM transmitter (or a small 20 watt night-time power/backup AM transmitter), an antenna impedance matching network, a small generator or a battery/charger/solar panel system, a full-size wire monopole antenna (1/4 wavelength, 1/2 wavelength, 3/8 wavelength, or 5/8 wavelength), copper ground rods, ~1/4 wavelength bare copper radial wires, UV-resistant black nylon cord, antenna insulators, commercial chloroprene or plastic advertising balloons, and several "Balloon Time" single-use party-size tanks of helium.

After the storm, a balloon would be inflated and moored to three ground anchors (tent stakes or corkscrew-type dog leash outdoor tie mounts would be ideal) that would be arranged in an equilateral triangle. The three lengths of UV-resistant black cord running from the ground anchors up to the balloon would form a tetrahedron, and the wire antenna would hang from the balloon down to the ground. The transmitter (or the antenna impedance matching network at the far end of the transmitter's coax) would be connected to the wire antenna here, and the ground rods and radial wires would be connected to the transmitter chassis (or the ground side of the matching network) here as well.

Also, a vertically-polarized co-linear emergency FM antenna could be made from several 1/4 wavelength pieces of coax, with the center conductor of each 1/4 wavelength piece soldered to the braid of the next piece and with all soldered joints weatherproofed with black UV-resistant shrink tubing. This would hang from the balloon (due to the greater weight, several balloons or a larger, finned "barrage balloon" would be required) and would be linked to the FM transmitter and the impedance matching network on the ground below with a long length of coax.


--Black Shire

 

[ngriffin]

The station in question is WQRZ-LP 103.5 licensed to one of the towns on the MS coast. They are licensed to an amateur radio group, so that probably helped a lot. I remember reading that they received an STA to run 1000 watts for a period of time.

 

[Black_Shire]

Another cheap, "quick & dirty" emergency LPFM antenna setup would be a balloon-supported omnidirectional periscope antenna. (A typical [directional] periscope antenna consists of a vertically-facing yagi antenna or a parabolic "dish" antenna located at the base of a tower. High above the yagi or dish, a metal mesh "flyswatter" reflector [tilted at an angle of 45°] is attached to the top of the tower.)

An emergency omnidirectional version of this antenna would use an LPFM transmitter, a yagi antenna, an aluminized mylar balloon (several feet in diameter), UV-resistant black nylon cord, three balloon ground anchors (large tent stakes, corkscrew-type dog leash outdoor tie mounts, pre-emplaced fence posts, sand-filled weighted containers, etc.), and helium (several "Balloon Time" single-use, party-size helium tanks might suffice).

After the storm, the balloon would be inflated and moored to the three ground anchors (these would be arranged in an equilateral triangle). The three lengths of nylon cord running from the ground anchors up to the balloon would form a tetrahedron, which would make the balloon more stable in winds than it would be if moored with only a single cord. The LPFM transmitter and the vertically-facing yagi antenna would be set up on the ground directly below the balloon at the apex of the tetrahedron.

As with the Echo series of aluminized mylar balloon passive communications satellites, the signal from the yagi antenna would be reflected all around the horizon after bouncing off the balloon, like a stream of water directed against a beach ball. A spherical balloon (like the Echo balloon satellites, only much smaller) would work, and a teardrop-shaped balloon (with a hemispherical "crown" and a conical lower "skirt") might be a better signal reflector.

 

[Goat Rodeo Cowboy]

Another cheap, "quick & dirty" emergency LPFM antenna setup would be a balloon-supported omnidirectional periscope antenna. (A typical [directional] periscope antenna consists of a vertically-facing yagi antenna or a parabolic "dish" antenna located at the base of a tower. High above the yagi or dish, a metal mesh "flyswatter" reflector [tilted at an angle of 45°] is attached to the top of the tower.)

I appreciate all the hints and suggestions.

Since my community has a 200 foot ridge running through it, I can probably own a 5 or 10 watt transmitter, a rather traditional antenna and some kind of 20 or 25 foot pole at the same cost or less than the balloon concept. It is a novel idea however.

Most of the answers were sensible, TECHNICALLY oriented responses.

Here is some of the "wild hair thinking" that went into the picture I painted in the original post. Our community may NEVER have a disaster type storm. By having an auxiliary installed, here is what it does for us EVERY YEAR. When we make a presentation before the Rotary Club and other community based groups, the presentation HAS SIZZLE when you say: we have disaster preparedness. It is an effort to enhance our ability for fund raising and donations.

On the technical side, I favor some kind of permanent installation of stand-by stuff. An LPFM is likely to have a very, very small staff. What if the only person on staff who knows where the hidden stuff is, the only guy on staff who know how to set up the balloon device for instance, is on vacation or in the hospital when disaster hits. How do you get it operational in that case.

Because of the ridge, I suggested that I might have one transmitter rather traditional..... 100 watts up on a stick, on the lower ground. The other one would be the low power unit... somewhere from 8 to 24 watts, depending on the exact location, on a very, very stubby mount. Now when the tropospheric conditions start playing games with reception, tunnelling brings signal in on top of me, then we can switch back and forth to see which signal produces the best results.

If you don't have a second licensed transmitter, you cannot do any of this trial and error stuff and be legal. Now, I might be so daring as to even temporarily relocate the low power transmitter for a horn now and then to test other locations. That would NOT be legal, but would not call attention to itself in such a way as to create calls to the FCC to report misbehavior.

I agree with those who say: The smart money is on buying a second transmitter and some kind of antenna and put it in the best storm shelter you can find. Drag it our someday if you need it. But that doesn't have the same "sizzle" when it is part of the fund raising presentations.