Oops--should be 24.9 MHz.

A coax trap of about five turns of RG-58 (6.3 mm dia) on a 30 mm diameter form about 2.86 meters from the feedpoint of a 4-meter tall pole should get you close. Prune the trap for 29.9 MHz, the maybe shorten the top section slightly for best signal on 17 meters.

I think it's in poor form to approach her at all, unless you are a very close friend of her and/or her husband. Then you might volunteer to help take down his antennas and help her appraise the equipment should she want to put it up for sale. When she feels it is appropriate to dispose of the equipment, she will do so.

W4VR answered your first question. Your second answer is "it depends." It depends on the type of lightning arrestor.

Gas discharge arrestors may let voltages get higher than 90 volts or so before conducting, so any charges below that threshold will stay on the line. A gas discharge arrestor shunted with a high value resistor or inductance to ground should bleed off practically all static charges.  

I personally do not see any advantage to hydrogen as a fuel for a generator, at least not with present technology. It requires a lot of energy to extract it from water, and under pressure it is extremely dangerous. I would think that a methane digester or ethanol still would produce a safer and more storable fuel for portable generators, and your stream-driven generator or solar panels could be used to charge storage batteries.

But, if you do go hydrogen, let us know how it works out.

Stew

Steve,

I would be very interested in the circumstances around the case you cite. I have a neighbor who is always passing on to me inspirational e-mails about some famous person or famous general or famous college professor, but the names, places and dates are generally omitted from the stories. Without evidence, even Snopes.com debunks most of these "famous" events.

From what I know about law, the "letter of the law" and the "intent of the law" can sometimes be two different things in court. When the FCC rules state "...any means of radiocommunication at its disposal...," the meaning is clear to me, but I'm sure some lawyers can somehow convolute it.

You also wrote, "This has already been adjucated on several occasions and the interpretation by the courts has been, 'An amateur operator, using amateur radio equipment, may transmit in the amateur radio allocated bands beyond the extent of his licensed privileges.'" Again, I'd like to see cases cited. As a long-time amateur, I've somehow missed hearing or reading about them. Perhaps an article in one of the ham radio publications is long overdue?

Stew - W5FYI

"Transmitting on frequencies for which you are not licensed is only allowed as a last resort, when no other means of communication is available - and it better be a life or death emergency; someone actually in danger of dying."

Actually, the rules state:
"§97.403 Safety of life and protection of property.

"No provision of these rules prevents the use by an amateur station of any means of radiocommunication at its disposal to provide essential communication needs in connection with the immediate safety of human life and immediate protection of property when normal communication systems are not available.

"§97.405 Station in distress.

"(a) No provision of these rules prevents the use by an amateur station in distress of any means at its disposal to attract attention, make known its condition and location, and obtain assistance.

"(b) No provision of these rules prevents the use by a station, in the exceptional circumstances described in paragraph (a), of any means of radiocommunications at its disposal to assist a station in distress."

I.e., it doesn't have to be a life-or-death emergency; it can be for protection of property as well.
---

"And in the process, you expose yourself to whatever legal action the particular agency wants to take for your unlawfully transmitting on their frequencies."

But it's not their frequencies; the FCC oversees their use, and the FCC rules just quoted says it's OK. If any explaining has to be done, it would be to the FCC, not the locals (although I bet many municipalities have local ordinances concerning use of police and fire frequencies, federal jurisdiction takes precedence). I'm not a lawyer; this is just my understanding of the rules.

I would expect that the radio is type accepted for amateur radio use, but not for public service, or any other service for that matter. Just because you can push a few buttons to change its operating characteristics should not necessarily alter its type acceptance. In other words, if you altered the radio by pushing the right buttons on power-up, then turned the radio off and sent it to an FCC lab, would they still view it as meeting type acceptance requirements? Undoubtedly, they would.

In fact, for emergencies, knowing how to transmit on police and fire frequencies could be handy since the FCC allows you to use any frequency necessary to summon help. Just don't convince your police and firefighting buddies they should get that model radio, too. As I said, it is doubtful that it would be type-accepted for non-ham use.

It's doubtful that one would help, but it certainly wouldn't hurt. Typically 8 to 10 turns of coax on a 8- to 10-inch diameter form will do. However, a better approach might be using an unun to match impedances. Assuming your transmitter and coax have characteristic impedances of 50 ohms, and your resonant mobile antenna has an impedance much lower than that, an unun transformer makes sense, and there are plenty of designs for making one.

FYI - Stew

"Could I put a 50 Ohm resistor across each one and see which one gave me 1:1 @ 147.000?"

Maybe, if you use a non-inductive resistor. But there is an old saying: "A man with a good watch always knows what time it is. A man with two watches can never be sure."

Consider, too, the wide frequency range you are measuring. Most test equipment simply fails at frequency extremes, even my commercial non-inductive dummy load has greater inductive reactance at VHF than it does at HF. You just have to learn the limitations, or spring more bucks for better test gear.

Just my 2¢ opinion - Stew

I use the formulas from the ARRL Antenna Book for "Optimum Design of Short Coil-Loaded HF Mobile Antennas"  but the formulas work well for VHF antennas as well.  A number of years ago I wrote the computer programming column in WorldRadio magazine, and one of my early articles presented a BASIC program based on these formulas for Tandy and Radio Shack PC-4 pocket computers (May 1991 issue). I later adapted the program to PC-type computers (February 1999).

The formulas are not too intimidating, but the Antenna Book takes about seven pages to explain them in the chapter on Mobile and Maritime Antennas, so I won't try to go into them here. However, they are easy simple enough to adapt to more modern programming languages, and to Excel.

FYI - Stew

Bob,

You could base load the spring steel, similar to the way some mobile HF antennas are base loaded. For 13.5 inches of radiator, you would need about 0.16 µH of inductance, which is about 4.3 turns wound to a length of ½" on a ½" diameter form.

You could also find longer spring steel "piano wire" at a hobby shop, especially one catering to model airplane hobbyists. In a pinch, brazing rod would work as well.

FYI - Stew

Congratulations! A counterpoise is a counterbalance for currents being fed into an antenna, generally an end-fed halfwave or similar longwire antenna. The theory is that for currents to flow into the antenna from one conductor of the transmission line, an equal current must flow out of a counterbalancing wire (counterpoise) into the other wire of the transmission line. Fortunately, end-fed halfwave antennas don't have very much current at the feed point, so the counterpoise doesn't have to be very large--maybe a tenth of a wavelength or so.

A quarter-wave vertical can work with a counterpoise, but in this case the counterpoise should be of equal length to the radiating element because currents are high at the feedpoint. A quarterwave vertical is more efficient and omnidirectional if installed above a ground plane or radial field. If the vertical is a half wavelength tall, and fed at the base, then a short counterpoise will certainly help, and a halfwave vertical does not require an extensive radial field.

Sometimes amateurs who live in apartments high above a real ground will lay counterpoise wires along the floor of their shack, generally making them a quarter wavelength long for each band of operation.

FYI - Stew

I took a look at W1HUE's article in The ARRL Antenna Compendium, Volume 2, and it looks like the standard formulas for inductance and capacitance hold; that is, capacitance is the coax's characteristic capacitance per foot, and inductance is calculated the same as if it were one solid conductor (i.e., not one conductor within the other, as in coax). What Larry did in his article to present a BASIC computer program that took inputs of coax diameter, coil form diameter, coax capacitance per foot, and trap frequency; and provided number of turns of coax for the trap, the length of coax needed to wind the trap, the amount of capacitive and inductive reactance, actual capacitance and inductance, and an "effective" length (the amount of length to shorten the next leg of the dipole by).

Obviously, Larry wrote the program back in "the day" when most hams had BASIC packaged with their computer's DOS, but it shouldn't be difficult to convert the BASIC listing to Excel. If you still have BASIC somewhere in your computer, you might try requesting EAST.BAS from either Larry or the ARRL.

By the way, I recall two different ways to make coax traps, but I'd have to look at my notebooks to find the differences. You might research the following issues of QST: May 81 and Dec. 84, and Ham Radio Oct. 1981. The construction method Larry used was to connect the braid of one end of the coil to the center conductor of the other.

FYI - Stew

Good quality PL-259 hardware speaks for itself. I swear, some of the plugs I've seen were chrome or nickel plated, and wouldn't solder worth a flip. I found that by drilling out the solder holes, making them a little larger, and scraping the plating away from the copper or brass underneath, made attachment much easier.

I have found that resistance soldering is a fast way to heat up the barrel quickly. Take the heating element out of a 140 watt or so solder gun, then hold the gun's two prongs against the PL-259 barrel and pull the trigger. The solder should melt within seconds.

FYI - Stew