Legal 5-10W IF/RF Transmitter for Experimentation

Depending on what you're trying to do and whether the 160M ham band is still available, that might be an option. Not unlicensed, but you can easily get a license...depending on what you're gonna do with it.

And you don't even need a license, just a helper with a license. Call up a local ham radio club.

There probably are not many countries where transmission with 5-10W output power is possible without any licensing or registration at all, maybe with the exception of 27 MHz CB radio.

Most unlicensed modes are allowing much less power than that. On the other hand, most people grossly overestimate the amount of power required to make a given radio link...

Ham radio license is one correct method. 160m (1.8MHz) is very much still available as are 135kHz and 472kHz in many countries.

At 135 and 472 the power limit is defined by EIRP at 1 or 5W but to radiate that much with realistic antennas can take up to 1kW at the transmitter output terminals!

piglet

I'm not current on the Amateur Band rules, but could one still use this band (technically) if they were developing a commercial product?

I thought the Amateur band were strictly for non-commercial use. (?)

I probably don't understand, but if you are experimenting with data modulation, can't you do this with low power even through cables, without any RF getting into the ether? Mikek

Don't happen to live in Ohio?

There is some gray area there. It certainly wouldn't be kosher to sell a commercial product (other than one designed for Ham use) using the Ham bands. "Experimenting" is little different.

Those are still the rules.

However, if you perform some new modulation tests with an other radio amateur using amateur radio rules and after detecting that your systems works OK, just create a commercial product :-) :-)

What I do not understand what "AM" or "IF" is referring to ?

"AM" is amplitude modulation and some US people incorrectly calls the

What "IF" band is referring to is a mystery, "IF" is a short for Intermediate Frequency. In some radios this refers to 262 or 455 kHz, but could as well refer to 9 MHz (old amateur radio) or 45 MHz more modern general coverage radios.

If the OP intended something below 2 MHz, the 5-10 W power requirement is a mystery. The ground wave propagation is proportional to transmitted power, so doing the test at some shorter distance would get usable results.

However, if the intent is to use NVIS reflection through the ionosphere, those power levels are justifiable for 1-10 kbit/s data transfer rates.

Here's a low power unit for $45.

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Sorry about the length.

It's a very gray area. There have been quite a few commercial ventures that did their initial testing and experimenting on ham radio frequencies. There's also an unanswered question of where are commercial ham radio equipment vendors suppose to do their development if not on ham frequencies? It's generally considered a bad idea to ask the FCC for clarification as they tend to produce some rather odd answers, such as when they were asked to clarify whether commercial traffic over packet radio was acceptable, and delivered instead a requirement for authentication (which most everyone ignored).

There are some technical limitations as to what can be done with ham radio. The FCC likes to be able to monitor transmissions and therefore limits modulation and encoding schemes to well known or published formats. For example, spread spectrum is (or was) limited to only 3 spreading codes.

If you're doing something that is currently outside of the existing rules and regulations, you can apply for an STA (Special Temporary Authority or Developmental License). The users of the new VLF frequencies operated under an STA for years, until it was recently approved for ham use by the FCC.

The easy way to use ham frequencies for development is to simply not mention that the prospective device will ever be sold commercially. The other way is to use the ISM bands, which seem to have become the dumping ground for any new technology, which now includes their use for cell phone connectivity.

The original question is too vague to be answered with specifics. The misuse of some radio related terms suggests that the proposed product definition is rather badly muddled. I can't be more helpful without clarification.

Yeah, something like that:

(k) No station may transmit in the 135.7-137.8 kHz (2200 m) band with a transmitter power exceeding 1.5 kW PEP or a radiated power exceeding 1 W EIRP. (l) No station may transmit in the 472-479 kHz (630 m) band with a transmitter power exceeding 500W PEP or a radiated power exceeding 5W EIRP, except that in Alaska, stations located within 800 kilometers of the Russian Federation may not transmit with a radiated power exceeding 1 W EIRP.

Additional limitation on the size of the antenna insures that antenna efficiencies are dismal. The limit is 60 meters (197ft) AGL (above ground lavel) for transmitting antennas on 630 meters and 2,200 meters. Typical efficiency for such an antenna is about 0.2% where

Also, one is suppose to get permission from the local power company to make sure the transmitters don't trash their PLC (power line communications) system.

Ultra-sound or laser beam. The sound trough air or water or soil. As long as you keep the power down to safe levels.

I think in the USA it isn't really allowed to do new modulation methods on amateur radio without all kinds of difficult paperwork and negotiation. At least that is what I hear from US amateurs that feel limited by the FCC rules.

But usually not with 5/10 Watt power...

That 0.2 % on 137 kHz sounds a bit optimistic, unless you have a huge top-capacitance, a good loading coil and a good ground (sea water).

Thanks. I have just ordered one. I am hoping it will be adequate for initial experiments. Part of the project is evaluating antennae performance.

Robert Miller

Yes, it's optimistic. See: "Antennas for 136kHz" "On LF the situation is completely different, efficiencies of most antennas used by hams are in the range of 0.01 to 1%."

For a simple base loaded vertical antenna, the radiation resistance is quite low, typically about 0.05 ohms. A suitable loading coil will be fairly low Q and produce a resistive loss of about 30 ohms. Ground resistance will be somewhere between 30 to 150 ohms. I'll use 50 ohms. The radiation efficiency is therefore: rad_eff = 0.05 / (0.05 + 30 + 150) = 0.028% If I add ground radials, in highly conductive soil, a capacitive hat, and a silver plated loading coil, I can probably increase the radiation efficiency to 0.2%. However, I haven't tried it (yet) so I don't know if it can be done.

Title 47: Telecommunication PART 15?RADIO FREQUENCY DEVICES Subpart C?Intentional Radiators

(a) The total input power to the final radio frequency stage (exclusive of filament or heater power) shall not exceed 100 milliwatts.

(b) The total length of the transmission line, antenna and ground lead (if used) shall not exceed 3 meters.

(c) All emissions below 510 kHz or above 1705 kHz shall be attenuated at least 20 dB below the level of the unmodulated carrier. Determination of compliance with the 20 dB attenuation specification may be based on measurements at the intentional radiator's antenna output terminal unless the intentional radiator uses a permanently attached antenna, in which case compliance shall be deomonstrated by measuring the radiated emissions.

Good luck.