First, differentiate between loaded and tuned.

Loaded would mean that there is some kind of AC resistance load on the antenna terminal like an antenna or a dummy load.

For a low power transmitter a dummy load can be a 47 Ohm 1/4 watt resistor or even an incandescent flashlight bulb.

Once there is a load on the antenna terminal of approximately 50 Ohms you can operate a transmitter and begin the tuning process.

So, if the antenna terminal is loaded you can operate the transmitter when it is not properly tuned because that's the only way you can tune the transmitter to its antenna or dummy load for testing.

It is probably best to avoid operating a transmitter over a long period of time in an un-tuned, or mis-matched, state but the time required to dial in when tuning shouldn't be a problem.

Once you get the hang of how your transmitter tunes up, you can install the transmitter and permanent antenna and tune the assembly for best performance.

You'll want to check the tuning from time to time, as well, because weather and wind can affect the antenna and tuning.

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You peaked my interest with your remarks on the operation of an improperly tuned transmitter "over a long period of time". Can you tell me why this would be a problem?

Your post on this issue also indicated the need for occasional retuning because "weather and wind can affect the antenna and tuning". I think I understand the relationship between rain and soil conductivity and how ground moisture will affect the performance of a buried ground radial system, but I don't understand what impact the wind would have on an antenna. Could you expand on this for me?

Thanks again for helping me with all of this!

Sure. Again, always deferring to the designer for the specifics on that, but in general if a transmitter isn't tuned to the antenna load that transmitter will be electromechanically stressed. It's very subtle with a 100 mW unit, catastrophic with a high-powered transmitter, but the stress is there.

What that means is that if a properly loaded and tuned output is not present, the electronic circuit will be operating inefficiently. In a transmitter this inefficiency usually manifests itself in the form of excess heat. Excess heat is where the electromechanical stress generally comes from.

Solid-state components like transistors and integrated circuits can run hot for a while without damage but heat will eventually take its toll. In a higher powered transmitter things melt and pop, in a 100 mW unit the circuit starts to lose efficiency internally.

One reason for this is that in order to make electronic components affordable, values are seldom absolute. Affordable parts usually have a component value variance of 5%-20%. If heat damage causes those values to change further, the component values like the Ohms of the resistors or the Farad or voltage ratings of the capacitors, or the breakdown voltage of the diodes or parameters of the ICs start to move outside of the useful range for the circuit in question.

In a 1000-watt unit something would eventually fry or rupture and the circuit would fail outright. In a 100 mW unit you would more likely experience poor sound quality, reduced range or higher noise floor.

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It's not just the wind, unfortunately, it's everything including the water mass in the bodies of the insects that make a nest under your transmitter box :-)

It's all about bandwidth, and the bandwidth of an excessively short antenna tuned with a loading coil (which is all we part15ers can do legally) it frightfully narrow - makes the eye of a needle look like an airplane hanger. This means that the difference between being in tune and being out of tune is just a tiny change in the settings. Long term you'll experience that damage I referred to earlier, but what you'll notice right away is a significant loss in range.

To make matters worse, an AM broadcast band antenna is influenced and affected by anything in the environment with an electromagnetic presence - metal, water, humans and other creatures (AKA bags of water), just about any change in the immediate environment will impact the tuning.

What this means is that when you successfully tune your transmitter and antenna, what you have really done is balance the entire electromagnetic environment of your transmitter and antenna. If ANYTHING changes, you're out of tune again. How much you're out of tune depends on what changed how much. Again, you'll notice range drop precipitously.

The wind load on any antenna will cause the antenna to move and flex. Those movements will subtly change the impedance of the antenna load and your tuning will slowly go away from ideal.

So is it utterly hopeless? No, not at all, and with the Procaster you have all the help you could possibly get - good product and good support, and a super cool and handy tuning meter built right into the unit.

Gerry REALLY knows what he's doing! Gerry knows we need to recheck and retune our transmitters frequently to keep abreast of the changes in the environment around the transmitter to maintain maximum range. Gerry has made that as easy as possible by including everything you need to accomplish that task built right in.

All you need to do is to remember to check you tuning as part of regular maintenance and you'll be operating at maximum range and peak efficiency

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