This & That
CQ100 + QsoNet - Is It Really Amateur Radio? - Mike G4VEC
As it is purely a computer generated internet system, it cannot be defined as being truly amateur radio. But it does have some good points that are worthy of mention. Please consider the following:-1. You have to be a licensed amateur radio operator, and you must submit proof of this by sending an image of your government issued license certificate.2. Once your account is activated, an image of a transceiver will appear on your computer screen. It will be seen that it covers HF radio bands - 80, 40, 20, 15, and 10 meter bands. Computer microphone provides voice modulation. CW mode can also be achieved.3. Band scope shows radio activity within a settable sweep range of 50, 100, 200, and 500 kHz.4. Callsign, QTH, etc are automatically displayed for current transmitting station.What Are The RulesOperators are expected to use normal radio procedure - For example:1. Identify your callsign frequently.2. Always be courteous and respectful. Do not use a frequency that is already in use.3. Do not use voice on the CW portions of the bands.4. Do not engage in commercial activity. No advertising.5. Do not transmit music.So Who Would Want To Use This Internet CQ100 TX ?Your main rig, or antenna develops a fault and you are unable to use it. Assuming you have a computer, you should be able to get help and advice by using the CQ100 'rig'. Perhaps you have financial problems and are unable to afford to repair or replace faulty equipment, but still wish to have contact with fellow hams. You may have just passed an exam which enables you to operate a radio, but as yet cannot afford to buy the necessary equipment, by using the CQ100 rig, you will not fall into bad operating habits, as you are required to use normal radio procedure, and should give one the confidence and experience whenoperating a 'real' transceiver.ConclusionsThe above is my personal opinion but it is to be hoped that it is worthy of consideration. The following link may be of interest:-
The Plain Truth About SWR - Does It Matter? - By The President G4VECWhat is SWR?More correctly VSWR (voltage standing wave ratio) but usually abbreviated to SWR. Expressed as a numerical ratio, e.g.3:1 it is an indication of how well (or badly) our antenna is matched to our transmission line or feeder. Radio amateurs measure it, usually, on a cheerful little SWR bridge bought at the corner shop.The lower the standing wave ratio the better is the match. The ideal SWR would be 1:1 indicating perfect matching. Impossible to achieve in practice, many happy hours can be spent in its pursuit. Like absolute zero temperature we can never quite reach it, only come very close. But how important is it to even come close - say 1.5:1. What are the penalties if we do not? SWR is merely a numerical ratio,so what really concerns us is the effect of a high SWR.......and what is 'high' anyway..........Where SWR is unlikely to matter:Before the days of inexpensive SWR meters; before coaxial cable was in everyday amateur use (yes - there was such a time) there was much less worry about SWR than there is today.It was not that people were unaware of SWR. Rather the reverse, because some twin open wire feeders in common use - the tuned variety - operated happily with enormous SWR's. Yet there was little concern about it. Losses were low and so was feeder radiation. The former because of the design of the feeder, and the latter providing currents were equal and opposite, then the resulting radiation field cancelled out.Here then is one misconception. That a high SWR (anything above 2:1 today) must result in radiation and loss. Take radiation first. Providing currents in the feeders are equal and opposite (and fortunately they usually are) and the spacing of the conductors is small compared to the wavelength ,then the fields will cancel and radiation will be nil. With coaxial cable, providing these currents are kept inside like water in a hosepipe, then again they will not radiate. And they will stay inside providing you do not let them out, for example, by neglecting to use a balun if your antenna feed system needs one.Where we think SWR does matter:Although we talk about SWR and its various numerical values, we are really discussing impedance matching. That is, matching the antenna impedance to the feeder impedance, to the output impedance of the transmitter. The lower the SWR, the better the match with perfection being 1:1.Have a look at the specification for your transceiver, or check the data plate. Its output impedance is usually quoted as 50 ohms. This means your equipment has been designed to 'look into' a resistive load of 50 ohms. if it 'sees' this, then all is well. But suppose the load is 100 ohms, or perhaps 25 ohms. Either will equal an SWR of 2:1 and although we have agreed this is inconsequential in terms of loss in a feeder, we must not assume that your transceiver is happy . Far from it. Again, when discussing SWR and matching, most texts speak in terms of ohms resistance. An antenna, any antenna, which is self resonant, looks like a resistor of a particular value. Examples of matching technique then usually confine themselves to transforming this resistive value into another ,hopefully ending up with the 50 ohms our transmitter needs. But in the real world, antennas are connected to transmitters by feeders. The transmitter 'looking into' the business end of the feeder can see something which is resistive ,but is also pretty certain to include something called reactance. This is the bogey man stuff that detunes our output stage and some transceivers can cater for it, others cannot. Although equipment with valves in the output stage can be forgiving, even these can be mistuned sufficiently by the SWR to not give the full output they are capable of. But worse is to come.............The latest all solid state equipment with its undoubted advantages of compactness, broad banding etc. is most intolerant of high SWR. So much so, that most models have in-built protection circuitry guarding against its consequences. The usual remedy is an automatic reduction in output power as SWR increases. Typically, when the SWR reaches 2:1 then output power is halved.What is needed in all cases, is an impedance matching unit which can cope with resistance, plus reactance, and present it to our transceiver looking like a 50 ohm resistor. Only then shall we get full power out over the maximum bandwidth. Also, remember, a matched antenna system will give much improved reception.
Useful links to e-Ham, QRZ.com etc can be found on the Links page.
Useful Links
Click here: QsoNet - Virtual Ionosphere For Amateur Radio
Further Thoughts and Myths on SWR ? Mike G4VEC ?There is nothing wrong with my antenna, in fact, the SWR is probably better now than when I installed it some years ago?If the above is true, it is time to be concerned. If the SWR is lower than it used to be, the main reason is an increase in losses in the system. Losses represent that portion of energy converted to heat along the line and at the antenna terminals, energy that is no longer available as energy to radiate. As systems get older, cables lose their dielectric material properties, and become lossy. Contacts start to corrode, and a number of other factors point to the fact that it is time for some antenna system maintenance. That is, clean, deoxidize, seal, check for tightness. If no improvement is found, it would be prudent to replace the outdoor coax. .?My meter shows the reflected power to be 25watts. I?m worried about losing that power at the antenna, and the harm it must be doing to my rig.?Is there a need to be concerned? Let?s say you set your rig to exactly 100 watts output. The reflect power reads 25 watts. The forward power will read at least 125 watts, probably a few watts more to account for the cable losses, and your rig will be putting out about 102 watts. The difference is 100 watts. Where is it, and where did the extra forward power come from? The reflected power simply returns to the forward direction and adds to the rig?s power along the line. No need to worry about the rig, since it is not affected by the reflected power (except as the reverse voltage may activate a power reduction circuit) The antenna is receiving and converting 100 watts of power (less only the very small amount changed to heat due to cable losses) A receiving station cannot tell the difference in signal strength between an exactly matched dipole and one running a 10:1 SWR to a parallel feed line and ATU system. The received signal strengths will be the same, assuming the antennas occupied the same transmitting positions with the same propagation conditions. Both antennas converted just about 100 watts of RF energy into radiation. It may take about a dozen cycles for the high SWR station system to build to full power and an equal number to return to zero, but when you have millions of cycles per second to use, those few make no difference to the signal intelligence. So the important point to note here is that by using an ATU, the reflected power arriving back at the ATU is reflected In Phase with the transmitter output, thus increasing the forward power by that amount. This power does not go back into the rig and create heat damage to the PA etc.
Click here: BesserNet Reflectometer
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