The 28MHz (10m) Band
Also see my articles in Practical Wireless, Feb 2000 "Getting ready for 10m" and "10m in the Quiet Years" (hopefully publishing later this year)
Introduction to 10m
The 28MHz (10m) amateur allocation spans from 28-29.7MHz. Being this large, there is room for all speech and data modes including AM and FM. In my opinion it is the very best band for amateur radio operation. It is good for both DX and local communications and requires only simple antennas and low powered equipment. If you've never tried 10m operation you've missed some great fun.
DXing on 10m
In sunspot maximum years the 10m band is often wide open for world-wide DX even with QRP power levels and when using the simplest of antennas. At most other times in the sunspot cycle it is open to somewhere in the world during daylight hours although DX is more usually found on the N-S paths rather than E-W. In the quieter years DX may be hard to find due to lack of activity rather than poor conditions. Monitoring the various 10m beacons gives a useful indication of propagation. The usual modes for DX working are USB and CW. In addition, data modes such as PSK31 are becoming increasingly popular around 28.12MHz.
At times, most propagation modes are possible on the 10m band. Most DX contacts are via F2 layer propagation although short skip Sporadic-E is a propagation mode that frequently brings unexpected contacts at high signal strengths especially during the early summer months. Sporadic-E contacts usually range from 300-1000 miles although multi-hop sporadic-E is quite common. Even in sunspot minimum years this can result in transatlantic contacts from Europe to the USA in summer time. It is not that uncommon for multiple modes to be possible. A summer sporadic-E opening can join up with F2 propagation at lower latitudes and some amazing DX then becomes possible when least expected. Another useful mode is aurora which can support DX out to about 1000 miles in higher latitudes at times of auroral disturbances. On 10m auroral contacts on SSB are possible as the phase distortion is less severe than on the 6m or 2m VHF bands. Finally good old tropo openings can support extended local communications up to several hundreds of miles. This can bring surprise range extensions when operating 10m FM mobile for example. Tropo openings on 10m are often at their best around sunrise.
FM operation is centred around 29.6MHz which is used as the calling frequency. Although when the band is not open this is used by many as a frequency to chat on it is courteous to move off this frequency once contact has been established in much the same way that 144.3MHz is used in Europe. There are numerous 10m FM repeaters around the world. These use a -100kHz shift and input frequencies start around 29.5MHz. 10m FM is especially ideal for local communications as ranges up to 25-30 miles are possible with just a few watts to a mobile vertical whip or CB 1/2 eave vertical. DX operation using FM can be fun although the QRM level can be high at times unless you spot an opening at a time when few others have. Many people use converted CB equipment which is inexpensive and in many cases not hard to adapt to 29MHz operation.
10m is one of the few bands on which AM operation is quite common. The band is wide enough to accommodate AM signals that would just not fit on many lower frequency bands. Look between 29-29.1MHz for AM stations. Often AM operators are using lovingly restored AM transmitters that date back to the 1940s, 50s and 60s. The modulation is frequently superb. Listening to 10m AM is like entering a time warp: this is how amateur radio sounded in the 1950s and 1960s when I first became interested in shortwave listening.
I have never used other than the most modest of antennas on 10m. Good results can be achieved with just a vertical or horizontal dipole or with a CB 1/2 wave vertical antenna. These antennas are very small in size (a wire dipole is just over 16 foot long) and have good "neighbour acceptance factor"! Although a small beam would help at times many have found that world-wide DX can be achieved without. Using just an FT817 with 5W SSB I have managed to work over 11000kms using just an indoor Miracle Whip antenna only 56 inches long!
10m is an ideal band for homebrewed equipment and antennas. A simple VXO controlled 1W QRP transmitter with just a handful of parts can be built "ugly" style on a piece of copper laminate in just 30 minutes. Such rigs are capable of working thousands of miles and are enormously satisfying to use. Similarly, a small direct conversion transceiver is not much more difficult. At low power, DSB is a perfectly acceptable mode to use on 10m and there have been several circuits published. Simple verticals and beam antennas are easy enough to fabricate using readily available metalwork from the local DIY shop and can be erected without help, if care is taken.
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