[Home] [Radio Page] [Web links] [Interests] [Location] [Personal] [Aerials] [1.933 PAGE]

 

Page 3

 
 
 
2. The Transceiver


Some HF rigs make for better DX than others, for instance an FT1000MP would probably work more DX  than an FT757 with the same antenna setup. When choosing a rig you need to be concerned primarily with the RX side of things and should check out manufacturers specifications such as sensitivity and selectivity. You also need to choose a rig that will perform well on the noisy low bands, particularly on 40m where intermediation may arise from the nearby broadcast stations in Europe. A good test for anyone in Europe is to listen to the voice allocations on 40m for the US (when the band is open of course). A good rig will pick out ham stations in amongst the splatter and intermediation of broadcast stations. It is also very useful if the rig has narrow filters fitted for both SSB and CW (unfortunately you often have to pay more for these!) and an IF shift control. DSP can also help with noise reduction and filtering and if not included can be purchased as an add-on. 

Having chosen a rig that gives you optimum performance on receive and an effective antenna system you can now turn your attention to the transmit side of things. While many stations will simply go out and purchase or build a beefy linear amp, for the town and city dweller such an option is often not feasible due to interference concerns. With CW,  most of the time high power is not needed and you can get by with the standard 100W or less. 

SSB talk power

For SSB the aim should be to increase the average 'talk power' of the radio. If you look at the output of an SSB radio on a power meter while talking into the mike, you will see that the power is not constant and can vary widely, peaking at maximum only occasionally (this is  a rough guide as an analogue meter cannot accurately respond to the SSB power fluctuations and you will more than likely not get a true indication of the peak talk power). You can increase the average power and the peak power by using some form of speech processing such as clipping or compression. Many rigs have built in speech processors that increase the talk power considerably. For those that do not, the use of an external processor is recommended although care should be taken to ensure that the rig is not overdriven or distortion may result. Often the use of a preamplifier microphone in conjunction with speech processing will boost the talk power even more.

 

 

Page 3 of 10

   

[Home] [Radio Page] [Web links] [Interests] [Location] [Personal] [Aerials] [1.933 PAGE]