Re: FM Radio Testing x 4


Todd
 

Portable FM radio + inbuilt whip weak signal DX performance is down some 30 to 40 dB relative to a commercially available 8-element rooftop Yagi + sensitive high-end tuner (e.g. Sony XDR tuner). In practice my testing demonstrated that a faint FM signal received on the most sensitive portable radio, translates to a simultaneous noise-free signal on my 8-element rooftop Yagi + XDR-S3HD tuner. This is why I don't use portable radios for FM DXing. However, a portable radio will sometimes produce impressive results in outstanding areas where signal field strengths are massive. But even in these relatively infrequent instances, the portable radio is the weak link in the signal chain. One example is when tropospheric ducting modulates signals to unusually high levels to the extent that New Zealand FM at average 2200 km is received on low gain portable radios.

A portable radio with external antenna input (e.g. PL-390), coupled via coax cable to a collapsible 3-element FM Yagi + portable mast, will produce stronger distant signals.

The medium wave band propagates widely, with some comparisons to the shortwave band. Conversely, the 88-108 MHz FM band is much shorter distance range, and shorter time duration requiring more sophisticated receiving gear. 

Regards,

Todd

http://home.iprimus.com.au/toddemslie/dx.html

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