updated 12-08-08

Yaesu 102 Factoids

     The FT 102 was designed by the same fellow who later designed the receiver for the 1000D. The receivers are basically identical until the last IF where the 1000D incorporates the DSP functions. In fact the 8 MHz IF frequencies are identical and both radios incorporate variable IF Shift, Width and Notch filters in the same way. All three of those controls are only found in the flagship radio of each manufacturer since they are costly to install in the IF chain.  

     IF filtering is superior to DSP filtering since IF filtering affects the AGC loop and DSP filtering is usually only in the (post detection) audio loop. This means that notching a carrier in the SSB mode by a DSP mechanism still leaves the effects of that carrier in the IF circuitry and consequently that signal's deleterious interfering effect on AGC functioning. With IF filtering the signal is removed from the IF stage and therefore the interfering signal's effects on the characteristics of the IF and AGC circuitry are also eliminated.

     Are you aware that if you have an auto notch DSP filter you cannot use it in CW because it will track the loudest tone?  On the other hand IF notch filtering is good in any mode.
     The third order intercept in the 102 as measured by QST labs in October of 1983 was +19.5 dBM. That is noteworthy because for the 20 year period from 1983 to 2003 no other radio could best that performance. Even up until today most radios can't come close to that performance and if they do they are in the thousands of dollars range

     The 102 utilizes three 6146B tubes for the finals. This enables the 102 to key down 150 to 180 watts in CW and over 200 Watts peak envelope power in SSB. Unlike transistor finals, PEP can be higher than key down powerwith tube finals because the High Voltage capacitors charge to a higher voltage during the pauses of SSB between words and syllables. This is also responsible for the fact that the 102 when properly adjusted can yield 110% modulation in AM without clipping or splatter but transistor finals in today's radios just can't do that because of their power supply characteristics.  Todays trasistor final radios run about 50%~60% modulation in order to get a better carrier output.

     Did you know that the percentage of AM modulation is responsible for your apparent loudness and the carrier or unmodulated power is responsible for quieting the background noise? The best situation for getting thru and being copied is at 100% or slightly greater modulation.

     The 102 does not have a synthesizer in the VFO. Therefore reciprocal mixing products, resulting from synthesizer noise mixing with strong signals above and below the listening frequency, will have no effect on the listening frequency.

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