whistles in receive

Leland Lannoye
 

I am sitting here reading some of this information and studying the new technology.  When I was young (at leas 50 years ago), solid state technologies were either in their infancy or still a dream.  Our rigs were two pieces of equipment, a receiver and a transmitter with a variety of accessories.

Most of our receivers for those of us who were not well heeld in the financial area were of the single conversion genre with an if frequency of 455 kHz.  With little preselection capability, this relegated the ham bands 20 mtrs and above useless with hetrodyne images from frequencies 910 kHz either above or below the desired reception point. There, in that day, were three remedies to fix this. The first two were:

    1.)  add a really selective high gain preselector to tune the offending images out

    2.)  raise the if to something on the order of 1600 kHz which left bandpass selectivity at a substantial disadvantage.

The third option, and the most expensive in its day was double (or, even triple) conversion.  If  you were able to pay the 1958 price of over $300, you were in and there were few difficulties thereafter until the receiver aged and developed some bad shield grounds or worse.  The second or third conversion local oscillator would provide a cornu copia of birdies of one type or another. These included signals that were always there, I know the newer designs with balanced mixers and the like have few of these problems, but, it is worth considering.

An aging ham from way back.


Lee, WA9AOE


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