TopBand: 160 Meter pre-amp and BC rejection

[gary nichols]

I have been receiving quite a bit of mail concerning broadcast rejection
and the necessity of needing additional filtering for BC stations.  Today I
took my own pre-amp and did the following measurements on it:

freq        gain min            gain max

1840       unity (0db)         23 db

1540        -24db               -24db

1000        -46db               -46db

.500         > -60db            > -60db

This clearly shows that the pre-amp with tuned input and tuned output
stages reduces BC stations by a significant amount, depending on the
stations freq. Using the pre-amp at low gain settings can enhance
rejection, or even improve overload by turning off the receiver's internal
pre-amp, and making up the gain with the external amp which add two tuned
stages of rejection.  Thanks for listening and any comments appreciated. 
de gary, kd9sv



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