[Hallicrafters] Poor BCB sensitivty on SX-71

[Roger D. Johnson]

Many manufacturers deliberately reduce sensitivity on
the broadcast band where signals are usually strong.
If you look at the primary of the transformer between
the RF amp and mixer, you will see that it is shunted
with a 100 ohm resistor (R-67). This will knock down
the gain considerably (and also widens the bandwidth).
Also, the input of these older receivers was usually
designed for 300 ohms or thereabout. This gave reasonable
results with whatever antenna was used with it whether
coax fed or an end fed wire.
Congratulations on your restoration. I hope you have many
pleasurable hours of listening.

73, Roger
 
 

73