Topband: "Thinking out loud"

[GALE STEWARD]

Years ago at the W3GM M/M station, Gerry had several crystal filters (50 ohm Z input & output) in the 40M RX path. As I recall, these were about 20-30 khz wide (each) and were of slightly different center frequencies so that most of the 40M CW band could be covered.
I DO remember that they worked very well. I never saw one for 160.
73, Stew K3ND

      From: K1FZ-Bruce <k1fz at myfairpoint.net>
 To: Topband <topband at contesting.com> 
 Sent: Thursday, December 22, 2016 3:41 PM
 Subject: Topband: "Thinking out loud"
   

 
We know that limiting the noise pick up from more directions of an antenna we can usually hear better. We also know  if we limit the noise from a receiver IF we can hear less noise, and better yet, if we
have a roofing filter earlier in the receiver we can eliminate even more noise  in relationship to the wanted  signals. 
 
What if we take it a step further, could we limit the band-with of the antenna signal with a crystal lattice for 160 meters before the receiver. 
Years ago I played  around with a single crystal at the input of an old tube type receiver. It was remarkable what I could hear on 40 meters, on what seemed to be one frequency. 
 
73
Bruce-k1fz
http://www.qsl.net/k1fz/beverage_antenna.html
 
 
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