[Date Prev][Date Next][Thread Prev][Thread Next] - [Date Index][Thread Index][Author Index]

Compare N3IYR 3ft dish and Primstar with 5 1/2 turn helix feed

After two days of experimentation I discovered that my N3IYR 3ft offset dish 
outperforms the Primstar Dish with a 5 1/2 turn helix feed by about 3 
db...this measured by the S meter on the 847....which I know is not that 
accurate...these measurements were made at different MA counts and squint 
angles from 5 to 28 degrees....I hate to show my ignorance but after reading 
in the Handbook.. I cannot figure out how to measure tha impedance at the 
helix feed point...the first turn of my helix is not 1.6mm from the reflector 
as indicated in the mode S book...however about 1 inch from the actual feed 
point...I do have it within the width of a piece of circuit board from the 
surface..I glued a piece of circuit board to reflector..and soldered the 
conductive side of piece of circuit board to the helix....

How do I measure the actual impedance at the feed point of the helix feed..?? 
During experimentation  I compressed the helix several times...without any 
improvement in the signal...

Mike Miller KA5SMA
area coordinator..
Via the amsat-bb mailing list at AMSAT.ORG courtesy of AMSAT-NA.
To unsubscribe, send "unsubscribe amsat-bb" to Majordomo@amsat.org