TopBand: test osc
Thu, 18 Mar 1999 13:30:41 EST

For testing rx antennas you can build a simple test oscillator.  I used an 
1843 khz quartz clock oscillator.  It costs $4 from Digi-Key, part X103ND,
page 250 of their Jan-Mar 99 catalog #Q991.  Pin 7 ground, Pin 14 is + 5V,
pin 8 is the output for a wire for antenna.  I run the circuit from a 9V
battery, with a 5.1V zener diode to pin 14, fed from +9V with a small
resistor.  The catalog says 15 ma, but mine pulls 3 ma, so I use a 620 ohm
resistor, with 4 ma thru the zener.  If the chip did pull 15 ma, then a 220
ohm resistor would be better.  The zener can be a 1N5231 or IN4733, page 225.
You can request a catalog from  I put the test oscillator out
in the field to test EWE f/b.  On the air tests are better, but we dont hear
JA every day!  I built my circuit on a protoboard using #22 telephone wire
connections.  My "student" N0CKD, Dennis, built one on a board, and put it in
a RS box with an on/off switch.  Both gadgets work well and have helped on
topband rx antenna testing.  There are still some circuits that we can build!  
73 Bob W7LR

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