[time-nuts] HP58504A antenna

[Bruce Griffiths]

Correction:
Resistor values used are probably:

100 = 10 ohms
560 = 56 ohms or is it 680 = 68 ohms?
101 = 100 ohms
121 = 120 ohms
181 = 180 ohms
221 = 220 ohms
271 = 270 ohms



Thus the total resistance from the 5V supply to the output terminal of 
the input device is actually = 220 + 10 + 10 = 240 ohms.
Equivalent resistance from  input device "source" terminals to ground = 
90 ohms.
Voltage divider for Vcc of MMIC is 56 ohms from 5V is series with 270 
ohms to ground nominal current ~ 15mA + 6mA? for MMIC, total ~ 21mA.
Input device if shorted would have a current drain of 5V/(90+220 + 10 + 
10) ~  15mA.

Thus measuring the dc output of the input device and/or measuring its 
power supply current is required to assist diagnosis.
Some pHEMT devices have an absolute drain source voltage limit as low as 
3V so the operating drain source voltage of the input device may only be 
1/2 that.
Typical MMICs have a somewhat larger dc voltage on the output.

Bruce