Hi alll,
This is a repost from another board. I did not receive any useful comments regarding this so I hope someone here can verify or refute my data.
I have done some tests on my Ramsey AM-25 and regardless of the setting of R23, I cannot achieve compliance with part 15 which limits the input power to the RF final amplifier to 100 mW.
Adjusting the test point voltage to 7.1 volts (according to the manual) and taking measurements with no antenna or load resulted in the following:
Hi alll,
This is a repost from another board. I did not receive any useful comments regarding this so I hope someone here can verify or refute my data.
I have done some tests on my Ramsey AM-25 and regardless of the setting of R23, I cannot achieve compliance with part 15 which limits the input power to the RF final amplifier to 100 mW.
Adjusting the test point voltage to 7.1 volts (according to the manual) and taking measurements with no antenna or load resulted in the following:
VDC at R34/C23 junction = 7.1 VDC.
Voltage across R34 = 2.95 V.
Current in to the final amp = 2.95V/10 ohms = 295 mA.
Voltage from Q3 drain to gnd. = 1.2 VDC.
Power into Q3 = Vds x Ids = 295 mA. x 1.2 Vdc = 354 mW.
The minimum voltage at the junction of R34 and C23 that I can get adjusting R23 is 4.71 volts. This gives a voltage drop across R23 = 1.78 Vdc which gives a Q3 current of 1.78V/10ohms = 178 mA. The voltage from Q3 drain to gnd. is 1.1 volts. The power into the final Q3 is 178 mA. x 1.1 V = 196 mW. at the minimum setting of R23. The instrumentation used is a HP E2373A DVM.
Can anyone else, including the good people at Ramsey Electronics, verifiy this?
Neil