Yes, I swept each of the seven transistors I tried. This is typical, and the gain for the last one, 2N4401, unmarked brand:
0.2 MHz +16.1 dB gain
0.5 MHz +16.3 dB gain
1 MHz +16.3 dB gain
5 MHz +16.1 dB gain
10 MHz +15.8 dB gain
20 MHz +14.9 dB gain
30 MHz +14.0 dB gain
Steve
toggle quoted message
Show quoted text
On 10/9/2024 11:37 AM, Johan Bodin via groups.io wrote:
Steve,
did you measure the frequency response? The properties of the output transformer and the RFC in the base biasing circuit will of course have influence on the frequency response but I am just curious.
73 Johan SM6LKM
Steve Ratzlaff wrote:
I've uploaded to the Files a relatively simple one transistor 50 ohm preamp with +30 dBm OIP3 that can be built using common transistors and used to check your own IMD test set. I tried seven different transistors, three different types, different brands. Use a power supply you can set to 12.0 volts, as IMD is sensitive to supply voltage, to obtain the same results that I got. /g/loopantennas/files/50%20ohm%20Preamp%20with%20+30%20dBm%20OIP3
73,
Steve AA7U
