1. An amplifier with a 0 dB noise figure would be perfect. 2. Thus, the noise figure of tube amplifiers increases with frequency. 3. The noise figure in this case is 20 dB. 4. In most cases only the noise figure of the first stage need be considered. 5. The total noise factor can then be used to calculate the total noise figure . 6. To obtain low noise figure the impedance of the source can be increased by a transformer. 7. At 800 MHz, tubes like EC8010 have noise figures of about 10 dB or more. 8. To obtain low noise figure , the impedance of the source can be increased by a transformer. 9. From those measurements and the characteristics of the noise source, the noise figure can be calculated. 10. Noise generators are used to test signals for measuring noise figure , frequency response, and other parameters.
