I offer the following for your consideration. Once upon a time - about 1968 Motorola introduced 4 low noise transistors for audio and low frequency applications. There were th 2N5086, 5087, 5088 and 5089.
The 5086 and 5087 are PNP and the 5088 and 5089 are NPN. They are almost perfect complements to each other. They are still made though the part numbers are now MMBT2N5088L and so on. As of September 2014 I bought and used several of them in a photo transistor preamp for a laser theodolite receiver. They are commonly available from distributor stock. They differ slightly in noise figure and Beta. Since 1970 I have used them in a number of professional applications from DC up to 50 MHz. The latter a 6 channel summing amplifier for a military mapping photo transistor device. These are some of the hottest bi-polar devices known with a specified minimum beta of 150 at 100 uA. The beta is pretty flat up to 10 mA. The current gain bandwidth product varies from a bit less than 50 at 100 uA up to 500 at 10 mA. At 1 mA it is 200. The low frequency noise figure IS specified - 2N5086 3.0 dB MAX (Ic = 20 uA, Vce = 5 v, Rs = 10 K, from 10 Hz to 15.7 kHz) 2N5087 2.0 dB Max, 1.0 dB typical(Ic = 100 uA, Vce = 5V, Rs = 3K, f = 1.0 kHz) Data is provided for the effect of source resistance and Ic on the noise figure. Data for the complementary 2N5088 and 2N5089 is nearly identical. You can look it up. It is all on the data sheet for the original devices and may be found in the "Semiconductor Data Handbook" issued my Motorola in the 1970. the data may also be on the "ON" semiconductor web site among other places. With their relatively low high frequency response (as compared to a 2n2857) you are not risking oscillations up in the the microwave bands where most of you do not have the test gear to find and fix any funny business. This is a really nice calm set of devices and easy to use. I believe that when I bought them last year they were around a buck each. The 5086 and 5087 are PNP and the 5088 and 5089 are NPN. They are still made though the part numbers are now MMBT2N5088L and so on. As of September 2014 I bought and used several of them in a photo transistor preamp for a laser theodolite receiver. They are commonly available from distributor stock. I have not applied them in low noise oscillator applications and have no idea as to their suitability for that. But they are one hell of a transistor family and worth knowing about. Best regards john c roos K6iql spring hill ks _______________________________________________ time-nuts mailing list -- [email protected] To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
