Timeline for Oscillator amplitude dependent on specific transistor in circuit puzzle (carrier oscillator board repair)
Current License: CC BY-SA 4.0
9 events
| when toggle format | what | by | license | comment | |
|---|---|---|---|---|---|
| Jan 10, 2022 at 11:55 | answer | added | Lehmann Ed | timeline score: 0 | |
| Jul 18, 2021 at 20:56 | answer | added | Bruce Abbott | timeline score: 1 | |
| Jul 18, 2021 at 15:21 | comment | added | glen_geek | Your oscillator is biased near 1mA. 2SC460 (Hitachi) lists power gain at 1mA bias between 13-17 @ 100MHz. That's a VHF transistor. 2SC945 shows GBW of 100 at 1mA bias...at 100MHz it has power gain of 1. That's a general-purpose transistor much like 2N3904. | |
| Jul 18, 2021 at 15:10 | comment | added | A_L | @glen_geek according to the datasheets that I've linked, their fT (gain * BW) products is similar, 230MHz for the 2SC460 and 250MHz for the 2SC945. There are several datasheets that can be found online for both transistors, having slightly different values for fT, but I have never found a datasheet for the 2SC460 that mentions fT to be 1.5GHz | |
| Jul 18, 2021 at 15:09 | comment | added | A_L | @Andyaka here are the links: renesas.com/us/en/document/dst/2sc460-2sc461-datasheet and rcscomponents.kiev.ua/datasheets/2sc945.pdf | |
| Jul 18, 2021 at 13:11 | comment | added | glen_geek | Your Hfe measurements are static, DC measurements. 2SC460 is a high-frequency transistor whose gain*bandwidth product is something like 1500 MHz, while 2SC945 is more like 100 MHz. | |
| Jul 18, 2021 at 11:45 | comment | added | Andy aka | Link to the two data sheets please. | |
| Jul 18, 2021 at 11:42 | review | First posts | |||
| Jul 18, 2021 at 11:45 | |||||
| Jul 18, 2021 at 11:39 | history | asked | A_L | CC BY-SA 4.0 |