Difference between revisions of "ΜBITX/Power, spurs, and harmonics"
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=== Levelling out power === | === Levelling out power === | ||
| + | [http://ubitx.net/2018/06/11/evening-up-power-output-interim-suggestions-from-allison-kb1gmx/ KB1GMX's fix]: | ||
| + | |||
| + | * Replace the 2N3904s (Q911, Q912, Q92, Q93, Q96, Q97) with 2n2222 (TO18) (using the shortest leads possible). | ||
| + | * Stack 22Ω 1206 SMD resistors parallel to R941, R911, R96, and R942 (for 11Ω each) | ||
| + | * Replace Q90 with BFR106 | ||
| + | * Increase R81 to between 2KΩ and 2.7KΩ | ||
| + | * Change C81 to 470 pf | ||
=== Reducing harmonics === | === Reducing harmonics === | ||
| − | + | [http://ubitx.net/spectral-purity/ Replace the four relays with] | |
| + | * 4 × Axicom D2n 12v relays (model V23105-A5403-A201 | ||
=== Reducing spurs === | === Reducing spurs === | ||
| Line 13: | Line 21: | ||
* 2 × 1210 SMD inductors at 680nH or 681nH | * 2 × 1210 SMD inductors at 680nH or 681nH | ||
| + | |||
| + | === Dummy load watt meter === | ||
| + | Per [https://electronics.stackexchange.com/questions/515069/mimicking-dvm-10-to-11m%ce%a9-input-impedance-on-microcontroller-analogue-input this post of mine]. | ||
| + | |||
| + | * 1 × MCP6021 op amp | ||
Latest revision as of 21:58, 6 August 2020
Contents
Parts and instructions
Levelling out power
- Replace the 2N3904s (Q911, Q912, Q92, Q93, Q96, Q97) with 2n2222 (TO18) (using the shortest leads possible).
- Stack 22Ω 1206 SMD resistors parallel to R941, R911, R96, and R942 (for 11Ω each)
- Replace Q90 with BFR106
- Increase R81 to between 2KΩ and 2.7KΩ
- Change C81 to 470 pf
Reducing harmonics
- 4 × Axicom D2n 12v relays (model V23105-A5403-A201
Reducing spurs
Replace L5 & L7 with
- 2 × 1210 SMD inductors at 680nH or 681nH
Dummy load watt meter
Per this post of mine.
- 1 × MCP6021 op amp
