ΜBITX/Power, spurs, and harmonics: Difference between revisions
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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 02:58, 7 August 2020
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
