Difference between revisions of "ΜBITX/Power, spurs, and harmonics"

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(Created page with "== Parts and instructions == === Levelling out power === === Reducing harmonics === * http://ubitx.net/spectral-purity/ === Reducing spurs === [http://ubitx.net/2018/10/...")
 
(Parts and instructions)
 
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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).
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* Stack 22Ω 1206 SMD resistors parallel to R941, R911, R96, and R942 (for 11Ω each)
 +
* Replace Q90 with BFR106
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* Increase R81 to between 2KΩ and 2.7KΩ
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* Change C81 to 470 pf
  
 
=== Reducing harmonics ===
 
=== Reducing harmonics ===
  
* http://ubitx.net/spectral-purity/
+
[http://ubitx.net/spectral-purity/ Replace the four relays with]
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* 4 × Axicom D2n 12v relays (model V23105-A5403-A201
  
 
=== Reducing spurs ===
 
=== Reducing spurs ===
  
[http://ubitx.net/2018/10/10/rajs-second-spurs-mod-simpler-again/ Replace L5 & L7]
+
[http://ubitx.net/2018/10/10/rajs-second-spurs-mod-simpler-again/ Replace L5 & L7] with
  
Replace L5 & L7 with
 
 
* 2 × 1210 SMD inductors at 680nH or 681nH
 
* 2 × 1210 SMD inductors at 680nH or 681nH
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 +
=== Dummy load watt meter ===
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Per [https://electronics.stackexchange.com/questions/515069/mimicking-dvm-10-to-11m%ce%a9-input-impedance-on-microcontroller-analogue-input this post of mine].
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* 1 × MCP6021 op amp

Latest revision as of 21:58, 6 August 2020

Parts and instructions

Levelling out power

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

Replace the four relays with

  • 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