Difference between pages "ESP32-VGA Rev 2 Assembly Sheet" and "RF Attenuators"

From Land Boards Wiki
(Difference between pages)
Jump to navigation Jump to search
 
 
Line 1: Line 1:
−
[[File:ESP32-VGA_CAD_REV2-bw.PNG]]
+
== Homebrew RF Attenuators ==
  
−
== Parts List ==
+
[[file:Atten_30dB_20dV_P1812-720px.jpg]]
  
−
* [[ESP32-VGA#ESP-32_Module|ESP32 Module]] is marked on bottom "ESP32 DEVKITV1"
+
== Attenuators ==
−
* 0805 resistors are [https://www.ebay.com/itm/free-shipping-5mm-10pcs-2pin-Screw-Terminal-Block-Connector-Pitch-Blue/401412772144?epid=2268620144&hash=item5d7610d130:g:X3UAAOSwqXZZy-vH standard parts]
 
  
−
{| class="wikitable"
+
[[file:Chart_mW_vs_dbM.PNG]]
−
! Qty
 
−
! Value
 
−
! Ref Des
 
−
!
 
−
! Qty
 
−
! Value
 
−
! Ref Des
 
−
|-
 
−
| 4
 
−
| [https://www.mouser.com/ProductDetail/KEMET/C0805C104M5RACTU?qs=sGAEpiMZZMvsSlwiRhF8qsKzCboK%252BzaM5WRFsGtbC9s%3D 0.1uF]
 
−
| C1,C2,C4,C5
 
−
|
 
−
| 1
 
−
| Header, Vert, 1x2
 
−
| H1
 
−
|-
 
−
| 2
 
−
| [https://www.mouser.com/ProductDetail/Taiyo-Yuden/EMK316BJ106KD-T?qs=sGAEpiMZZMs0AnBnWHyRQPSjYu%2Fkbgu8yl4Qxd63iAEnZPPprTwdOQ%3D%3D 10uF]
 
−
| C3,C6
 
−
|
 
−
| 1
 
−
| Header, Vert, 2x4
 
−
| H2
 
−
|-
 
−
| 1
 
−
| [https://www.mouser.com/ProductDetail/Yageo/RT0805FRE07150RL?qs=sGAEpiMZZMu61qfTUdNhGxEjuuBLd0B4fB5OA91vaXU%3D 150 (0805)]
 
−
| R8
 
−
|
 
−
| 1
 
−
| Header, Vert, 1x4
 
−
| H3
 
−
|-
 
−
| 4
 
−
| [https://www.mouser.com/ProductDetail/652-CR0805FX-4220ELF 422 (0805)]
 
−
470
 
−
| R2,R4,R6,R7
 
−
|
 
−
| 1
 
−
| [https://www.ebay.com/sch/i.html?_from=R40&_trksid=m570.l1313&_nkw=5.5mm+x+2.5mm+Plastic+DC+Power+Jack&_sacat=0 Jack, DC, 5.5mm x 2.1mm]
 
−
| J1
 
−
|-
 
−
| 3
 
−
| [https://www.mouser.com/ProductDetail/603-RC0805FR-07845RL 845 (0805)]
 
−
820
 
−
| R1,R3,R5
 
−
|
 
−
| 2
 
−
| Header, 1x6, Rt Ang, (FTDI)
 
−
| J2,J3
 
−
|-
 
−
| 1
 
−
| [https://www.mouser.com/ProductDetail/Texas-Instruments/TXS0104EDR?qs=sGAEpiMZZMsty6Jaj0%252BBBmt4q3EBeXuJ%2F31qI0tuK7Q%3D TXS0104EDR]
 
−
| U2
 
−
|
 
−
| 1
 
−
| [https://www.mouser.com/ProductDetail/523-GMC020080HR Conn, SD Card]
 
−
| J4
 
−
|-
 
−
| 2
 
−
| Header, 1x15, M-F
 
−
| U1
 
−
|
 
−
| 1
 
−
| [https://www.ebay.com/itm/10Pcs-mini-6pin-female-pcb-mount-ps2-jack-mouse-keyboard-plug-connec-CO/312856912531?ssPageName=STRK%3AMEBIDX%3AIT&var=611569754103&_trksid=p2057872.m2749.l2649 MINI-DIN6, PS2 (GRN)]
 
−
| P1
 
−
|-
 
−
| 1
 
−
| [https://www.ebay.com/itm/ESP32-32S-NodeMCU-Arduino-Development-Board-2-4GHz-WiFi-Bluetooth-Dual-Mode/223550838172?hash=item340cab159c&_trkparms=ispr%3D1&enc=AQAEAAADIKvsXIZtBqdkfsZsMtzFbFsbX3WcW5fmB%2Fx7ZbaZTyexexze%2FTjLhzrCnzJPtLhVwcTFqg7L%2FKcAco2lw68ibxnqQQxeJGilW7Vai%2FyyGqjQCITnETrMoM5zCDb2oYSZczmt8xpreIpqykoBWk1jWazgH8XzBKNGATNc1w5qqvHTALF%2BJEQ4fsi%2FYAgVQeO1CFSqzDE3YPOLCDVKk%2BQChIWM9FxSE3SKfVQr2CIWwkhud6xgwUZX%2BC%2FBSaOoIfzKnFL4%2FVU6gqvnenMM1bC6lEP9OaR3NYkn7%2BwbVA88vIPTfp7mK98C0IvMDHx%2FgmrlgJjW%2Bbaf1DBe0%2B7Yx1FNuGmC5GHrsOtbiGdqJZ2lPsd7nFoeTj03sii7fd5p%2FkLPT3D%2F9kry3Din9FtE5h%2Faik5n0uxZVgSj%2FWX4d4zgT%2FnfmjUyV29mLuJUZOh8jjeXVVZ%2FRzZcZ0a2cXGNW%2FetsR4KtjU8qFQ4ZTIDhMz%2FGQwwrI0NZstKC6eFPtyeYc508OE3VkxaELOSmDNbO2i43%2BA8jtr4np2d8Y2az%2F2MnXd3wNBqY1YXP%2BMnGm2aBO6Lsqr7tGo3WgQEVhiEnbtr6CI9%2BtF9Z%2Bk4WJPSJ6rpkb6uQWLHbb73tBx8aZ1wabkjTmItU4LiFo3vFxlmDlciQV3riaTH6cMUKa9XnVdv45BJ3g8HsMQyZTsk155aMIS9QbKieTlyfe1YubcqVtxxVx2ie6SKTdI%2BIYSS3pRA4MD4DB3PLlWTwUvvQIFXUdlHedV4lTK4GWyyJZb1Tlu6MMJeCvtE%2Bh9Zo9ygBzhucV%2FTC4vSHnm%2FgPVuOa5zrkeexMPsqOYOm%2BrN9yuikR7sGbYX4E12CA7jQZfVD1dWXOiHEv1qGPfSU%2FxZ1i9mLAKG3EfYfoxqKXMMICHg5%2BqE%2FMA7pQlJ4IFXy3zXGx%2BFNxtM3FxDoV7q9ltxdrq1C6EBsEu9iT%2FC1F%2FwhmWfuXIK4tqXu1HbVP9Yc4xtDWt%2BPQblZWWK5kyZIeQuOWpEjHPlxAh5Y9idy1hH%2FJEdoOGRtd8NJQB4XrAq7PLlurnSAQWz&checksum=223550838172b8ad12c31d7f4aa896746804e495a3ed ESP32 MODULE]
 
−
| U1
 
−
|
 
−
| 1
 
−
| [https://www.ebay.com/itm/10PCS-MINI-6PIN-FEMALE-PCB-MOUNT-PS2-JACK-mouse-keyboard-plug-connector-Purple/141976500445?hash=item210e7578dd:g:GjMAAMXQC-tTBKMC MINI-DIN6, PS2 (PURP)]
 
−
| P2
 
−
|-
 
−
|
 
−
|
 
−
|
 
−
|
 
−
| 1
 
−
| [https://www.mouser.com/ProductDetail/587-634-015-274-906 CONN, DB15HD, BLUE (VGA)]
 
−
| P3
 
−
|-
 
−
|
 
−
|
 
−
|
 
−
|
 
−
| 1
 
−
| [https://www.mouser.com/ProductDetail/568-NYS354 JACK,, RT ANG, RCA]
 
−
| P4
 
−
|-
 
−
|}
 
  
−
== Sourcing Headers/Pins ==
+
=== 30 dB Attenuator ===
  
−
* "Standard" length is 1x40 or 2x40 pins
+
* [http://leleivre.com/rf_pipad.html Pi Attenuator Calculator]
−
** Cheaper to buy 1x40 or 2x40 and cut off extra pins
+
 
−
* Ebay - [https://www.ebay.com/sch/i.html?_from=R40&_trksid=m570.l1313&_nkw=header+pins+40&_sacat=0&LH_TitleDesc=0&_osacat=0&_odkw=header+pins 1x40 Header pins/sockets]
+
[[file:Atten30dB_P116-720px.jpg]]
−
* Female connectors are expensive on Mouser
+
 
−
** [https://www.ebay.com/sch/i.html?_from=R40&_trksid=p2334524.m570.l1312.R1.TR0.TRC0.A0.H0.Xheader+pins+2x40+female.TRS1&_nkw=header+pins+2x40+female&_sacat=0&LH_TitleDesc=0&_osacat=0&_odkw=header+pins+40+female Ebay has good choices]
+
[[file:30dB_Attenuator.PNG]]
−
* Mouser [https://www.mouser.com/ProductDetail/Harwin/M20-9774046?qs=sGAEpiMZZMs%252BGHln7q6pmzlZUuX%2F53qjJbj%2FQ1pG9jE%3D 1x40 pin straight headers]
+
 
−
* Mouser [https://www.mouser.com/ProductDetail/Harwin/M20-9754046?qs=sGAEpiMZZMs%252BGHln7q6pmzlZUuX%2F53qjVp2YK3gPzB8%3D 1x40 right angle pin headers]
+
* Built
−
* Mouser [https://www.mouser.com/ProductDetail/3M-Electronic-Solutions-Division/2380-5121TG?qs=sGAEpiMZZMs%252BGHln7q6pmwu5ra4CY41i6yhE8n6mBfA%3D 2x40 right angle pin headers]
+
** Standard 5% resistor values
 +
** R1 = 820 in parallel with 22K = 790.6 ohms
 +
** R2 = 2 paralleled 120 Ohm 1/4W resistors paralleled with 470 ohms = 53.2 ohms
 +
** Flat from 0-30 MHz
 +
** Measured attenuation is flat
 +
*** -30.01dB at 1 MHz
 +
*** -30.24dB at 30 MHz
 +
** Input Impedance - 53.1 ohms, 21.3nF
 +
** SWR 1.06
 +
** 1/2W max (5VDC max, 0 ohm source)
 +
 
 +
* NanoVNA scan data
 +
 
 +
[[file:30dB_Attenuator_NanoVNA_Setup_Curve_900MHz.PNG]]
 +
 
 +
[[file:30dB_Attenuator_NanoVNA_Data_900MHz.PNG]]
 +
 
 +
* LTSPICE Simulation
 +
 
 +
[[file:LTSPice_30dB.PNG]]
 +
 
 +
=== 20 dB Attenuator ===
 +
 
 +
[[file:Atten_20dB_P115-720px.jpg]]
 +
 
 +
[[file:20dB_Attenuator.PNG]]
 +
 
 +
* Build
 +
** Standard 5% resistor values
 +
** R1 = 2 of 510 in parallel also in parallel with 8.2K = 247.3 ohms
 +
** R2 = 2 paralleled 150 Ohm 1/2W resistors paralleled with 330 ohms = 61.11 ohms
 +
** Flat from 0-30 MHz
 +
** Measured attenuation is flat
 +
** Input Impedance - tbd ohms, tbd nF
 +
** SWR tbd
 +
** 1W max (8.6 V max, 0 ohm source)
 +
 
 +
[[file:20dB_Attenuator_NanoVNA_Setup_Curve_900MHz.PNG]]
 +
 
 +
[[file:20dB_Attenuator_NanoVNA_Data_900MHz.PNG]]
 +
 
 +
* LTSPICE Simulation
 +
 
 +
[[file:LTSPice_20dB.PNG]]
 +
 
 +
=== 10 dB Attenuator ===
 +
 
 +
[[file:Atten_10dB_P115-720px.jpg]]
 +
 
 +
[[file:10dB_Attenuator.PNG]]
 +
 
 +
* Build
 +
** Standard 5% resistor values
 +
** R1 = 2 of 150 in parallel also in parallel with 1.5K = 71.43 ohms (0.3% error)
 +
** R2 = 3 of 330 Ohm 1/4W parallel resistors paralleled with 810 ohms = 96.85 ohms (0.62% error)
 +
** Flat from 0-30 MHz
 +
** Measured attenuation is flat
 +
** Input Impedance - tbd ohms, tbd nF
 +
** SWR tbd
 +
** 3/4W max (9.1 V max, 0 ohm source)
 +
 
 +
[[file:10dB_Attenuator_NanoVNA_Setup_Curve_900MHz.PNG]]
 +
 
 +
[[file:10dB_Attenuator_NanoVNA_Data_900MHz.PNG]]
 +
 
 +
* LTSPICE Simulation
 +
 
 +
[[file:LTSPice_10dB.PNG]]
 +
 
 +
=== Attenuator Construction ===
 +
 
 +
* Single side copper clad PCB
 +
** Approx 2"x1"
 +
* Clean with steel wool
 +
* Solder SMA connectors
 +
** Use large alligator clips to hold while soldering
 +
** Solder on sides only
 +
 
 +
[[file:Atten_01_SMAs_720px.jpg]]
 +
 
 +
* Cut "T" Shaped pads
 +
** I used nibbler
 +
* Center fits between connector ground pins
 +
* Glue down pads with Superglue
 +
 
 +
[[file:Atten_02_Pads_720px.jpg]]
 +
 
 +
* Solder center pin with big solder blob
 +
** A bit too high for direct contact
 +
* Verify raised pad does not short to ground
 +
 
 +
[[file:Atten_03_Solder CenterPads_720px.jpg]]
 +
 
 +
* Solder side resistor(s)
 +
* Leave room for center resistor(s)
 +
 
 +
[[file:Atten_04_Solder Side_Resistors_720px.jpg]]
 +
 
 +
* Measure side resistors from pad to ground
 +
* Should match value
 +
* Solder center resistor(s)
 +
 
 +
[[file:Atten_05_Solder Center_Resistors_720px.jpg]]
 +
 
 +
* Verify no shorts between centers and ground
 +
 
 +
== References ==
 +
 
 +
<video type="youtube">A5gGeV7CiQ0</video>

Revision as of 11:50, 7 September 2021

Homebrew RF Attenuators

Atten 30dB 20dV P1812-720px.jpg

Attenuators

Chart mW vs dbM.PNG

30 dB Attenuator

Atten30dB P116-720px.jpg

30dB Attenuator.PNG

  • Built
    • Standard 5% resistor values
    • R1 = 820 in parallel with 22K = 790.6 ohms
    • R2 = 2 paralleled 120 Ohm 1/4W resistors paralleled with 470 ohms = 53.2 ohms
    • Flat from 0-30 MHz
    • Measured attenuation is flat
      • -30.01dB at 1 MHz
      • -30.24dB at 30 MHz
    • Input Impedance - 53.1 ohms, 21.3nF
    • SWR 1.06
    • 1/2W max (5VDC max, 0 ohm source)
  • NanoVNA scan data

30dB Attenuator NanoVNA Setup Curve 900MHz.PNG

30dB Attenuator NanoVNA Data 900MHz.PNG

  • LTSPICE Simulation

LTSPice 30dB.PNG

20 dB Attenuator

Atten 20dB P115-720px.jpg

20dB Attenuator.PNG

  • Build
    • Standard 5% resistor values
    • R1 = 2 of 510 in parallel also in parallel with 8.2K = 247.3 ohms
    • R2 = 2 paralleled 150 Ohm 1/2W resistors paralleled with 330 ohms = 61.11 ohms
    • Flat from 0-30 MHz
    • Measured attenuation is flat
    • Input Impedance - tbd ohms, tbd nF
    • SWR tbd
    • 1W max (8.6 V max, 0 ohm source)

20dB Attenuator NanoVNA Setup Curve 900MHz.PNG

20dB Attenuator NanoVNA Data 900MHz.PNG

  • LTSPICE Simulation

LTSPice 20dB.PNG

10 dB Attenuator

File:Atten 10dB P115-720px.jpg

10dB Attenuator.PNG

  • Build
    • Standard 5% resistor values
    • R1 = 2 of 150 in parallel also in parallel with 1.5K = 71.43 ohms (0.3% error)
    • R2 = 3 of 330 Ohm 1/4W parallel resistors paralleled with 810 ohms = 96.85 ohms (0.62% error)
    • Flat from 0-30 MHz
    • Measured attenuation is flat
    • Input Impedance - tbd ohms, tbd nF
    • SWR tbd
    • 3/4W max (9.1 V max, 0 ohm source)

File:10dB Attenuator NanoVNA Setup Curve 900MHz.PNG

File:10dB Attenuator NanoVNA Data 900MHz.PNG

  • LTSPICE Simulation

LTSPice 10dB.PNG

Attenuator Construction

  • Single side copper clad PCB
    • Approx 2"x1"
  • Clean with steel wool
  • Solder SMA connectors
    • Use large alligator clips to hold while soldering
    • Solder on sides only

Atten 01 SMAs 720px.jpg

  • Cut "T" Shaped pads
    • I used nibbler
  • Center fits between connector ground pins
  • Glue down pads with Superglue

Atten 02 Pads 720px.jpg

  • Solder center pin with big solder blob
    • A bit too high for direct contact
  • Verify raised pad does not short to ground

Atten 03 Solder CenterPads 720px.jpg

  • Solder side resistor(s)
  • Leave room for center resistor(s)

Atten 04 Solder Side Resistors 720px.jpg

  • Measure side resistors from pad to ground
  • Should match value
  • Solder center resistor(s)

Atten 05 Solder Center Resistors 720px.jpg

  • Verify no shorts between centers and ground

References

Retrieved from "http://land-boards.com/blwiki/index.php?title=ESP32-VGA_Rev_2_Assembly_Sheet&oldid=8642"