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Blwikiadmin (talk | contribs) (Created page with "== Homebrew RF Attenuators == file:Atten_30dB_20dV_P1812-720px.jpg === 30 dB Attenuator === * [http://leleivre.com/rf_pipad.html Pi Attenuator Calculator] file:Atten...") |
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+ | == Homebrew RF Attenuators == | ||
+ | [[file:Atten_30dB_20dV_P1812-720px.jpg]] | ||
+ | |||
+ | === 30 dB Attenuator === | ||
+ | |||
+ | * [http://leleivre.com/rf_pipad.html Pi Attenuator Calculator] | ||
+ | |||
+ | [[file:Atten30dB_P116-720px.jpg]] | ||
+ | |||
+ | [[file: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 | ||
+ | |||
+ | [[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]] | ||
+ | |||
+ | === 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 |
Latest revision as of 12:08, 25 November 2021
Contents
Homebrew RF Attenuators
30 dB Attenuator
- 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
- LTSPICE Simulation
20 dB Attenuator
- 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)
- LTSPICE Simulation
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
- Cut "T" Shaped pads
- I used nibbler
- Center fits between connector ground pins
- Glue down pads with Superglue
- Solder center pin with big solder blob
- A bit too high for direct contact
- Verify raised pad does not short to ground
- Solder side resistor(s)
- Leave room for center resistor(s)
- Measure side resistors from pad to ground
- Should match value
- Solder center resistor(s)
- Verify no shorts between centers and ground
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current | 11:23, 25 November 2021 | 1,043 × 495 (42 KB) | Blwikiadmin (talk | contribs) |
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