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− | == Kits and Parts Universal Filter Board ==
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− | * [https://kitsandparts.com/lpf.1.5.php 7-pole Universal Low Pass Filter for HF] - Kits and Parts webpage
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− | ** $4 PCB
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− | ** Handles toroid inductor sizes up to T80
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− | *** 125W power
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− | ** 0.2" lead spacing for caps
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− | ** (4) 4-40 mounting holes
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− |
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− | === CWAZ filter ===
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− | * [https://kitsandparts.com/PCBs/LPF/filter1.pdf 2nd-Harmonic-Optimized LPFs by By Ed Wetherhold, W3NQN]
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− | ** Much better performance than standard 3C/3L filter at 2nd harmonic
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− | ** Only needs one additional capacitor across center inductor
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− | ** Other L/C values are a bit different to compensate
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− |
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− | === Other References and Topologies ===
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− | * [https://kitsandparts.com/PCBs/LPF/filter0.pdf Introduction to LPFs by Paul Hardin, NA5N]
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− | * [https://kitsandparts.com/PCBs/LPF/filter2.pdf 7 Element Chebyshev standard value capacitor LPFs]
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− | * [https://rf-tools.com/lc-filter/ LC Filter Design Tool]
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− | * [https://www.66pacific.com/calculators/toroid-coil-winding-calculator.aspx Toroid Coil Winding Calculator]
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− |
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− | === K&P Schematic ===
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− | [[file:LPF.1.5.sch.png]]
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− |
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− | === K&P PCB ===
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− | [[file:LPF.1.5.pcb.png]]
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− |
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− | == CWAZ 40M, 7 MHz Filter ==
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− | * Based on [https://kitsandparts.com/PCBs/LPF/filter1.pdf 2nd-Harmonic-Optimized LPFs by By Ed Wetherhold, W3NQN] - Built this one
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− |
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− | === SPICE Simulation ===
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− | * [https://github.com/land-boards/lb-boards/tree/master/HamRadio/BUTTER07/DOCS/Spice_Sims GitHub repo]
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− | * -6 dB at 7 MHz
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− | * -68 dB at 1st harmonic (14 MHz)
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− | * -75 dB at 2nd harmonic (21 MHz)
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− | [[file:CWAZ_LowPass7MHz_SPICE.png]]
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− | [[file:CWAZ_LowPass_Values.PNG]]
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− |
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− | === T37-2 Inductors ===
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− | * [http://toroids.info/T37-2.php T37-2 Toroid Specs and turns calculator]
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− | ==== INDUCTANCE - L1, L3 ====
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− | * Desired: 1.34 uH
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− | * Calculated: 1.3 uH (97% of desired) Turns required: 18
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− | * CORE
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− | * Part number: T-37-2 (Red)
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− | * Frequency Range: 1 to 30 MHz
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− | * u: 10
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− | * AL: 40 uH/100 turns
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− |
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− | ==== INDUCTANCE - L2 ====
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− | * Desired: 1.22 uH
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− | * Calculated: 1.2 uH (95% of desired) Turns required: 17
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− | * CORE
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− | * Part number: T-37-2 (Red)
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− | * Frequency Range: 1 to 30 MHz
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− | * u: 10
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− | * AL: 40 uH/100 turns
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− |
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− | === Measured on NanoVNA ===
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− | * 7 MHz LP filter
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− | * Built with junk box low voltage ceramic disc caps
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− | [[file:LowPass7MHz_NanoVNA.png]]
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− | == Rebuild - Higher Power ==
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− | * T80-2 Inductors
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− | ** Larger gauge wire
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− | ** Integer turns values
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− | ** [http://toroids.info/T80-2.php T80-2 Toroid Specs and turns calculator]
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− | [[file:Toroid_1.24uH_15T.PNG]]
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− | [[file:Toroid_1.41uH_16T.PNG]]
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− | === Simulation ===
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− | [[file:CWAZ_LowPass7MHz_SPICE_IntegerTurnsInd.png]]
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− | === Measured with NanoVNA ===
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− | * Excellent performance!!!
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− | * 7 MHz
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− | ** S21 = -1.55 dB
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− | ** VSWR = 1.008
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− | * 14 MHz - 1st harmonic
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− | ** S21 = -55.8 dB
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− | ** VSWR = 5.181
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− | * 21 MHz - 2nd harmonic
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− | ** S21 = -69 dB
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− | ** VSWR = 15.225
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− | [[file:CWAZ_7MHZ_NANOVNA_125W_PLOTS.PNG]]
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− | [[file:CWAZ_7MHZ_NANOVNA_125W_DATA.PNG]]
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− |
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− | == CWAZ - 20M, 14MHz LP Filter ==
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− | * SPICE Simulation
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− | [[file:CWAZ-20M-SPICE.PNG]]
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− | * Toroid T80-2
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− | [[file:ind-680nH.PNG]]
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− | [[file:ind-608nH.PNG]]
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− | * T80-2 has Optimum Resonant Circuit Range for highest Q and lowest core loss
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− | ** 250 KHz - 10 MHz
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− | * T80-6 has better characteristics
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− | ** Optimum Resonant Circuit Range for highest Q and lowest core loss
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− | ** 3 MHz - 40 MHz
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− | * Don't have any T80-6 but I do have T37-6
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− | [[file:T37-6_Ind-608nH.PNG]]
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− | [[file:T37-6_Ind-680nH.PNG]]
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− | === NanoVNA caps ===
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− | [[file:CWAZ-20M-NanoVNA-data.PNG]]
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− | [[file:CWAZ-20M-NanoVNA-plot.PNG]]
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− | == Ceramic Disc Caps ==
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− |
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− | * High voltage quality caps
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− | ** Ceramic - should these be silver mica caps?
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− | ** Ceramic caps are 10x cheaper than silver mica caps
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− | *** 100pF, Silver Mica cap, P/N: [https://www.mouser.com/ProductDetail/Cornell-Dubilier-CDE/CDV16FF101JO3F?qs=tNDx7qEChkcFgJ1eZKwb4g%3D%3D CDV16FF101JO3F], $1.40 (per, qty 10)
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− | *** 100pF, Ceramic cap, P/N: CC45SL3AD101JYNNA, $0.14 (per, qty 10)
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− | ** Will the ceramic caps cause [https://e2e.ti.com/blogs_/archives/b/precisionhub/posts/stress-induced-outbursts-microphonics-in-ceramic-capacitors-part-1 Microphonics] or is that only an issue in gain stages?
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− | *** SL caps are single layer
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− |
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− | {| class="wikitable"
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− | ! Capacitance (pF)
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− | ! Mfr. #
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− | ! Manufacturer
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− | ! Description
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− | |-
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− | | 10
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− | | S100K33SL0R63K7R
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− | | Vishay
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− | | Ceramic Disc Capacitors 10pF 3000V 10% SL0 7.5mm LS
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− | |-
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− | | 33
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− | | CC45SL3AD330JYNNA
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− | | TDK
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− | | Ceramic Disc Capacitors D: 5.5mm 1kV 33pF SL 5% LS:5mm
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− | |-
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− | | 47
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− | | CC45SL3AD470JYVNA
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− | | TDK
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− | | Ceramic Disc Capacitors D: 5.5mm 1kV 47pF SL 5% LS:5mm
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− | |-
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− | | 82
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− | | CC45SL3AD820JYNNA
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− | | TDK
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− | | Ceramic Disc Capacitors D: 6mm 1kV 82pF SL 5% LS:5mm
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− | |-
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− | | 100
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− | | CC45SL3AD101JYNNA
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− | | TDK
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− | | Ceramic Disc Capacitors D: 6.5mm 1kV 100pF SL 5% LS:5mm
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− | |-
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− | | 120
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− | | CC45SL3AD121JYNNA
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− | | TDK
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− | | Ceramic Disc Capacitors D: 7mm 1kV 120pF SL 5% LS:5mm
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− | |-
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− | | 200
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− | | S201K33S3NN63L6R
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− | | Vishay
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− | | Ceramic Disc Capacitors 200PF 1KV 10%
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− | |-
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− | | 270
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− | | CC45SL3AD271JYVNA
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− | | TDK
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− | | Ceramic Disc Capacitors D: 9mm 1kV 270pF SL 5% LS:5mm
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− | |-
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− | | 330
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− | | S331K33Y5PR63K7R
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− | | Vishay
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− | | Ceramic Disc Capacitors 330pF 3000V 10% Y5P 7.5mm LS
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− | |-
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− | | 390
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− | | CC45SL3AD391JYVNA
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− | | TDK
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− | | Ceramic Disc Capacitors D: 10.5mm 1kV 390pF SL 5% LS:5mm
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− | |-
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− | | 470
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− | | D471K20Y5PH6UJ5R
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− | | Vishay
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− | | Ceramic Disc Capacitors 470pF 100V 10%
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− | |-
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− | | 680
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− | | S681K29Y5PN63J5R
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− | | Vishay
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− | | Ceramic Disc Capacitors 680pF 1000V 10% Y5P 5.0mm LS
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− | |-
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− | |}
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