Difference between pages "RF Attenuators" and "RF-Amp"

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== Purchased Attenuators ==
+
[[File:RF-Amp_Front.png]]
  
−
=== Programmable Attenuator ===
+
== RF Amplifier Features ==
  
−
* [[PE4302 RF Attenuator|PE4302 RF Attenuator board in my enclosure design]]
+
* From [https://zl2ctm.blogspot.com/2020/11/go-qrp-portable-ssb-rig.html Charlie Morris' (ZL2CTM) Go QRP Portable SSB Rig]
 +
** Solid State Design for the Radio Amateur?
 +
* +22 dB gain
 +
* Input connectors: SMA or BNC
 +
* 49x49mm card
 +
* 4x 4-40 mounting holes
  
−
[[file:PE4302_P1833-720px.jpg]]
+
== RF Amplifier Design ==
  
−
=== Triple Attenuator ===
+
=== Schematic ===
  
−
* [[0/10/20/30 dB Attenuator]]
+
[[file:RF_Amp_Schematic-4.PNG]]
  
−
[[file:ATTEN4_CHINA_PCB.PNG]]
+
=== DC Operating Point ===
  
−
== Homebrew RF Attenuators ==
+
* Ice = 10 mA
 +
* Ve = 0.1 * Vcc = 1.2V
  
−
[[file:Atten_30dB_20dV_P1812-720px.jpg]]
+
=== Input/Output Transformer ===
−
=== 30 dB Attenuator ===
 
  
−
* [http://leleivre.com/rf_pipad.html Pi Attenuator Calculator]
+
==== FT37-43 Toroid ====
  
−
[[file:Atten30dB_P116-720px.jpg]]
+
* [http://toroids.info/FT37-43.php FT37-43]
 +
* Wideband Transformers 5 - 400 MHz
 +
* Power Transformers 0.5 - 30 MHz
 +
* 10 turns = 35uH
  
−
[[file:30dB_Attenuator.PNG]]
+
[[file:FT37-43_10_Turns.PNG]]
  
−
* Built
+
==== Tracks ====
−
** 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:RF-Amp-tracks.PNG]]
  
−
[[file:30dB_Attenuator_NanoVNA_Setup_Curve_900MHz.PNG]]
+
==== Input Transformer ====
  
−
[[file:30dB_Attenuator_NanoVNA_Data_900MHz.PNG]]
+
** Input Transformer (T1 on Charlie's - T2 on this board)
 +
***  50:75.8 Ohms = 1 : 1.23 turns ratio
 +
**** 9 turns primary, 11 turns on secondary
  
−
* LTSPICE Simulation
+
[[file:RF-Amp-T2.PNG]]
  
−
[[file:LTSPice_30dB.PNG]]
+
==== Output Transformer ====
  
−
=== 20 dB Attenuator ===
+
** Output transformer (T2 on Charlie's - T1 on this board)
 +
*** 200:50 Ohms = 2:1 turns ratio
 +
*** 10 turns primary (on transistor collector), 5 turns secondary (towards output)
  
−
[[file:Atten_20dB_P115-720px.jpg]]
+
[[file:RF-Amp-T1.PNG]]
  
−
[[file:20dB_Attenuator.PNG]]
+
== LT Spice Simulation ==
  
−
* Build
+
* [https://github.com/land-boards/lb-boards/blob/master/HamRadio/RF-Amp/LTSpice/2n3904%20amp.asc LTspice Simulation] - GitHub source file
−
** 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]]
+
=== Transformers ===
  
−
[[file:20dB_Attenuator_NanoVNA_Data_900MHz.PNG]]
+
[[File:RF-AMP-LTSPICE_XFMRS.PNG]]
  
−
* LTSPICE Simulation
+
== Charlie Morris Design ==
  
−
[[file:LTSPice_20dB.PNG]]
+
* From Charlie's notes with mods for my use
 +
** [https://zl2ctm.blogspot.com/2020/11/go-qrp-portable-ssb-rig.html Charlie Morris' (ZL2CTM) Go QRP Portable SSB Rig]
 +
* [https://www.mouser.com/datasheet/2/308/1/2N3903_D-2310199.pdf 2N3904 data sheet]
  
−
=== 10 dB Attenuator ===
+
=== Beta DC ===
  
−
[[file:Atten_10dB_P115-720px.jpg]]
+
* Geometric mean min/max beta at operating current
 +
** =sqrt(100*300) = 173
  
−
[[file:10dB_Attenuator.PNG]]
+
=== Beta AC ===
  
−
* Build
+
* Gain bandwidth product divided by operating frequency
−
** Standard 5% resistor values
+
** Assume operating frequency of 10 MHz (my IF is actually at 9 MHz)
−
** R1 = 2 of 150 in parallel also in parallel with 1.5K = 71.43 ohms (0.3% error)
+
** = 300/10 = 30
−
** 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]]
+
=== DC Operating Point ===
  
−
[[file:10dB_Attenuator_NanoVNA_Data_900MHz.PNG]]
+
* CE current 10 mA
 +
** V(emitter resistor) = 1/10 Vcc = 1.2V
 +
*** R(emitter resistor) = 1.2V/0.01A = 120 ohms
 +
* VCE = 0.7V
 +
* V(emitter) = 1.2V
 +
* V(base) = V(emitter) + VCE = 1.9V
 +
* Assume current in biasing resistors = 10x current needed by DC beta
 +
** 10 mA in C-E, beta DC less = 10 mA/173 = 48 uA
 +
** 10x the current in the biasing resistors = 480 uA
 +
* R2 is 1.9V at 480 uA = 3.9K use 3.3K
 +
* R1 sources current to R2 and BE junction
 +
** Voltage = Vcc (12V) - 1.9V = 10.1V
 +
** Current = 480 uA + 48 uA = 528 uA
 +
** R1 = 10.1 / .528 mA = 19K, use 15k
 +
* Input resistance - parallel resistors R1, R2 paralleled with transistor input impedance
 +
** R1=15K, R2=3.3K
 +
** Transistor resistance = Beta AC (30) times re
 +
*** re = 26 / Ie (10 mA in mA) = 26/10 =
 +
*** Beta AC * re = 30*2.6 = 78 ohms - predominates
 +
** All in parallel are 75.8 ohms
  
−
* LTSPICE Simulation
+
=== Transformers ===
  
−
[[file:LTSPice_10dB.PNG]]
+
* T1 50:75.8 ohms
 +
** n = sqrt(Zout/Zin) = sqrt(75.8/50) = 1.23
 +
** 9:11 turns ratio
 +
* T2 - different than Charlie's design since my Crystal filters are all 50 ohms in/out
 +
** 250:50 ohms
 +
** n = sqrt(250/50) = 2.23:1
 +
** 11:5 turns
  
−
=== Attenuator Construction ===
+
=== Charlie's Notes ===
  
−
* Single side copper clad PCB
+
[[FILE:IF Amp_0046A.jpg]]
−
** 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]]
+
[[FILE:IF Amp_0046B.jpg]]
  
−
* Cut "T" Shaped pads
+
[[FILE:IF Amp_0046C.jpg]]
−
** I used nibbler
 
−
* Center fits between connector ground pins
 
−
* Glue down pads with Superglue
 
  
−
[[file:Atten_02_Pads_720px.jpg]]
+
[[FILE:IF Amp_0047A.jpg]]
  
−
* Solder center pin with big solder blob
+
[[FILE:IF Amp_0047B.jpg]]
−
** A bit too high for direct contact
 
−
* Verify raised pad does not short to ground
 
  
−
[[file:Atten_03_Solder CenterPads_720px.jpg]]
+
[[FILE:IF Amp_0047C.jpg]]
  
−
* Solder side resistor(s)
+
== Video ==
−
* Leave room for center resistor(s)
 
  
−
[[file:Atten_04_Solder Side_Resistors_720px.jpg]]
+
<video type="youtube">CHdtoupH2Vg</video>
  
−
* Measure side resistors from pad to ground
+
<video type="youtube">YJTsWV2kzFY</video>
−
* Should match value
 
−
* Solder center resistor(s)
 
  
−
[[file:Atten_05_Solder Center_Resistors_720px.jpg]]
+
<video type="youtube">xPFzFhM0ojE</video>
  
−
* Verify no shorts between centers and ground
+
== Assembly Sheet ==
  
−
== Attenuator Design - Rev 2 ==
+
* [[RF Amplifier Assembly Sheet]]
−
 
 
−
[[FILE:ATTEN.PNG]]
 
−
 
 
−
* SMA connectors
 
−
* Resistors
 
−
** 1206
 
−
*** 1/4W
 
−
** 1% values
 
−
 
 
−
[[file:10dB_Attenuator.PNG]]
 
−
 
 
−
=== Parts ===
 
−
 
 
−
{| class="wikitable"
 
−
! Mfr. #
 
−
! Manufacturer
 
−
! Customer #
 
−
! Qty
 
−
! R1/R2
 
−
! Description
 
−
|-
 
−
| RK73H2BTTE17R8F
 
−
| KOA Speer
 
−
| ATTEN_03DB
 
−
| 1
 
−
| R1
 
−
| Resistors - SMD 1/4W 17.8 ohms 1%
 
−
|-
 
−
| RC1206FR-07294RL
 
−
| YAGEO
 
−
| ATTEN_03DB
 
−
| 2
 
−
| R2
 
−
| Resistors - SMD 294 ohms 1/4W 1206 1%
 
−
|-
 
−
| RK73H2BTTD37R4F
 
−
| KOA Speer
 
−
| ATTEN_06DB
 
−
| 1
 
−
| R1
 
−
| Resistors - SMD 1/4W 37.4 ohms 1%
 
−
|-
 
−
| CRCW1206150RFKEAC
 
−
| Vishay
 
−
| ATTEN_06DB
 
−
| 2
 
−
| R2
 
−
| Resistors - SMD 1/4Watt 150 ohms 1%
 
−
|-
 
−
| RC1206FR-0771R5L
 
−
| YAGEO
 
−
| ATTEN_10DB
 
−
| 1
 
−
| R1
 
−
| Resistors - SMD 71.5 ohms 1/4W 1206 1%
 
−
|-
 
−
| RC1206FR-0797R6L
 
−
| YAGEO
 
−
| ATTEN_10DB
 
−
| 2
 
−
| R2
 
−
| Resistors - SMD 97.6 ohms 1/4W 1206 1%
 
−
|-
 
−
| RK73H2BTTD1070F
 
−
| KOA Speer
 
−
| ATTEN_13DB
 
−
| 1
 
−
| R1
 
−
| Resistors - SMD 1/4W 107 ohms 1%
 
−
|-
 
−
| RC1206FR-0778R7L
 
−
| YAGEO
 
−
| ATTEN_13DB
 
−
| 2
 
−
| R2
 
−
| Resistors - SMD 78.7 ohms 1/4W 1206 1%
 
−
|-
 
−
| AC1206FR-07249RL
 
−
| YAGEO
 
−
| ATTEN_20DB
 
−
| 1
 
−
| R1
 
−
| Resistors - SMD 249 ohms 1/4W 1206 1%
 
−
|-
 
−
| RK73H2BTTDD61R9F
 
−
| KOA Speer
 
−
| ATTEN_20DB
 
−
| 2
 
−
| R2
 
−
| Resistors - SMD 61.9 ohms 1%
 
−
|-
 
−
| RK73H2BTTD7870F
 
−
| KOA Speer
 
−
| ATTEN_30DB
 
−
| 1
 
−
| R1
 
−
| Resistors - SMD 1/4W 787 ohms 1%
 
−
|-
 
−
| AC1206FR-0753R6L
 
−
| YAGEO
 
−
| ATTEN_30DB
 
−
| 2
 
−
| R2
 
−
| Resistors - SMD 53.6 ohms 1/4W 1206 1%
 
−
|-
 
−
| RC1206FR-072K49L
 
−
| YAGEO
 
−
| ATTEN_40DB
 
−
| 1
 
−
| R1
 
−
| Resistors - SMD 2.49k ohms 1/4W 1206 1%
 
−
|-
 
−
| RK73H2BTTD51R0F
 
−
| KOA Speer
 
−
| ATTEN_40DB
 
−
| 2
 
−
| R2
 
−
| Resistors - SMD 1/4W 51 ohms 1%
 
−
|-
 
−
| RK73H2BTTDD49R9F
 
−
| KOA Speer
 
−
| ATTEN_50_60DB
 
−
| 2
 
−
| R2
 
−
| Resistors - SMD 49.9 ohms 1%
 
−
|-
 
−
| RC1206FR-077K87L
 
−
| YAGEO
 
−
| ATTEN_50DB
 
−
| 1
 
−
| R1
 
−
| Resistors - SMD 7.87k ohms 1/4W 1206 1%
 
−
|-
 
−
| RC1206FR-0726K1L
 
−
| YAGEO
 
−
| ATTEN_60DB
 
−
| 2
 
−
| R2
 
−
| Resistors - SMD 26.1k ohms 1/4W 1206 1%
 
−
|-
 
−
|}
 
−
 
 
−
=== Measurements ===
 
−
 
 
−
* NanoVNA
 
−
* S21 gain
 
−
* 1-900 MHz scan
 
−
* Calibrated with cable on thru
 
−
 
 
−
==== 40 dB ====
 
−
 
 
−
* Flat from 1-600 MHz
 
−
* Higher attenuation past 600 MHz
 
−
* -39.9 dB at 14 MHz
 
−
 
 
−
[[file:ATTEN1_NanoVNA_40dB.png]]
 
−
 
 
−
* Flat from 1-30 MHz
 
−
 
 
−
[[file:ATTEN1_NanoVNA_40dB_1-30MHz.png]]
 
−
 
 
−
== Attenuator Charts ==
 
−
 
 
−
[[file:dBm_vs_milliVolt_milliWatts.PNG]]
 
−
 
 
−
[[file:dBm_vs_Volta_Watts.PNG]]
 
−
 
 
−
[[file:dBm_vs_Volt_Watts.PNG]]
 
−
 
 
−
== References ==
 
−
 
 
−
* [http://leleivre.com/rf_pipad.html Attenuator Calculator] - Le Leivre.com
 
−
* [https://www.pasternack.com/t-calculator-pi-attn.aspx Attenuator Calculator] - Pasternak
 
−
 
 
−
* Heavily inspired by Alan (W2AEW) video
 
−
 
 
−
<video type="youtube">A5gGeV7CiQ0</video>
 
−
 
 
−
[[file:W2AEW_Attns-01.PNG]]
 
−
 
 
−
[[file:W2AEW_Attns-02.PNG]]
 
−
 
 
−
[[file:W2AEW_Attns-03.PNG]]
 

Revision as of 10:52, 6 November 2021

RF-Amp Front.png

RF Amplifier Features

RF Amplifier Design

Schematic

RF Amp Schematic-4.PNG

DC Operating Point

  • Ice = 10 mA
  • Ve = 0.1 * Vcc = 1.2V

Input/Output Transformer

FT37-43 Toroid

  • FT37-43
  • Wideband Transformers 5 - 400 MHz
  • Power Transformers 0.5 - 30 MHz
  • 10 turns = 35uH

FT37-43 10 Turns.PNG

Tracks

RF-Amp-tracks.PNG

Input Transformer

    • Input Transformer (T1 on Charlie's - T2 on this board)
      • 50:75.8 Ohms = 1 : 1.23 turns ratio
        • 9 turns primary, 11 turns on secondary

RF-Amp-T2.PNG

Output Transformer

    • Output transformer (T2 on Charlie's - T1 on this board)
      • 200:50 Ohms = 2:1 turns ratio
      • 10 turns primary (on transistor collector), 5 turns secondary (towards output)

RF-Amp-T1.PNG

LT Spice Simulation

Transformers

RF-AMP-LTSPICE XFMRS.PNG

Charlie Morris Design

Beta DC

  • Geometric mean min/max beta at operating current
    • =sqrt(100*300) = 173

Beta AC

  • Gain bandwidth product divided by operating frequency
    • Assume operating frequency of 10 MHz (my IF is actually at 9 MHz)
    • = 300/10 = 30

DC Operating Point

  • CE current 10 mA
    • V(emitter resistor) = 1/10 Vcc = 1.2V
      • R(emitter resistor) = 1.2V/0.01A = 120 ohms
  • VCE = 0.7V
  • V(emitter) = 1.2V
  • V(base) = V(emitter) + VCE = 1.9V
  • Assume current in biasing resistors = 10x current needed by DC beta
    • 10 mA in C-E, beta DC less = 10 mA/173 = 48 uA
    • 10x the current in the biasing resistors = 480 uA
  • R2 is 1.9V at 480 uA = 3.9K use 3.3K
  • R1 sources current to R2 and BE junction
    • Voltage = Vcc (12V) - 1.9V = 10.1V
    • Current = 480 uA + 48 uA = 528 uA
    • R1 = 10.1 / .528 mA = 19K, use 15k
  • Input resistance - parallel resistors R1, R2 paralleled with transistor input impedance
    • R1=15K, R2=3.3K
    • Transistor resistance = Beta AC (30) times re
      • re = 26 / Ie (10 mA in mA) = 26/10 =
      • Beta AC * re = 30*2.6 = 78 ohms - predominates
    • All in parallel are 75.8 ohms

Transformers

  • T1 50:75.8 ohms
    • n = sqrt(Zout/Zin) = sqrt(75.8/50) = 1.23
    • 9:11 turns ratio
  • T2 - different than Charlie's design since my Crystal filters are all 50 ohms in/out
    • 250:50 ohms
    • n = sqrt(250/50) = 2.23:1
    • 11:5 turns

Charlie's Notes

IF Amp 0046A.jpg

IF Amp 0046B.jpg

IF Amp 0046C.jpg

IF Amp 0047A.jpg

IF Amp 0047B.jpg

IF Amp 0047C.jpg

Video

Assembly Sheet

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