Difference between revisions of "SSB6 Design"

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[[file:SSB6_P1891_tEST_02_TRANSFORMER_TEST.JPG]]
 
[[file:SSB6_P1891_tEST_02_TRANSFORMER_TEST.JPG]]
 
* Add machine socket pins to install parts
 
 
[[FILE:SSB6_P1892-720px.jpg]]
 
  
 
* Measure transformer impedances from NanoVNA
 
* Measure transformer impedances from NanoVNA
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[[file:SSB6_NanoVNA_1-30MHz_Transformer_Input_Impedancee.png]]
 
[[file:SSB6_NanoVNA_1-30MHz_Transformer_Input_Impedancee.png]]
 +
 +
* Add machine socket pins to install parts
 +
 +
[[FILE:SSB6_P1892-720px.jpg]]
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* Install caps in socket pins
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<pre>
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08 8.997809 10.3 10.3
 +
30 8.997810 11.3 11.3
 +
48 8.997812 13.3 13.3
 +
50 8.997814 15.3 15.3
 +
31 8.997818 19.3 19.3
 +
46 8.997822 23.3 23.3
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</pre>
  
 
== References ==
 
== References ==

Revision as of 19:43, 29 October 2021

SSB6 P1889 Soldered-Grounded Cases 720PX.jpg

Design

  • 6 element filter
  • W7ZOI Crystal Filter paper has several crystal filter designs
    • Narrow bandwidth bandpass filters for CW/SSB
    • This is the 6 crystal SSB6
  • Used for transmit/receive
  • 9 MHz nominal frequency
  • 50 Ohms in/out impedance
  • Bin crystals using Colpitts Crystal Oscillator
    • Hand select close values from a pile of crystals
    • Can get much closer than 10% of bandwidth with 50 crystals
  • W7ZOI Filters on Kits and Parts Boards
    • Other filter builds
    • 5 or less crystals

W7ZOI SSB6 Schematic

XTAL-SSB-6Crystals.PNG

  • Response curve

W7ZOI SSB6 Curve.PNG

Build

FT37-43 10 turns 9MHz.PNG

Schematic

SSB6 SCHEMATIC.PNG

Dishal Values

  • Impedance = 195.9
RefDes Dishal  RefDes W7ZOI
Ck12   87.3    C3/C9  82
Ck23   110.9   C4/C8  100
Ck34   114.4   C6     100
Cs1    110     C2/C10 120
Cs3    369.5   C5/C7  470

Dishal-sim-01.PNG

Measured Crystal Values

  • 6 crystals within 7 Hz of each other
    • Selected from 50 purchased
Number Freq        Delta from average
09     8.997791    -7.7
12     8.997791    -7.7
41     8.997793    -5.7
06     8.997794    -4.7
21     8.997798    -0.7
38     8.997798    -0.7

Enclosure 80x50x20

  • Fits in 80x50 extruded enclosure
  • Material: Aluminum
  • Color: black
  • Size: approx.80*50*20mm
  • Thickness: approx.1mm

Enclosure-80x50x20.jpg

Performance Measurements

Overall

  • NanoVNA
  • 2.5 KHz / div

SSB6 NanoVNA 9MHz 2.5KHzPerDiv.png

Detailed

  • 1 KHz/div
  • Bandpass looks about 2500 KHz = good
    • Left freq = 8.99762 MHz
    • Right freq = 9.00005 MHz
    • Delta = 2.43 KHz
    • Center frequency = 8.99885 MHz
      • Implies crystals are properly matched?
  • Insertion loss at "best" point (red marker) -5.14 dB = OK
  • Deep skirts = good
  • Ripple looks bad
  • Right side low

SSB6 NanoVNA 9MHz 1KHzPerDiv.png

Compared to SSB4

  • Fcenter = 8.998MHz
  • Span = 10KHz
  • 1 KHz/div
  • Skirts much deeper on SSB6 than SSB4
    • -90 dB on SSB6 at window edges
    • -60 dB on SSB4 at window edges
  • Passband much flatter on SSB4
  • Insertion loss lower on SSB4
  • SSB4

SSB4 vsS SB6 NanoVNA 9MHz 1KHzPerDiv.png

Improvements

  • Investigate changes to remove ripple and clean up right side of passband

Clean Board

  • Cleaned board
  • Removed wires on transformer that were not clipped flush-ish
    • No effect - same ripple, same drop at the right side, same insertion loss
  • No change

SB6 NanoVNA 9MHz 1KHzPerDiv Added Grounds.png

Add grounds to cases of crystals

  • Had to scrape away solder mask to solder
    • Through hole vias were plated through
    • Would be better with ground pads with cleared solder mask and thermal relief (Version 2)
  • No change

SSB6 P1889 Soldered-Grounded Cases 720PX.jpg

Incremental Build and Test

  • Start with unpopulated board
  • Add SMA connectors

SSB6 P1887 Test 01 SMAs-Installed 720PX.jpg

  • Added transformers
  • Installed 200 ohm resistors at input caps to ground
    • At C1, C11

SSB6 P1891 tEST 02 TRANSFORMER TEST.JPG

  • Measure transformer impedances from NanoVNA
    • Input
      • 48.9-j0.900 Ohms
      • VSWR 1:1.031
    • Output
      • 48.7-j0.714 Ohms
      • VSWR 1:1.031
  • Impedance is flat over passband
  • Transformer working as expected

SSB6 NanoVNA 9MHz Transformer Input Impedance.png

  • 1-30 MHz scan
  • Toroid flat to board or tilted up = same performance
  • Not flat over band, but OK at 9 MHz

SSB6 NanoVNA 1-30MHz Transformer Input Impedancee.png

  • Add machine socket pins to install parts

SSB6 P1892-720px.jpg

  • Install caps in socket pins
08	8.997809	10.3	10.3	
30	8.997810	11.3	11.3	
48	8.997812	13.3	13.3	
50	8.997814	15.3	15.3	
31	8.997818	19.3	19.3	
46	8.997822	23.3	23.3

References

Sorted crystals table

Assembly Sheet