Richard's Preselector Project
Home   Next Page
July 15, 2005. Richard Gagnon and I have been discussing some of the preselector designs I've been developing over the years. He decided to build the latest version of my circuit, incorporating some of his own clever innovations. This is a work-in-progress, so we'll add to it as the project progresses.--Bob Betts
Above: The front panel with artwork, knobs and controls (two different camera angles).
Above: Front panel artwork, positive and positive reversal.
Left and below: Inside views of the front panel and chassis before wiring.
NOTE: For a more detailed view, you may "right-click" an image to copy it to your clipboard and paste it into a picture viewer of your choice. Also, go to;[email protected]
Labeling Front Panel
The pattern was drawn for a 10" X 4" (254mm X 101.6mm) panel. I found this spec from the Digi-Key site when I ordered the enclosure but I found out the panel was slightly smaller so I had to change the printer settings. Using Photo Studio 5, I selected 10.28" and 4.18", plus allow distortion. I printed on a HP DeskJet 3322 with W98SE. Those of you who are graphics/printer smart will know why I used the indicated settings. All I know is the pattern fit just fine.
I opted to print on white ink jet paper, lightly sprayed both sides with a art fixative and let each side dry about 12 hours before spraying the other side and installing on the panel. This sealed the paper. I used Elmer's spray adhesive to apply the label sheet. I used a light spray on the steel panel and waited 15 minutes before applying the sheet, which I trimmed with a sharp Xacto knife before applying. I practiced this a few times without adhesive to make sure of alignment. I also practiced with a reverse print clear material. I made some slight measuring errors for some of the holes, which is why I did not just print to clear material. The paper covers up these errors. I let the spray adhesive set for 24 hours before applying a clear self adhesive-laminating sheet over the white sheet. The result is very nice. I decided to keep it simple. I have installed all the controls and the panel is quite sharp when mounted in the chassis with the knobs in place. I need one more knob, which I will order with parts for another project.
Preselector Parts
2 ea 1 uH air coil, #20 enamled wire
2 ea Mouser 580-22R103 10uh Q=140 R=0.05 ohm
2 ea Mouser 580-22R104 100uh Q=160 R=0.5 ohm
2 ea Mouser 580-22R105 1mh Q=150 R=3.8 oms
2 ea Mouser 434-02-103J 10mh Q=100 R=12.1 ohms
RF Transformers
Used 4: 1 to change 52 ohm impedance to 12 ohm impedance for higher Q.
Used 1:1 to dc isolate Notch tuning circuit.
Coil Craft
WB1010-PC       WB1010-SM  1:1   0.005 - 100  
WB1040-PC       WB1040-SM  4:1   0.2 - 300       
(Mini Circuits
1 ea T1-6   W38   10kc - 150 Mc      1:1    C    
3 ea T4-6   X65      .02 - 200 Mc      4:1    C    
1 ea "BB" Homebrew Splitter to connect two receivers to the preselector.
Variable Capacitors
2 ea Jackson Brothers Air Variable - 9-365pF
5 ea Mouser 450-1171
Vernier Dial
1 ea Ocean State Electronics VD112-10   1-1/2"   0-10
1 ea VD112-10  0-10 vernier dial on hand
1 ea Hammond,  Digi-Key HM345-ND  Useable space, 9.8750 X 6.625 X 3.8750   (250.825mm X 168.275mm X  98.4250mm)
Advertised space is: 10" x 8" x 4" (254mm x 203.2mm x 101.6mm)
3 ea miniature SPST On/Off
1 ea SPDT On/Off/On
1 ea Rotary switch 3 pole 4 pos 10YX034 2 poles/3 pos used
2 ea Rotary switch 1 pole, 12 pos, on hand,  5 pos used
Active Devices
1 ea green LED preamp power indicator
1 ea Mini-Circuits MAR-6 Monolithic amplifier, or
1 ea Ransey SA7 wideband amp.
1 ea 78L05 for MAR-6
1 ea 78L12 for SA7
2 ea Mouser 17 mm, carbon, 5K pots 31CN305
5 ea Chassis BNC
1 ea Power connector
Power Supply
1 ea CSI1862, 13.8V 6A  for powering:
Betts Preselector
Icom R75
Palstar R30C
MFJ1024 Active antenna
Amrad LF/MW/HF Active antenna
Hosted by