ON1DHT's 50 MHz converter
50 MHz converter technical specifications
IC1 = NE602 or SA602
IC2 = 78L06
T1 = BC547
C1, C4 = 10uF/25v
C2, C3 = 100nF
C5 = 47uF/16v (tantaal)
C6, C15 = 47nF (polyester)
C7 = 47pF
C8 = 22pF
C9 = 0...22pF (green)
C10 = 2n2
C12 = 0...40pF (white)
C13 = 47pF
C14 = 39pF
C16,C17 = 330pF
C18 = 100pF
C19 = 22nF
C20, C21 = 470pF
P1 = 100 Ohm
R1 = 1k
R2 = 2k2
R3 = 100 Ohm
R4 = 5k6
R5 = 1k
P1 = 100 Ohm
L1 = 7 wnd 1mm silver 9mm coildiameter (drill 7), tap on 1,5 wnd from the cold end.
L2 = 11 wnd 0,6mm email 5mm coildiameter (drill 4)
L3, L4 = shokes (RFC) 10uH
Tune to the desired bandpass frequency (50Mc) with C9 until you have the best reception.
Use C12 to calibrate the output frequency to your receiver. The output frequency can be adjusted up to 300Hz.
The output HF-level can be adjusted with P1. Regulate it according to the sensitivity of your receiver.
Other output frequencies can be set by changing the 22MHz Xtal: Example:
output frequency is 26 MHz then you use a 24 MHz Xtal (50MHz - 24MHz =
Build the converter in a metal box and use small connections between the parts.
Important: use only a antenna designed for 50MHz! A simple dipole of around 3 meters in length (two times 1,45 meters) will work just fine if the propagation is there. Look at my homebrew site for a 3-element beam that works much better then a dipole and gives more gain, or a my 5/8 lambda vertical.
More info about the 50MHz band (6 meters, the Magic band...) can be found at my site at MagicBand or Radioamateur Info.
A PCB has been designed for this project by ON1MFW. E-mail me for detailed PCB. PCB-parts side PCB layout
Detailed information and manual (in Flemish (Nederlands)) ON1DHT's 50MC CONCVERTER MANUAL
This project has been published in CQ-QSO (in Dutch and French)
the ham-radio magazine of the UBA.
Magzine 06-07/2000 pages 14,15,16 and 17.
My E-mail address
Note: if you want to commercialise, publish or
distribute this project
then you need to ask permission to do so.
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