Print this page, and also see "Setup".
Construction details and the adjustment of the ferrite antenna are HERE.
L102 : two wires
twisted, 7 turns, 1mm dia on a Conrad 8x50mm Ui=300 ferrite rod.
Use one pair twisted wires from a CAT5 network cable.
Nominal self inductance : 8.0 uH. See "Setup" for one time adjustment of the self inductance.
L101 : 3 turns over the center of the ferrite rod.
Local oscillator coil L2 :
Standard Neosid 7.5 x 7.5mm RM2.25 BV5048 .
One time adjustment of L2 :
Connect a capacitor of 150 pF 1% with abt. 2cm long legs to pins 1 and 5.
Hold a grid dip meter near/between the capacitor wires.
Find the circuit resonance.
Adjust the ferrite core WITH A SPECIAL WELL FITTING TOOL for 13.0 MHz resonance.
Fill the hole of the coil with pure bee wax.
Remove the capacitor.
From now on, L2 should NOT be readjusted. Tuning the oscillator should only be done by C110.
10,7 MHz IF coils.
L3,6 : 7.5 x 7.5mm RM2.25, Standard Neosid coil BVW5170.
REM : In 2014 a coil type BVW5056
was used. In 2017 it is not available anymore. Now a BVW5170
type coil is used .
But coil BVW5170 has a different connected coil : diagonally.
For correct coil connections, you first have to make following modification :
PCB #15 the coil connections of a modified coil BVW5170 should be at the
bottom left and top right ==>>
See the bottom copper side of the PCB.
1. With a felt pen, make
marks on the bottom of the coil form near the pins connected to the
CHECK that no short circuits are present, especially near the soldered ground lugs.
REM: the here used Neosid SD75 type chokes have a higher self inductance at a given Self Resonating Frequency than smaller chokes on ferrite rods.
L7,10,12 - 22uH: standard Neosid radial
choke SD75 RM5
(SRF >= 11MHz). Conrad orderNr 535389
Or use vertically placed 7x3mm axial chokes 10uH.
L11 - 68uH : Neosid radial
chekel SD75 RM5
(SRF ca. 10MHz). Conrad
Or use vertically placed 7x3mm axial chokes 22 uH.
L13,14,15,201 : 10uH axial chokes Epcos 7x3mm. Conrad orderNr 501881
Order at www.box73.de : "Ferrit-Dämpfungsperlen". Small ferrite pearl 4x3mm.
10.7 MHz crystalfilter F1+2: Order at www.box73.de : "quartz filter" 10M12B.
BFO crystal Cr:
Order at www.box73.de : "quartz 10.7MHz HC18U
In order to improve frequency stability, and to prevent 10.7 MHz RF radiation, you should solder the can if the crystal QUIKLY to a special grounding surface near the crystal.