Well, but what can I do with old Ferrite "Bead" RF Chokes. I just cut of the chokes together with
wires from scrapped devices. To remove the ferrite tube from the
chokes takes time and tools. So I decided make some experimenters
with the chokes without disassembly those ones.
I find in my junk box four identical Ferrite "Bead"
RF Chokes. Each choke has length 36- mm with outer diameter 18-
mm. Two wires cable went through the choke. The wire was marked
as diameter 18- AWG and 300- V voltage. My idea was to create
a kind of RF transformer with the chokes.
First experimental transformer was made according Figure 4. It was classical RF Transformer
where one turn is primary and second turn is the secondary winding.
Then transformer was tested. Primary winding was connected to
MFJ- 259B. Secondary winding was loaded on to 51- Ohm resistor.
Figure 5 shows the transformer
loaded to 51-Ohm resistor. Table 1 shows data obtained for the one Ferrite
RF Choke. As you can see from the table the transformer may be
used for receiving purposes. I tested the transformer with my
transceiver IC- 718 and receiver Hallicrafters
S- 85. Transformer worked good up to 40- meter Band. Then I observed
some dropping of receiving signals. However I could compensate
it with adding RF- gain at transceiver and receiver where the
transformer successfully worked at MW-Band.
Conclusion: The transformer may be used as Insulated Transformer for Receiver at the
HF and MW.