It has been stated that winding two solenoids rf chokes end-to-end will in
effect make one rf choke, so that they must be at right angles.
That statement is only true if the rf chokes couple. But, it is possible
for them not to couple. How? Wind them in opposite directions. Then,
coupling will be minimal.
I just wound two solenoid rf chokes in line, separated by about 1/4".
Measured the resonance of the first rf choke before winding the second.
Then, wound the second with more turns, so I could look for a different
resonant frequency. The resonant frequency of the first was unaffected by
the additional solenoid wound end-to-end. Then checked the resonant
frequency of the second coil. It was right where it was supposed to be.
I then measured the inductance and they added.
So, it is possible to make rf chokes on one form for the purpose of avoiding
resonant frequencies.
The problem with resonant rf chokes is that the hi Q creates fireworks.
There may be another solution, and that is to use resistance wire for the rf
choke. It is common to install a glitch resistor in the high voltage line.
If you wind an rf choke with the correct resistance wire so that the desired
resistance is equalled by the wound rf choke, then you can eliminate the
resistor. Whether the choke Q would be low enough to not worry about
resonances I am not sure.
That is a project for another day, to wind such a choke and get the Q meter
out - but I do not have neough desk space to do that at the moment.
73, Colin K7FM
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