Re: Combination Polydoroff and contra wound FSL


Camille LeBlanc
 

Hello Everett,

Thanks for the reply. I intended to use my FSL for both MW and LW, so I was hoping for both maximum sensitivity and wide frequency range. I might try some winding experiments using regular 20 AWG twisted wire. Like you pointed out Litz wire is just too expensive to cut up for the sake of experimentation with unknown results. I also just noticed an error in my original posting. The 4PDT switch should have read DPDT. However if I go the 3 coil route then the DPDT is out. I will give this some consideration before any winding methods are attempted. Thanks again Everett.

73
Cam VE9CAM
--------------------------------------------

On Sat, 3/5/16, Everett Sharp everettsharp@... [ultralightdx] <ultralightdx@...> wrote:

Subject: Re: [ultralightdx] Combination Polydoroff and contra wound FSL
To: ultralightdx@...
Received: Saturday, March 5, 2016, 7:20 AM


 









Hi Cam,
I am not sure if you
are if you are wanting to operate on one band, or dual
bands? If you are just wanting one band, MW, then stick with
all 4 coils wound in the same direction for a Polydroff
configuration. The reason for winding in coils in contra is
to reduce interaction between the coils. With a 12"
wide FSL you should have enough spacing between the coils
that there should be no interaction issues. 
If on the other hand if
you are wanting to make a multi-band configuration, then you
need to use 3 coils, wound in Contra. 2, or 4 coils do not
work out well. The only way I was ever able to get 2 coils
to work out well for a dual band FSL was to have cut the
ferrite bars into segments, which you can see in my article
"Experiments with a 7 1/2" FSL.  
Also you did mention
what wire you will be using, if it is Litz wire you are
better off going with the tried and proven, rather then wast
good wire on trying something that may, or may not
work. 
Everett N4CY
On Mar 4,
2016, at 10:22 PM, Camille LeBlanc camudx@...
[ultralightdx] <ultralightdx@...>
wrote:
















 






Hello Gang,



I just finished all the pre-wiring stages of my new FSL. It
will give about a 7 inch diameter coil and comprises of 3
rows of 47 each 100 mm ferrite rods for a total of length of
300 mm (12 inches) using 141 rods. Now before winding any
wire on this thing, and reading all the articles in the
files section, I got to thinking if anyone has ever had the
idea of combining both winding methods into one design. I
was thinking of two possibilities.



Possibility 1:

Coil 1 and 3 wound in one direction then coil 2 and 4 wound
contra. Coil 1 and 3 connected in Polydoroff fashion along
with coil 2 and 4 also connected with the Polydoroff method.
Each Polydoroff pair could be regarded as a single coil and
brought out to a 4PDT switch to allow for series/parallel
band switching.



Possibility 2:

Coil 1 and 2 connected in Polydoroff, then coil 3 and 4 also
connected in Polydoroff but coils 3 and 4 wound contra to
coils 1 and 2. Again each pair could be regarded as one
single coil and also switched by a 4PDT switch for band
switching.



It would seem to me that this combining of both winding
methods would give the best of both worlds and provide all
the desired advantages of both methods. Maybe I'm
missing something here because sometimes I get crazy ideas.
Does anyone know if either scheme would work?



Regards

Cam
























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