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...in the middle of shield.
Regards
Joze
----- Original Message -----
Sent: Tuesday, September 27, 2011 8:24
PM
Subject: Re: LF: Re: My first ferrite
experiments
Hi Joze,
looks like in your antenna
the coil is wound over the shield, am I
correct?
Regards
Daniele
Da: Joze
Konda - S52AB <[email protected]>
A: [email protected]
Inviato: Martedì 27 Settembre 2011
19:42
Oggetto: Re: LF: Re: My
first ferrite experiments
HI Daniele
This is my great ferrite rood RX antenna with
aluminium shield:
Good worked.
Regards
73, Joze s52ab
----- Original Message -----
Sent: Tuesday, September 27, 2011 5:15
PM
Subject: Re: LF: Re: My first ferrite
experiments
Hello Stefan,
> but maybe the Q is
reduced by the aluminium shield!
Do you think the
aluminium could be the problem or the distance between the coil and the
core? I could replace the aluminium tube with a plastic tube, if shielding
is not necessary, but this would not improve the Q if the problem is the gap
between the coil and the core.
> Are the rods
galvanically separated from each other by a thin plastic tape? What type is
the ferrite material?
Yes I put two
layers of plastic tape on tips of each rod. The ferrite material is russian
MU400HH.
Best regards
Daniele
Da: Stefan Schäfer
<[email protected]>
A:
[email protected]
Inviato: Martedì 27 Settembre 2011
13:48
Oggetto: Re: LF: Re:
My first ferrite experiments
Hello Daniele, Nice work and good
equipment. I would suggest to make the wires between coil and cap as
short as possible and not to use these crocodile clamps. HF litz wire should
help about the Q but maybe the Q is reduced by the aluminium shield! Are the
rods galvanically separated from each other by a thin plastic tape? What
type is the ferrite material? 73, Stefan/DK7FC PS: Tell me if
you need a test signal ;-) Am 27.09.2011 12:33, schrieb Daniele
Tincani:
Pics 3 and 4 are attached here.
Da:
Daniele Tincani <[email protected]>
A: "[email protected]"
<[email protected]>
Inviato: Martedì 27 Settembre 2011
12:31
Oggetto: My first
ferrite experiments
Hello LF,
this evening I had some free time to spend for starting my very
simple tests with ferrite rods. Picture 1 in the attached zip file shows
one of the rods (about 10mm diameter x 200mm long) together with a short
piece of plastic tube that I have used to adapt the rods to a
larger-diameter slotted aluminium tube - shown in picture 2. As you
can see, the longitudinal cut on the tube is not really regular and
"clean". I'm not very good at working with metals. Nevertheless, I hope it
will do the job, that is acting as a shield between the rods and the coil.
Picture 3 shows two of the three rods I used, each inserted in a
short piece of plastic pipe and protected with heat shrink tube and some
masking tape.
Finally, picture 4 shows the very provisional setup that I
used to try measuring Q of an LC pair composed by a 2-gangs variable
capacitor plus a 55-turns coil wound over the aluminium tube containing
the ferrite rods. I performed several measures, with 1, 2 or 3 rods inside
the tube. I saw that using 3 rods increases the inductance significantly.
For example, at an intermediate position of the varcap, resonance was
at 1037KHz with only 1 rod inside the tube, but it was at 767 KHz with 3
rods.The Q value also increases slightly using 3 rods, even thought
in my tests I got only a miserable figure of about 30. Anyway,
I decided to go with 3 rods for my next step, that will be to try Litz wire for the coil and see
what happens.
Note: pics 3 and 4 will be
attached to a re-sent of this message.
Regards
D.
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