Ferrite Magnet antenna ; parts purchase / design question
 

All:
Working on a ferrite antenna.

Ordered parts from Ocean state electronics, ( via website)

( http://www.oselectronics.com )

bought their 14-365 Pf variable capacitor and two ferrites:
one
FR4-33 #33 1/2" Diameter X 4" Long

and then

FERRITE "LOOP STIK" ANTENNA
band, 540KHz - 1600KHz. Measures 5/16" Dia. x 3 1/2" Long. Includes mounting
bracket and wiring diagram. Q=25, L=788µH.
LA-540...................

- Now, follow this :

I figure I'll use the 8 inch loopstick for the ' Primary" antenna. setting it
in a window..

Hook the " primary " up to the variable capacitor via about 10 feet of co-ax
wire.
- so I can Tune it from 10 + feet away.

THEN use the "FERRITE "LOOP STIK" ANTENNA"( part LA-540.)
as a " transmitter"
setting it on top of my sangean 606A;

- So the primary can be tuned from far away,
still usable via the capacitor and 10 + feet of wire..

- Any thoughts on this ? Sheer folley? Intellectual Property Theft? Genius ??

Happy as a Clam At High Tide..

Dan

"Diverd4777" wrote in message
...
All:
Working on a ferrite antenna.

Ordered parts from Ocean state electronics, ( via website)

( http://www.oselectronics.com )

bought their 14-365 Pf variable capacitor and two ferrites:
one
FR4-33 #33 1/2" Diameter X 4" Long

and then

FERRITE "LOOP STIK" ANTENNA
band, 540KHz - 1600KHz. Measures 5/16" Dia. x 3 1/2" Long. Includes
mounting
bracket and wiring diagram. Q=25, L=788µH.
LA-540...................

- Now, follow this :

I figure I'll use the 8 inch loopstick for the ' Primary" antenna.
setting it
in a window..

Hook the " primary " up to the variable capacitor via about 10 feet of
co-ax
wire.
- so I can Tune it from 10 + feet away.

THEN use the "FERRITE "LOOP STIK" ANTENNA"( part LA-540.)
as a " transmitter"
setting it on top of my sangean 606A;

- So the primary can be tuned from far away,
still usable via the capacitor and 10 + feet of wire..

- Any thoughts on this ? Sheer folley? Intellectual Property Theft?
Genius ??

Happy as a Clam At High Tide..

Dan




One problem might come from the capacitance of the coax connected to the
tuning cap. It will restrict the tuning range. The extra capacitance
will have the same effect as not being able to open the cap all the way.
Otherwise, it should work. The tuning range problem will be lessened if
you connect the coax to a few turns of wire wrapped by the ground side
of the coil and use a similar coil on the other ferrite rod.

Frank Dresser

That peice of coax will introduce lots of aditional capacitance and
inductance. Have fun getting it to work.


"Diverd4777" wrote in message
...
All:
Working on a ferrite antenna.

Ordered parts from Ocean state electronics, ( via website)

( http://www.oselectronics.com )

bought their 14-365 Pf variable capacitor and two ferrites:
one
FR4-33 #33 1/2" Diameter X 4" Long

and then

FERRITE "LOOP STIK" ANTENNA
band, 540KHz - 1600KHz. Measures 5/16" Dia. x 3 1/2" Long. Includes
mounting
bracket and wiring diagram. Q=25, L=788µH.
LA-540...................

- Now, follow this :

I figure I'll use the 8 inch loopstick for the ' Primary" antenna. setting
it
in a window..

Hook the " primary " up to the variable capacitor via about 10 feet of
co-ax
wire.
- so I can Tune it from 10 + feet away.

THEN use the "FERRITE "LOOP STIK" ANTENNA"( part LA-540.)
as a " transmitter"
setting it on top of my sangean 606A;

- So the primary can be tuned from far away,
still usable via the capacitor and 10 + feet of wire..

- Any thoughts on this ? Sheer folley? Intellectual Property Theft? Genius
??

Happy as a Clam At High Tide..

Dan

Thanks Frank..

- Guess I'll get the main ferrite loop to work first, then try the long leads &
the coils.
retuning it with 1, 2,4 then 8 foot lengths to see what obtains..

I guess Very Very thin copper wire would introduce the least capacitance ??

Dan

In article , "Frank
Dresser" writes:


"Diverd4777" wrote in message
...
All:
Working on a ferrite antenna.

Ordered parts from Ocean state electronics, ( via website)

( http://www.oselectronics.com )

bought their 14-365 Pf variable capacitor and two ferrites:
one
FR4-33 #33 1/2" Diameter X 4" Long

and then

FERRITE "LOOP STIK" ANTENNA
band, 540KHz - 1600KHz. Measures 5/16" Dia. x 3 1/2" Long. Includes
mounting
bracket and wiring diagram. Q=25, L=788µH.
LA-540...................

- Now, follow this :

I figure I'll use the 8 inch loopstick for the ' Primary" antenna.
setting it
in a window..

Hook the " primary " up to the variable capacitor via about 10 feet of
co-ax
wire.
- so I can Tune it from 10 + feet away.

THEN use the "FERRITE "LOOP STIK" ANTENNA"( part LA-540.)
as a " transmitter"
setting it on top of my sangean 606A;

- So the primary can be tuned from far away,
still usable via the capacitor and 10 + feet of wire..

- Any thoughts on this ? Sheer folley? Intellectual Property Theft?
Genius ??

Happy as a Clam At High Tide..

Dan




One problem might come from the capacitance of the coax connected to the
tuning cap. It will restrict the tuning range. The extra capacitance
will have the same effect as not being able to open the cap all the way.
Otherwise, it should work. The tuning range problem will be lessened if
you connect the coax to a few turns of wire wrapped by the ground side
of the coil and use a similar coil on the other ferrite rod.

Frank Dresser

"Diverd4777" wrote in message
...
Thanks Frank..

- Guess I'll get the main ferrite loop to work first, then try the long
leads &
the coils.
retuning it with 1, 2,4 then 8 foot lengths to see what obtains..

I guess Very Very thin copper wire would introduce the least capacitance
??

Dan


Actually, if you don't want/need/HAVE to use coax, your route of least
capacitance would be standard television twinlead. The good foam surround
stuff has virtually no capacitance, and certainly would not have enough to
worry about at 10'.

"Diverd4777" wrote in message
...
Thanks Frank..

- Guess I'll get the main ferrite loop to work first, then try the
long leads &
the coils.
retuning it with 1, 2,4 then 8 foot lengths to see what obtains..

I guess Very Very thin copper wire would introduce the least
capacitance ??

Dan


Thin wire would introduce the least capacitance, but there won't be much
difference with reasonably spaced turns. The capacitance goes down
quickly with spacing, and there's really not much spacing difference
between very fine and fine wire if you wind maybe 12 turns per inch or
so. That's not a magic number or anything, just wind, test and adjust.

Frank Dresser

Another thing you might want to consider is the inductance of the loopstick.
For a 14-365pF tuning cap, you need right around 260uH for the loopstick. A
Q of at least 200 is desirable, for sharp tuning.

Pete

Frank Dresser wrote in message
...

"Diverd4777" wrote in message
...
All:
Working on a ferrite antenna.

Ordered parts from Ocean state electronics, ( via website)

( http://www.oselectronics.com )

bought their 14-365 Pf variable capacitor and two ferrites:
one
FR4-33 #33 1/2" Diameter X 4" Long

and then

FERRITE "LOOP STIK" ANTENNA
band, 540KHz - 1600KHz. Measures 5/16" Dia. x 3 1/2" Long. Includes
mounting
bracket and wiring diagram. Q=25, L=788µH.
LA-540...................

- Now, follow this :

I figure I'll use the 8 inch loopstick for the ' Primary" antenna.
setting it
in a window..

Hook the " primary " up to the variable capacitor via about 10 feet of
co-ax
wire.
- so I can Tune it from 10 + feet away.

THEN use the "FERRITE "LOOP STIK" ANTENNA"( part LA-540.)
as a " transmitter"
setting it on top of my sangean 606A;

- So the primary can be tuned from far away,
still usable via the capacitor and 10 + feet of wire..

- Any thoughts on this ? Sheer folley? Intellectual Property Theft?
Genius ??

Happy as a Clam At High Tide..

Dan




One problem might come from the capacitance of the coax connected to the
tuning cap. It will restrict the tuning range. The extra capacitance
will have the same effect as not being able to open the cap all the way.
Otherwise, it should work. The tuning range problem will be lessened if
you connect the coax to a few turns of wire wrapped by the ground side
of the coil and use a similar coil on the other ferrite rod.

Frank Dresser

"Diverd4777" wrote in message
...
Thanks Brenda:

I'll try the standard television Twinlead.

I really don't know anything much about electronics;
or reading scematics or soldering.

Maybe I should learn; from what I hear it's becoming a lost art!

Dan


Here's some fascinating stuff, if you're fascinated by such stuff:

http://www.du.edu/~jcalvert/tech/techhom.htm#elec

And, more to the point:

http://www.du.edu/~etuttle/electron/elecindx.htm

Any website author who writes "There is a very large number of texts on
electronic circuits, most of which are too big and rather bad." is OK
with me. He lists several books he's found helpful. Among them is the
Radio Amateur's Handbook. I also think they are excellent.

Frank Dresser

Diverd4777 wrote:

All:
Working on a ferrite antenna.

Ordered parts from Ocean state electronics, ( via website)

( http://www.oselectronics.com )

bought their 14-365 Pf variable capacitor and two ferrites:
one
FR4-33 #33 1/2" Diameter X 4" Long

and then

FERRITE "LOOP STIK" ANTENNA
band, 540KHz - 1600KHz. Measures 5/16" Dia. x 3 1/2" Long. Includes mounting
bracket and wiring diagram. Q=25, L=788µH.
LA-540...................

- Now, follow this :

I figure I'll use the 8 inch loopstick for the ' Primary" antenna. setting it
in a window..

Hook the " primary " up to the variable capacitor via about 10 feet of co-ax
wire.
- so I can Tune it from 10 + feet away.

THEN use the "FERRITE "LOOP STIK" ANTENNA"( part LA-540.)
as a " transmitter"
setting it on top of my sangean 606A;

- So the primary can be tuned from far away,
still usable via the capacitor and 10 + feet of wire..

- Any thoughts on this ? Sheer folley? Intellectual Property Theft? Genius ??

Happy as a Clam At High Tide..

Dan

Sounds like a great project! Like anything where there are
unknowns, experimentation is the fun way to go, so don't
hesitate to try different things.

The second, smaller ferrite to couple the signal into your
receiver is presumably in parallel with the 8" loopstick.
It's just that a bunch of coaxial cable is in-between.
Inductors in parallel have less inductance than either of
the two inductors, so this will throw you off using
equations built to serve the case of one loopstick and one
variable capacitor. This might cause you to need more
capacitance, which fortunately is easy to do by adding a
series of small caps in parallel until you achieve the
desired tuning range.

Someone else mentioned the extra capacitance added by the
coax. I'd *think* (I may well be all wet) that this extra
capacitance is a good thing given the partial loss in
inductance.

"Ross Archer" wrote in message
...

Sounds like a great project! Like anything where there are
unknowns, experimentation is the fun way to go, so don't
hesitate to try different things.

The second, smaller ferrite to couple the signal into your
receiver is presumably in parallel with the 8" loopstick.
It's just that a bunch of coaxial cable is in-between.
Inductors in parallel have less inductance than either of
the two inductors, so this will throw you off using
equations built to serve the case of one loopstick and one
variable capacitor. This might cause you to need more
capacitance, which fortunately is easy to do by adding a
series of small caps in parallel until you achieve the
desired tuning range.

Someone else mentioned the extra capacitance added by the
coax. I'd *think* (I may well be all wet) that this extra
capacitance is a good thing given the partial loss in
inductance.


The extra capacitance will cause a problem with the tuning range by
reducing the difference in the capacitance ratio of the tuning
capacitor. A 10 to 360 pf tuning cap will tune about a 4 to 1 ratio
with a normal fixed inductance with a typical amount of distributed
capacitance. Putting another 100 pf or more of capacitance in parallel
would reduce the tuning range to less than 3 to 1, which is less than
range of the AM broadcast band. Anyway, that's my instinct on this one.
There's a square law relationship between the tuning ratio and the
capacitance ratio but I really don't want to run the numbers.

I suggested using a link of a few turns to connect the coax rather than
putting the coax directly across the tuning cap in order to reduce the
added capacitance. That sort of hookup would probably also reduce the
energy transfer, but that gets into all that Nikola Tesla stuff, and I
really, really don't want to run those numbers.

Frank Dresser