Date   
Re: Bitx Ver.1 Original -40 m???

John Backo
 

--- In BITX20@..., Arv Evans <arvid.evans@...> wrote:

John

Can those green VLF cores from CFL lamps be used to make RFCs for use at
HF frequencies?

Arv
_._

I doubt it. That thing is designed to operate at about 150-200 KHz. Try putting a SW receiver next to one and see what you get.

I just put a receiver next to one (23W) and got responses at 180 KHz, 270 KHz and 360 KHz plus a lot of RF noise around 400 KHz.

The circuit is nothing more than a simple flyback switching power supply, similar to but much less sophisticated than that in computer power supplies. They have a transistor oscillator, a transformer, a boost coil, and a fast diode to provide a surge voltage through a coil to bring it up to speed. The "CFL" is really just a fluorescent tube and operates like any of its much larger brethren in the kitchen.

I would doubt that they have more than .5cc of mercury in them though. That is not enough to do any serious harm, but mercury accumulates in the body and getting any in your system is not a good idea. It causes effects like muscular dystrophy. (this coming from one who played recklessly with it as a child and a chemistry major. HI HI)

That green core probably saturates at about 1 MHz.

The most interesting thing in there is the fast schottky diode. In the larger power supplies there are dual diodes and I have wondered how those "hot carrier" diodes would work as varactors.


john
AD5YE

Re: Bitx Ver.1 Original -40 m???

Mark <huitmarmottes@...>
 

How about green hi hi!

That's what just came out of the cfl I dissected. Anyways, too bad for the low frequency ones.

I wouldn't think UHF/VHF ones would be bad for HF...somewhere between air and and hf ferro core no? They are worried about saturation and hysteresis losses so those would be even less at hf, just probably the permeability would be lower so it may take a few more windings?

Cell phone ones -- ugh way too small I would think!

Litz wire is pretty expensive for a scavenging ham :-p Maybe you can get an xyl to weave you some -- good luck hey?

Cheers,

Mark.

--- In BITX20@..., "iam74@..." <iam74@...> wrote:



--- In BITX20@..., "Mark" <huitmarmottes@> wrote:

Hi :-)

I like the pvc pipe ideas for air core toroids. I don't know the size of tap washers originally used, but with the pipe you can get a nice large diameter and thickness so your air-inductor will require a lot less turns.

The advantage of the fewer turns needed for ferro-core inductors do count. With the finer wire and multiple turns needed to attain the inductance required for HF frequencies can lower the Q through skin and proximity effects.

To me, it's kind of a continuum for the cores. AT UHF/VHF you need lower inductance and ferro cores can become more easily saturated and experience increasing hysteresis losses, so air cores rule. At HF, ferro cores do have their advantages as the losses are linear with frequency so much less, and the relatively much fewer turns can result in higher Q through lower skin and proximity effect losses.

If you have space, you can put in some of those litz wire spider wound creations they use in crystal radios hi hi. But if going air-core toroidal, I think the pvc pipe (or large wood or plastic bead) forms John and Arv mentioned are the way to go.


Using Litz wire is a very good way to increase the inductance without unduely raising capacitance effects.

[john]



Since scavenged ferro-cores are free and getting more plentiful now (better than ending up in a landfill!) though I think they are good to try too.

Cheers,

Mark.
Yes, but unfortunately, the toroids used in CFL and switching power supplies are designed to be efficient at VLF, 15 KHz to about 150 KHz. They do not respond well at HF above 160m or so. The ones from televisions and cell phones are designed to work at UHF or flyback frequencies, also not so very good for HF. The best materials for powdered iron are #2, #6, and #7, which are red, yellow and tan color-coded. The next best are #15 (black) and #43 and #61 for ferrites.

The ferrites are not color-coded, so one never knows what one has without measuring it.

The yellow/white and grey ones are definitely for VLF use.


john
AD5YE

Re: Bitx Ver.1 Original -40 m???

Arv Evans
 

John

Can those green VLF cores from CFL lamps be used to make RFCs for use at
HF frequencies?

Arv
_._

On 01/25/2011 12:20 AM, iam74@... wrote:



--- In BITX20@... <mailto:BITX20%40yahoogroups.com>,
"Mark" <huitmarmottes@...> wrote:

Hi :-)

I like the pvc pipe ideas for air core toroids. I don't know the
size of tap washers originally used, but with the pipe you can get a
nice large diameter and thickness so your air-inductor will require a
lot less turns.

The advantage of the fewer turns needed for ferro-core inductors do
count. With the finer wire and multiple turns needed to attain the
inductance required for HF frequencies can lower the Q through skin
and proximity effects.

To me, it's kind of a continuum for the cores. AT UHF/VHF you need
lower inductance and ferro cores can become more easily saturated and
experience increasing hysteresis losses, so air cores rule. At HF,
ferro cores do have their advantages as the losses are linear with
frequency so much less, and the relatively much fewer turns can result
in higher Q through lower skin and proximity effect losses.

If you have space, you can put in some of those litz wire spider
wound creations they use in crystal radios hi hi. But if going
air-core toroidal, I think the pvc pipe (or large wood or plastic
bead) forms John and Arv mentioned are the way to go.

Using Litz wire is a very good way to increase the inductance without
unduely raising capacitance effects.

[john]



Since scavenged ferro-cores are free and getting more plentiful now
(better than ending up in a landfill!) though I think they are good to
try too.

Cheers,

Mark.
Yes, but unfortunately, the toroids used in CFL and switching power
supplies are designed to be efficient at VLF, 15 KHz to about 150 KHz.
They do not respond well at HF above 160m or so. The ones from
televisions and cell phones are designed to work at UHF or flyback
frequencies, also not so very good for HF. The best materials for
powdered iron are #2, #6, and #7, which are red, yellow and tan
color-coded. The next best are #15 (black) and #43 and #61 for ferrites.

The ferrites are not color-coded, so one never knows what one has
without measuring it.

The yellow/white and grey ones are definitely for VLF use.

john
AD5YE

Re: Bitx Ver.1 Original -40 m???

Arv Evans
 

John

I was thinking more of increasing L (decreasing turns requirement) by
increasing
mutual inductance with 360 degrees or more of core coverage. You do
bring up
an interesting point about the inductance clumping effect.

Arv
_._

On 01/24/2011 11:53 PM, iam74@... wrote:



--- In BITX20@... <mailto:BITX20%40yahoogroups.com>, Arv
Evans <arvid.evans@...> wrote:

John

You have got the idea! Way back in the early days of BITX20 we were
playing with
PVC tubing with slots for quickly winding the turns. Now the math and
procedures
seem to be catching up with the mechanics to make this into an
interesting field of
play. It all started to come together for me when I realized that I
could calculate
an A_L value for air-core toroids, and from that calculate the
number of
turns for
any inductance that was wound with that particular core dimension. I
wrote a
small Linux Shell-script program to do the math and it all seems to
make
perfect
sense. :-)

Next step is to devise a way to use any non-magnetic core's
cross-sectional area to
predict the A_L for any inductor that is wound on it. Also have to take
into consideration
the dielectric constant of the core material, but to-date that seems to
play a relatively
minor role in actual inductance values.

One benefit of magnetic cores though is an apparently tighter coupling
of mutual
inductance from the wrapped-around coil meeting it's opposite end.
Maybe one
could tighten up the magnetic coupling even more in air-core inductors
by making
the windings come all the way around, and possibly even over-wrap the
head and tail
by a few turns...?

Arv
_._

Yes, but all that would do is increase the Q a bit, and you could
cause some sort of buck-boost effect that would encourage a secondary
resonance by overlapping turns. Look at the problems power
transformers have with improper winding. And they laminate cores for a
reason.

If one calculates the A_L of any medium, what has one really done?
They have discovered the magnetic susceptance of that particular
medium. Faraday worked that out long ago, I think.

But the radio engineers learned early on that overlapping ends of a
coil produce strange effects sometimes, as did inserting a "foreign"
medium into it. It was decided that the more uniform the coil, the
better the actual result. So it is better to not complicate things too
much. The use of iron cores and ferrites was to reduce the size of the
device (apparently always a good thing). :) But that introduced all
kinds of secondary effects up to and including saturation. Oh, well...

But there is no reason that one could not work out a more-or-less
standard way of calculating inductance with any medium. One just has
to be aware that it changes with the change in the actual magnetic
field. If the field change is uniform, so is A_L. If not, well...

Anyway, I like it! Keep it up.

john
AD5YE

Re: Bitx Ver.1 Original -40 m???

John Backo
 

--- In BITX20@..., "Mark" <huitmarmottes@...> wrote:

Hi :-)

I like the pvc pipe ideas for air core toroids. I don't know the size of tap washers originally used, but with the pipe you can get a nice large diameter and thickness so your air-inductor will require a lot less turns.

The advantage of the fewer turns needed for ferro-core inductors do count. With the finer wire and multiple turns needed to attain the inductance required for HF frequencies can lower the Q through skin and proximity effects.

To me, it's kind of a continuum for the cores. AT UHF/VHF you need lower inductance and ferro cores can become more easily saturated and experience increasing hysteresis losses, so air cores rule. At HF, ferro cores do have their advantages as the losses are linear with frequency so much less, and the relatively much fewer turns can result in higher Q through lower skin and proximity effect losses.

If you have space, you can put in some of those litz wire spider wound creations they use in crystal radios hi hi. But if going air-core toroidal, I think the pvc pipe (or large wood or plastic bead) forms John and Arv mentioned are the way to go.


Using Litz wire is a very good way to increase the inductance without unduely raising capacitance effects.

[john]



Since scavenged ferro-cores are free and getting more plentiful now (better than ending up in a landfill!) though I think they are good to try too.

Cheers,

Mark.
Yes, but unfortunately, the toroids used in CFL and switching power supplies are designed to be efficient at VLF, 15 KHz to about 150 KHz. They do not respond well at HF above 160m or so. The ones from televisions and cell phones are designed to work at UHF or flyback frequencies, also not so very good for HF. The best materials for powdered iron are #2, #6, and #7, which are red, yellow and tan color-coded. The next best are #15 (black) and #43 and #61 for ferrites.

The ferrites are not color-coded, so one never knows what one has without measuring it.

The yellow/white and grey ones are definitely for VLF use.


john
AD5YE

Re: Bitx Ver.1 Original -40 m???

John Backo
 

--- In BITX20@..., Arv Evans <arvid.evans@...> wrote:

John

You have got the idea! Way back in the early days of BITX20 we were
playing with
PVC tubing with slots for quickly winding the turns. Now the math and
procedures
seem to be catching up with the mechanics to make this into an
interesting field of
play. It all started to come together for me when I realized that I
could calculate
an A_L value for air-core toroids, and from that calculate the number of
turns for
any inductance that was wound with that particular core dimension. I
wrote a
small Linux Shell-script program to do the math and it all seems to make
perfect
sense. :-)

Next step is to devise a way to use any non-magnetic core's
cross-sectional area to
predict the A_L for any inductor that is wound on it. Also have to take
into consideration
the dielectric constant of the core material, but to-date that seems to
play a relatively
minor role in actual inductance values.

One benefit of magnetic cores though is an apparently tighter coupling
of mutual
inductance from the wrapped-around coil meeting it's opposite end.
Maybe one
could tighten up the magnetic coupling even more in air-core inductors
by making
the windings come all the way around, and possibly even over-wrap the
head and tail
by a few turns...?

Arv
_._

Yes, but all that would do is increase the Q a bit, and you could cause some sort of buck-boost effect that would encourage a secondary resonance by overlapping turns. Look at the problems power transformers have with improper winding. And they laminate cores for a reason.

If one calculates the A_L of any medium, what has one really done? They have discovered the magnetic susceptance of that particular medium. Faraday worked that out long ago, I think.

But the radio engineers learned early on that overlapping ends of a coil produce strange effects sometimes, as did inserting a "foreign" medium into it. It was decided that the more uniform the coil, the better the actual result. So it is better to not complicate things too much. The use of iron cores and ferrites was to reduce the size of the device (apparently always a good thing). :) But that introduced all kinds of secondary effects up to and including saturation. Oh, well...

But there is no reason that one could not work out a more-or-less standard way of calculating inductance with any medium. One just has to be aware that it changes with the change in the actual magnetic field. If the field change is uniform, so is A_L. If not, well...

Anyway, I like it! Keep it up.


john
AD5YE

Re: Bitx Ver.1 Original -40 m???

Mark <huitmarmottes@...>
 

Hi :-)

I like the pvc pipe ideas for air core toroids. I don't know the size of tap washers originally used, but with the pipe you can get a nice large diameter and thickness so your air-inductor will require a lot less turns.

The advantage of the fewer turns needed for ferro-core inductors do count. With the finer wire and multiple turns needed to attain the inductance required for HF frequencies can lower the Q through skin and proximity effects.

To me, it's kind of a continuum for the cores. AT UHF/VHF you need lower inductance and ferro cores can become more easily saturated and experience increasing hysteresis losses, so air cores rule. At HF, ferro cores do have their advantages as the losses are linear with frequency so much less, and the relatively much fewer turns can result in higher Q through lower skin and proximity effect losses.

If you have space, you can put in some of those litz wire spider wound creations they use in crystal radios hi hi. But if going air-core toroidal, I think the pvc pipe (or large wood or plastic bead) forms John and Arv mentioned are the way to go.

Since scavenged ferro-cores are free and getting more plentiful now (better than ending up in a landfill!) though I think they are good to try too.

Cheers,

Mark.

--- In BITX20@..., "iam74@..." <iam74@...> wrote:



--- In BITX20@..., Arv Evans <arvid.evans@> wrote:

Juan Carlos - WJ6C

Don't give up on the non-metallic toroid inductors and transformers.
Using larger
diameter tap washers or stacking multiple tap washers is a possibility
if one does
not want to use an unreasonable number of turns for a given inductance.

It is possible to use plastic beads, wooden beads, lengths of plastic
tube or plastic pipe,
and many other insulators as the former for non-metallic toroidal
cores. If the inductor
is made in a toroidal form, most of the magnetic field is still
concentrated in the
center of the unit, with significantly less magnetic field external to
the inductor than
would be experienced with a conventional solenoid shaped inductor.

Using a known frequency signal source (i.e. a crystal oscillator) it is
relatively easy
to evaluate an unknown air-cored or plastic cored toroidal inductance.
The procedure
for minimum test equipment evaluation of non-metallic toroid cores is to
lightly couple
(1 to 2 pf) a signal source to a "test inductance" with a variable
capacitor across that
winding. Then with a lightly coupled (1 to 2 pf) oscilloscope or
detector and meter
one can determine the resonance of that winding and from that it's
inductance and
capacitance at resonance. Once you know the L, C, & F values versus
number of turns,
you can compute the effective AL factor for that particular form size
and shape.
Knowing the AL factor you can now calculate the number of turns required
for any
particular inductance that might be needed. Inductance =(Al * (Turns *
Turns))

Non-metallic core toroidal shaped inductors tend to be fairly high Q and
to have
low internal distributed capacitance. When evaluating a test-winding
for resonance
it is possible to tune the signal generator off-resonance above and
below the resonant
frequency to determine the -3 db points. From this it is possible to
predict the
Q-factor for that winding and that wire diameter. Q=(Fcenter / bandwidth)

One often overlooked benefit of non-metallic toroid cores is that they
don't have
power and linearity limits that occur at core saturation...they don't
saturate!

For HF use in ham radio we seem to have become dependent on metallic core
toroids, possibly because manufacturer provided tables easily tell us
how many
turns are needed for a particular inductance value. This does not mean
that these
type cores are the most efficient or most effective for all situations.

In the early years of BITX20 construction (before kits) many of us
experimented
with tap washers, wooden beads, PVC pipe sections, and several other
convenient
forms for our air-core toroids, with great success. For those in areas
where ferrite
cores are not readily available, the use of non-metallic core material
is still a
viable and effective option. The BITX20 design was started by Farhan
VU3ESE as
a rig that could be built with "found" salvage and surplus materials.
He proved that
this works, and it still works today.

Arv - K7HKL

I think you've got the right idea, Arv. The simplest way to make a toroid is with a small piece of pvc pipe, say 1" in diameter and 3/8" thick. Cut a slit in it lengthwise and it is easy to wind a toroid around the form; you don't even have to worry about "threading" it through the hole. And the slit is no problem since the coil you want should not occupy the last 30 deg. of space around the bottom anyway.

It would be a simple matter to construct several with various turns and determine the inductance standards. If you have a frequency counter, put them in a rigged "standard" oscillator and calibrate the lot. That data should give you the information necessary to build almost anything you need at will. If you need more turns for a given inductance, use smaller wire.

And the toroid properties would be preserved even though the core is not metallic. The only advantage of a metallic core is the fewer number of turns needed for a given inductance, provided the composition of the core is good for your application in the first place!


john
AD5YE

Re: Hendricks BitX17A almost alive thanks to KC0WOX's videos..

Arv Evans
 

Bill

Design of the BITXxxA VFO is such that the output is dependent on the
resonant
loop impedance of the frequency determining components. This means that if
you use a very small capacitor for C-37 it will decrease the amount of
oscillator
feedback and thus reduce the VFO output.

This is viewable by observing the VFO output as you change C-38 from
maximum
to minimum capacitance. You will see the VFO output decrease as C-38
value is
decreased. This is also visible if you operate Jim W4ENE's VFO design
tool all the
way to generation and running of the LT-Spice simulation. It shows the
VFO output
voltage at minimum C-38 and at maximum C-38. The two voltages will be
different,
with the difference being relative to C-38 impedance as part of the
feedback loop
needed to sustain oscillation.

By decreasing inductance in L-7 and compensating by increasing
capacitance in
C-15 you can increase feedback and thus VFO output, but this then requires
re-calculating values for C-37 versus C-38 to maintain the band coverage
that
you desire. This is where Jim's program comes in handy because you can try
various combinations in the VFO circuit without having to melt so much
solder
or risk damaging your PCB.

Don't forget that you can also make small changes in the values of C-34 and
C-35 to adjust the feedback level, and thus the VFO output.

Arv
_._

On 01/24/2011 09:54 PM, William wrote:

Charles, Jim, Arv, and now Leonard..

..their support and Leonard's superlative videos have turned this Bitx
build into more than just a stuff-n-solder project. It is really cool
to learn while you earn, so to speak.

In any event, after navigating Leonard's show'n'tell, some minor
problems were found and it is aalmost ready to have the final PS
adjusted and peaked.Everything almost checks out through the bandpass
filter. (Most o-scope traces and voltages agree.)

One nagging question, however, to wit: there is nowhere near the
output from my VFO that Leonard's video shows he is getting on his
BitX20. His levels are about 1.5 V P-P whereas the same measurement on
mine is just a shade under 300 mV. This is with driving the radio with
500- and 2000-KHz audio at 50 mV. Of course, this trend continues on
through to the drain at Q20 (band pass filter output) where there's a
clean signal but only at about 120 mV.

I'll have to double back and see if there's an adjustment that can be
tweaked like adjust the BFO further up or down the XTAL filter slope
or something.

Just wanted to document the progress so far. The latest pictures can
be found in the "K6WHP's Obligatory.." album if there is an interest.

Any ideas or thoughts are greatly appreciated.

72,

Bill, k6whp

Re: Bitx Ver.1 Original -40 m???

Arv Evans
 

John

You have got the idea! Way back in the early days of BITX20 we were
playing with
PVC tubing with slots for quickly winding the turns. Now the math and
procedures
seem to be catching up with the mechanics to make this into an
interesting field of
play. It all started to come together for me when I realized that I
could calculate
an A_L value for air-core toroids, and from that calculate the number of
turns for
any inductance that was wound with that particular core dimension. I
wrote a
small Linux Shell-script program to do the math and it all seems to make
perfect
sense. :-)

Next step is to devise a way to use any non-magnetic core's
cross-sectional area to
predict the A_L for any inductor that is wound on it. Also have to take
into consideration
the dielectric constant of the core material, but to-date that seems to
play a relatively
minor role in actual inductance values.

One benefit of magnetic cores though is an apparently tighter coupling
of mutual
inductance from the wrapped-around coil meeting it's opposite end.
Maybe one
could tighten up the magnetic coupling even more in air-core inductors
by making
the windings come all the way around, and possibly even over-wrap the
head and tail
by a few turns...?

Arv
_._

On 01/24/2011 09:37 PM, iam74@... wrote:



--- In BITX20@... <mailto:BITX20%40yahoogroups.com>, Arv
Evans <arvid.evans@...> wrote:

Juan Carlos - WJ6C

Don't give up on the non-metallic toroid inductors and transformers.
Using larger
diameter tap washers or stacking multiple tap washers is a possibility
if one does
not want to use an unreasonable number of turns for a given inductance.

It is possible to use plastic beads, wooden beads, lengths of plastic
tube or plastic pipe,
and many other insulators as the former for non-metallic toroidal
cores. If the inductor
is made in a toroidal form, most of the magnetic field is still
concentrated in the
center of the unit, with significantly less magnetic field external to
the inductor than
would be experienced with a conventional solenoid shaped inductor.

Using a known frequency signal source (i.e. a crystal oscillator) it is
relatively easy
to evaluate an unknown air-cored or plastic cored toroidal inductance.
The procedure
for minimum test equipment evaluation of non-metallic toroid cores
is to
lightly couple
(1 to 2 pf) a signal source to a "test inductance" with a variable
capacitor across that
winding. Then with a lightly coupled (1 to 2 pf) oscilloscope or
detector and meter
one can determine the resonance of that winding and from that it's
inductance and
capacitance at resonance. Once you know the L, C, & F values versus
number of turns,
you can compute the effective AL factor for that particular form size
and shape.
Knowing the AL factor you can now calculate the number of turns
required
for any
particular inductance that might be needed. Inductance =(Al * (Turns *
Turns))

Non-metallic core toroidal shaped inductors tend to be fairly high Q
and
to have
low internal distributed capacitance. When evaluating a test-winding
for resonance
it is possible to tune the signal generator off-resonance above and
below the resonant
frequency to determine the -3 db points. From this it is possible to
predict the
Q-factor for that winding and that wire diameter. Q=(Fcenter /
bandwidth)

One often overlooked benefit of non-metallic toroid cores is that they
don't have
power and linearity limits that occur at core saturation...they don't
saturate!

For HF use in ham radio we seem to have become dependent on metallic
core
toroids, possibly because manufacturer provided tables easily tell us
how many
turns are needed for a particular inductance value. This does not mean
that these
type cores are the most efficient or most effective for all situations.

In the early years of BITX20 construction (before kits) many of us
experimented
with tap washers, wooden beads, PVC pipe sections, and several other
convenient
forms for our air-core toroids, with great success. For those in areas
where ferrite
cores are not readily available, the use of non-metallic core material
is still a
viable and effective option. The BITX20 design was started by Farhan
VU3ESE as
a rig that could be built with "found" salvage and surplus materials.
He proved that
this works, and it still works today.

Arv - K7HKL
I think you've got the right idea, Arv. The simplest way to make a
toroid is with a small piece of pvc pipe, say 1" in diameter and 3/8"
thick. Cut a slit in it lengthwise and it is easy to wind a toroid
around the form; you don't even have to worry about "threading" it
through the hole. And the slit is no problem since the coil you want
should not occupy the last 30 deg. of space around the bottom anyway.

It would be a simple matter to construct several with various turns
and determine the inductance standards. If you have a frequency
counter, put them in a rigged "standard" oscillator and calibrate the
lot. That data should give you the information necessary to build
almost anything you need at will. If you need more turns for a given
inductance, use smaller wire.

And the toroid properties would be preserved even though the core is
not metallic. The only advantage of a metallic core is the fewer
number of turns needed for a given inductance, provided the
composition of the core is good for your application in the first place!

john
AD5YE

Re: Another question reagarding OFV

John Backo
 

--- In BITX20@..., "linuxtech2003" <bruno.luciani@...> wrote:

Thanks John !!

Yes you are right the voltage that I am using
is of the vfo 9v , may be thats the problem

I try to use 12 v

Respect to PA , actually I get 10 watt more or less

so it is ok , but Sunil say that this fet can produce 15 watts

Bruno
For the IRF510 to get 10-15W, yes you can. But you are going to have to use a 24v supply or go to a 2-device push-pull amp, or both, to do it reasonably.

Download and study "The handyman's Guide to MOSFET "SWITCHED MODE" Amplifiers" by Paul Harden NA5N for an explanation of what is proper and what is not for these devices.

www.aoc.nrao.edu/~pharden/hobby/_CLASSDEF1.pdf

For the ordinary ham, Farhan's JBOT amplifier is much more reasonable to make and operate. It can easily be made to put out 20W or more with the proper transistors, especially at 40m and below. Use, for instance, the 2N3053, 2N3553, or 2SD612K.


john
AD5YE

Hendricks BitX17A almost alive thanks to KC0WOX's videos..

William <k6whp@...>
 

Charles, Jim, Arv, and now Leonard..

..their support and Leonard's superlative videos have turned this Bitx build into more than just a stuff-n-solder project. It is really cool to learn while you earn, so to speak.

In any event, after navigating Leonard's show'n'tell, some minor problems were found and it is aalmost ready to have the final PS adjusted and peaked.Everything almost checks out through the bandpass filter. (Most o-scope traces and voltages agree.)

One nagging question, however, to wit: there is nowhere near the output from my VFO that Leonard's video shows he is getting on his BitX20. His levels are about 1.5 V P-P whereas the same measurement on mine is just a shade under 300 mV. This is with driving the radio with 500- and 2000-KHz audio at 50 mV. Of course, this trend continues on through to the drain at Q20 (band pass filter output) where there's a clean signal but only at about 120 mV.

I'll have to double back and see if there's an adjustment that can be tweaked like adjust the BFO further up or down the XTAL filter slope or something.

Just wanted to document the progress so far. The latest pictures can be found in the "K6WHP's Obligatory.." album if there is an interest.

Any ideas or thoughts are greatly appreciated.

72,

Bill, k6whp

Re: Bitx Ver.1 Original -40 m???

John Backo
 

--- In BITX20@..., Arv Evans <arvid.evans@...> wrote:

Juan Carlos - WJ6C

Don't give up on the non-metallic toroid inductors and transformers.
Using larger
diameter tap washers or stacking multiple tap washers is a possibility
if one does
not want to use an unreasonable number of turns for a given inductance.

It is possible to use plastic beads, wooden beads, lengths of plastic
tube or plastic pipe,
and many other insulators as the former for non-metallic toroidal
cores. If the inductor
is made in a toroidal form, most of the magnetic field is still
concentrated in the
center of the unit, with significantly less magnetic field external to
the inductor than
would be experienced with a conventional solenoid shaped inductor.

Using a known frequency signal source (i.e. a crystal oscillator) it is
relatively easy
to evaluate an unknown air-cored or plastic cored toroidal inductance.
The procedure
for minimum test equipment evaluation of non-metallic toroid cores is to
lightly couple
(1 to 2 pf) a signal source to a "test inductance" with a variable
capacitor across that
winding. Then with a lightly coupled (1 to 2 pf) oscilloscope or
detector and meter
one can determine the resonance of that winding and from that it's
inductance and
capacitance at resonance. Once you know the L, C, & F values versus
number of turns,
you can compute the effective AL factor for that particular form size
and shape.
Knowing the AL factor you can now calculate the number of turns required
for any
particular inductance that might be needed. Inductance =(Al * (Turns *
Turns))

Non-metallic core toroidal shaped inductors tend to be fairly high Q and
to have
low internal distributed capacitance. When evaluating a test-winding
for resonance
it is possible to tune the signal generator off-resonance above and
below the resonant
frequency to determine the -3 db points. From this it is possible to
predict the
Q-factor for that winding and that wire diameter. Q=(Fcenter / bandwidth)

One often overlooked benefit of non-metallic toroid cores is that they
don't have
power and linearity limits that occur at core saturation...they don't
saturate!

For HF use in ham radio we seem to have become dependent on metallic core
toroids, possibly because manufacturer provided tables easily tell us
how many
turns are needed for a particular inductance value. This does not mean
that these
type cores are the most efficient or most effective for all situations.

In the early years of BITX20 construction (before kits) many of us
experimented
with tap washers, wooden beads, PVC pipe sections, and several other
convenient
forms for our air-core toroids, with great success. For those in areas
where ferrite
cores are not readily available, the use of non-metallic core material
is still a
viable and effective option. The BITX20 design was started by Farhan
VU3ESE as
a rig that could be built with "found" salvage and surplus materials.
He proved that
this works, and it still works today.

Arv - K7HKL

I think you've got the right idea, Arv. The simplest way to make a toroid is with a small piece of pvc pipe, say 1" in diameter and 3/8" thick. Cut a slit in it lengthwise and it is easy to wind a toroid around the form; you don't even have to worry about "threading" it through the hole. And the slit is no problem since the coil you want should not occupy the last 30 deg. of space around the bottom anyway.

It would be a simple matter to construct several with various turns and determine the inductance standards. If you have a frequency counter, put them in a rigged "standard" oscillator and calibrate the lot. That data should give you the information necessary to build almost anything you need at will. If you need more turns for a given inductance, use smaller wire.

And the toroid properties would be preserved even though the core is not metallic. The only advantage of a metallic core is the fewer number of turns needed for a given inductance, provided the composition of the core is good for your application in the first place!


john
AD5YE

Re: Bitx Ver.1 Original -40 m???

Mark <huitmarmottes@...>
 

Hi JC,

I think that is a great idea! You will just need to find a good way to advertise to get the word out about the charity. Once you get it going, I'm sure some here (me too) could contribute in some way by parts, or books, or funds.

Regarding the fluorescent bulb toroids. Yeah, I think it would be the same for ones from motherboards. The advantage for us as home brewers though, is that we don't always have to be so picky. With an L/C meter (or simple oscillator and counter) we can just adjust the number of turns for whatever our core material is (air, powdered iron, some kind of ferrite mix) to get the inductance that we want.

If I had a big batch of salvaged cores, I would just temporarily wind something like 10 turns on each, get the inductance, and the mark them with a color scheme with an approximate permeability rating. Then you it would be easier in the future to choose one that best matches your needs.

Cheers and 73's,

Mark.

--- In BITX20@..., Juan Carlos Berberena Glez <jcberberena@...> wrote:

Hi Mark
Let me tell you
In Cuba my friends collecting all the burned compact fluorescent light
bulbs, to get the small toroide
I do the same here and I have a collection of it, but for my surprise all
the items are complete different, the same size but different composition.
I have collected all the TV I see in my way and take the components with hot
air, simple and efficient, to finally to send then to CO.
We have the
World Amateur Radio Foundation Inc, here in Florida, and I have to complete
the FORM 501(c)3 with the IRS to be able to get money from donation like a
Charitable Organization.
After that We are planning to buy book and components to help guys in the
third world country like Cuba
At this time my budget is not large enough to buy and to gift

What do you think about this???
I am proud to be here and I believe in the generosity of this country,
73's
Jc

WJ6C ex/CO6BG



2011/1/24 Mark <huitmarmottes@...>



Sure Carlos!

Also, if you can get it out without breaking the bulb, I've heard that
compact fluorescent light bulbs also have a toroid in them. I have a dead
one at home I will try to break open its base tonight and see.

73's


Mark.

--- In BITX20@... <BITX20%40yahoogroups.com>, Juan Carlos
Berberena Glez <jcberberena@> wrote:

Thank You Mark
I am sending them a L/C meter to find the inductance more easy
At this time I am not sure what will be resource available for them, but
it's(LPF) not a big deal
Maybe in the the Russian radio receiver they can pick it up
73's
Jc

2011/1/24 Mark <huitmarmottes@>



Hi Carlos,

I'm not sure of the supply in Cuba, but if they can find a supply of
dead
computers, there are normally a few toroid cores on the motherboards.
Their
permeability will vary as sometimes they are powdered iron and
sometimes
different kinds of ferrite, but they could try to find a batch of
scavenge
all the same kind. Sometimes you can tell by the number of windings
(typically there will be less turns on the ferrite core types).

Then they would just have to experiment around a bit with winding to
find
the correct inductance. Certainly it will be a lot less windings than
tap
washer coils!

Cheers!

Mark.


--- In BITX20@... <BITX20%40yahoogroups.com> <BITX20%
40yahoogroups.com>, Juan Carlos
Berberena Glez <jcberberena@> wrote:

Thanks John

The reason for that is to follow the original idea to avoid use
toroides
I am helping some Cuban Amateur to build it, and it is the best
project
for
them meanwhile the economical situation go up.
73's
WJ6C exCO6BG



2011/1/24 iam74@ <iam74@>





--- In BITX20@... <BITX20%40yahoogroups.com> <BITX20%
40yahoogroups.com> <BITX20%

40yahoogroups.com>, Juan Carlos

Berberena Glez <jcberberena@> wrote:

Hi Every one
I want to run the original design in 40m,
What will be the best combination L/C for the LPF using the tap
washer
(120pF-4uH)
I was thinking to double the number of turn and the total
capacity
until
reach 120pF.
Any suggestion?




<BITX20%40yahoogroups.com>

--
Juan Carlos Berberena
Juan,

You have to keep the same relative impedances when you change to
another
band. If your original is for 20m or 14 Mhz, then double the values
of
all
your components and the system should work for 40m or 7 Mhz. It is
easy
to
do that with capacitors, but inductance does not double with a
simple
doubling of the turns.

However, you will know the target inductance that you need, and you
should
be able to find it experimentally. It will probably be somewhere
around
70%
more turns for 40m than for 20m, but that is not guaranteed for
tap-washer
scramble wound coils.

john
AD5YE




--
Juan Carlos Berberena


[Non-text portions of this message have been removed]



--
Juan Carlos Berberena






--
Juan Carlos Berberena


[Non-text portions of this message have been removed]

Re: Bitx Ver.1 Original -40 m???

linuxtech2003
 

--- In BITX20@..., Juan Carlos Berberena Glez <jcberberena@...> wrote:

Hi Mark
Let me tell you
In Cuba my friends collecting all the burned compact fluorescent light
bulbs, to get the small toroide
I do the same here and I have a collection of it, but for my surprise all
the items are complete different, the same size but different composition.
I have collected all the TV I see in my way and take the components with hot
air, simple and efficient, to finally to send then to CO.
We have the
World Amateur Radio Foundation Inc, here in Florida, and I have to complete
the FORM 501(c)3 with the IRS to be able to get money from donation like a
Charitable Organization.
After that We are planning to buy book and components to help guys in the
third world country like Cuba
At this time my budget is not large enough to buy and to gift

What do you think about this???
I am proud to be here and I believe in the generosity of this country,
73's
Jc

WJ6C ex/CO6BG



2011/1/24 Mark <huitmarmottes@...>



Sure Carlos!

Also, if you can get it out without breaking the bulb, I've heard that
compact fluorescent light bulbs also have a toroid in them. I have a dead
one at home I will try to break open its base tonight and see.

73's


Mark.

--- In BITX20@... <BITX20%40yahoogroups.com>, Juan Carlos
Berberena Glez <jcberberena@> wrote:

Thank You Mark
I am sending them a L/C meter to find the inductance more easy
At this time I am not sure what will be resource available for them, but
it's(LPF) not a big deal
Maybe in the the Russian radio receiver they can pick it up
73's
Jc

2011/1/24 Mark <huitmarmottes@>



Hi Carlos,

I'm not sure of the supply in Cuba, but if they can find a supply of
dead
computers, there are normally a few toroid cores on the motherboards.
Their
permeability will vary as sometimes they are powdered iron and
sometimes
different kinds of ferrite, but they could try to find a batch of
scavenge
all the same kind. Sometimes you can tell by the number of windings
(typically there will be less turns on the ferrite core types).

Then they would just have to experiment around a bit with winding to
find
the correct inductance. Certainly it will be a lot less windings than
tap
washer coils!

Cheers!

Mark.


--- In BITX20@... <BITX20%40yahoogroups.com> <BITX20%
40yahoogroups.com>, Juan Carlos
Berberena Glez <jcberberena@> wrote:

Thanks John

The reason for that is to follow the original idea to avoid use
toroides
I am helping some Cuban Amateur to build it, and it is the best
project
for
them meanwhile the economical situation go up.
73's
WJ6C exCO6BG



2011/1/24 iam74@ <iam74@>





--- In BITX20@... <BITX20%40yahoogroups.com> <BITX20%
40yahoogroups.com> <BITX20%

40yahoogroups.com>, Juan Carlos

Berberena Glez <jcberberena@> wrote:

Hi Every one
I want to run the original design in 40m,
What will be the best combination L/C for the LPF using the tap
washer
(120pF-4uH)
I was thinking to double the number of turn and the total
capacity
until
reach 120pF.
Any suggestion?




<BITX20%40yahoogroups.com>

--
Juan Carlos Berberena
Juan,

You have to keep the same relative impedances when you change to
another
band. If your original is for 20m or 14 Mhz, then double the values
of
all
your components and the system should work for 40m or 7 Mhz. It is
easy
to
do that with capacitors, but inductance does not double with a
simple
doubling of the turns.

However, you will know the target inductance that you need, and you
should
be able to find it experimentally. It will probably be somewhere
around
70%
more turns for 40m than for 20m, but that is not guaranteed for
tap-washer
scramble wound coils.

john
AD5YE




--
Juan Carlos Berberena






--
Juan Carlos Berberena


[Non-text portions of this message have been removed]



--
Juan Carlos Berberena


[Non-text portions of this message have been removed]

Re: Bitx Ver.1 Original -40 m???

linuxtech2003
 

Carlos , another font of toroids are electronic lamps for ilumination
here in argentina , I don't know if in cuba is the same

Bruno

--- In BITX20@..., "Mark" <huitmarmottes@...> wrote:

Hi Carlos,

I'm not sure of the supply in Cuba, but if they can find a supply of dead computers, there are normally a few toroid cores on the motherboards. Their permeability will vary as sometimes they are powdered iron and sometimes different kinds of ferrite, but they could try to find a batch of scavenge all the same kind. Sometimes you can tell by the number of windings (typically there will be less turns on the ferrite core types).

Re: Bitx Ver.1 Original -40 m???

Arv Evans
 

Mark & Juan Carlos

<http://qrp.webhop.net/Hints_and_Tips/cflampsurplusandsalvage.html>

shows some information regarding what you may find inside a CFL light bulb.

Arv
_._

On 01/24/2011 05:40 PM, Mark wrote:

Sure Carlos!

Also, if you can get it out without breaking the bulb, I've heard that
compact fluorescent light bulbs also have a toroid in them. I have a
dead one at home I will try to break open its base tonight and see.

73's

Mark.

--- In BITX20@... <mailto:BITX20%40yahoogroups.com>, Juan
Carlos Berberena Glez <jcberberena@...> wrote:

Thank You Mark
I am sending them a L/C meter to find the inductance more easy
At this time I am not sure what will be resource available for them, but
it's(LPF) not a big deal
Maybe in the the Russian radio receiver they can pick it up
73's
Jc

2011/1/24 Mark <huitmarmottes@...>



Hi Carlos,

I'm not sure of the supply in Cuba, but if they can find a supply
of dead
computers, there are normally a few toroid cores on the
motherboards. Their
permeability will vary as sometimes they are powdered iron and
sometimes
different kinds of ferrite, but they could try to find a batch of
scavenge
all the same kind. Sometimes you can tell by the number of windings
(typically there will be less turns on the ferrite core types).

Then they would just have to experiment around a bit with winding
to find
the correct inductance. Certainly it will be a lot less windings
than tap
washer coils!

Cheers!

Mark.


--- In BITX20@... <mailto:BITX20%40yahoogroups.com>
<BITX20%40yahoogroups.com>, Juan Carlos
Berberena Glez <jcberberena@> wrote:

Thanks John

The reason for that is to follow the original idea to avoid use
toroides
I am helping some Cuban Amateur to build it, and it is the best
project
for
them meanwhile the economical situation go up.
73's
WJ6C exCO6BG



2011/1/24 iam74@ <iam74@>





--- In BITX20@...
<mailto:BITX20%40yahoogroups.com> <BITX20%40yahoogroups.com> <BITX20%
40yahoogroups.com>, Juan Carlos

Berberena Glez <jcberberena@> wrote:

Hi Every one
I want to run the original design in 40m,
What will be the best combination L/C for the LPF using the tap
washer
(120pF-4uH)
I was thinking to double the number of turn and the total
capacity
until
reach 120pF.
Any suggestion?




<BITX20%40yahoogroups.com>

--
Juan Carlos Berberena
Juan,

You have to keep the same relative impedances when you change to
another
band. If your original is for 20m or 14 Mhz, then double the
values of
all
your components and the system should work for 40m or 7 Mhz.
It is easy
to
do that with capacitors, but inductance does not double with a
simple
doubling of the turns.

However, you will know the target inductance that you need,
and you
should
be able to find it experimentally. It will probably be
somewhere around
70%
more turns for 40m than for 20m, but that is not guaranteed for
tap-washer
scramble wound coils.

john
AD5YE




--
Juan Carlos Berberena






--
Juan Carlos Berberena



Re: Bitx Ver.1 Original -40 m???

Arv Evans
 

Juan Carlos - WJ6C

Don't give up on the non-metallic toroid inductors and transformers.
Using larger
diameter tap washers or stacking multiple tap washers is a possibility
if one does
not want to use an unreasonable number of turns for a given inductance.

It is possible to use plastic beads, wooden beads, lengths of plastic
tube or plastic pipe,
and many other insulators as the former for non-metallic toroidal
cores. If the inductor
is made in a toroidal form, most of the magnetic field is still
concentrated in the
center of the unit, with significantly less magnetic field external to
the inductor than
would be experienced with a conventional solenoid shaped inductor.

Using a known frequency signal source (i.e. a crystal oscillator) it is
relatively easy
to evaluate an unknown air-cored or plastic cored toroidal inductance.
The procedure
for minimum test equipment evaluation of non-metallic toroid cores is to
lightly couple
(1 to 2 pf) a signal source to a "test inductance" with a variable
capacitor across that
winding. Then with a lightly coupled (1 to 2 pf) oscilloscope or
detector and meter
one can determine the resonance of that winding and from that it's
inductance and
capacitance at resonance. Once you know the L, C, & F values versus
number of turns,
you can compute the effective AL factor for that particular form size
and shape.
Knowing the AL factor you can now calculate the number of turns required
for any
particular inductance that might be needed. Inductance =(Al * (Turns *
Turns))

Non-metallic core toroidal shaped inductors tend to be fairly high Q and
to have
low internal distributed capacitance. When evaluating a test-winding
for resonance
it is possible to tune the signal generator off-resonance above and
below the resonant
frequency to determine the -3 db points. From this it is possible to
predict the
Q-factor for that winding and that wire diameter. Q=(Fcenter / bandwidth)

One often overlooked benefit of non-metallic toroid cores is that they
don't have
power and linearity limits that occur at core saturation...they don't
saturate!

For HF use in ham radio we seem to have become dependent on metallic core
toroids, possibly because manufacturer provided tables easily tell us
how many
turns are needed for a particular inductance value. This does not mean
that these
type cores are the most efficient or most effective for all situations.

In the early years of BITX20 construction (before kits) many of us
experimented
with tap washers, wooden beads, PVC pipe sections, and several other
convenient
forms for our air-core toroids, with great success. For those in areas
where ferrite
cores are not readily available, the use of non-metallic core material
is still a
viable and effective option. The BITX20 design was started by Farhan
VU3ESE as
a rig that could be built with "found" salvage and surplus materials.
He proved that
this works, and it still works today.

Arv - K7HKL

On 01/24/2011 05:25 PM, Juan Carlos Berberena Glez wrote:
Thank You Mark
I am sending them a L/C meter to find the inductance more easy
At this time I am not sure what will be resource available for them, but
it's(LPF) not a big deal
Maybe in the the Russian radio receiver they can pick it up
73's
Jc

2011/1/24 Mark<huitmarmottes@...>


Hi Carlos,

I'm not sure of the supply in Cuba, but if they can find a supply of dead
computers, there are normally a few toroid cores on the motherboards. Their
permeability will vary as sometimes they are powdered iron and sometimes
different kinds of ferrite, but they could try to find a batch of scavenge
all the same kind. Sometimes you can tell by the number of windings
(typically there will be less turns on the ferrite core types).

Then they would just have to experiment around a bit with winding to find
the correct inductance. Certainly it will be a lot less windings than tap
washer coils!

Cheers!

Mark.


--- In BITX20@...<BITX20%40yahoogroups.com>, Juan Carlos
Berberena Glez<jcberberena@...> wrote:
Thanks John

The reason for that is to follow the original idea to avoid use toroides
I am helping some Cuban Amateur to build it, and it is the best project
for
them meanwhile the economical situation go up.
73's
WJ6C exCO6BG



2011/1/24 iam74@...<iam74@...>




--- In BITX20@...<BITX20%40yahoogroups.com> <BITX20%
40yahoogroups.com>, Juan Carlos

Berberena Glez<jcberberena@> wrote:
Hi Every one
I want to run the original design in 40m,
What will be the best combination L/C for the LPF using the tap
washer
(120pF-4uH)
I was thinking to double the number of turn and the total capacity
until
reach 120pF.
Any suggestion?




<BITX20%40yahoogroups.com>

--
Juan Carlos Berberena
Juan,

You have to keep the same relative impedances when you change to
another
band. If your original is for 20m or 14 Mhz, then double the values of
all
your components and the system should work for 40m or 7 Mhz. It is easy
to
do that with capacitors, but inductance does not double with a simple
doubling of the turns.

However, you will know the target inductance that you need, and you
should
be able to find it experimentally. It will probably be somewhere around
70%
more turns for 40m than for 20m, but that is not guaranteed for
tap-washer
scramble wound coils.

john
AD5YE



--
Juan Carlos Berberena



Re: Another question reagarding OFV

linuxtech2003
 

Thanks John !!

Yes you are wright the voltage that I am using
is of the vfo 9v , may be thats the problem

I try to use 12 v

Respect to PA , actually I get 10 watt more or less

so it is ok , but Sunil say that this fet can produce 15 watts

Bruno

--- In BITX20@..., "iam74@..." <iam74@...> wrote:






--- In BITX20@..., "linuxtech2003" <bruno.luciani@> wrote:

Another problem that I have is my OFV is not covering
all 20 mtr band

only from 14.000 to 14.230

I am using Varicap mod , and I try diferent values to serial capacitor
actually 1000 pf , but nathing change , and my Varicap is a 1SV149

It have a good capacity

Any Idea ?


And which is the maximun power that can be obtained using only one
IRF510 ?

Bruno
Bruno

Hmmm... That varicap has a range from ~30pf to ~540pf and it should work. Note however that the voltage range for that is from 1v to 12v.

You have the lower end of the band covered. It would seem off-hand that you are not raising the voltage on the varicap high enough to bring its lower value capacitance into play.

Check the voltage range at the varicap and see what its range actually is.

If it goes from ~2v to ~10v then change the coupling capacitor to a lower value.

If not, then look to changing the voltage divider feeding the varicap to give it a proper range.

You are using 1000 pf and that may be too high. There is probably an iteration between the coupling capacitor and resistance on the voltage divider feeding the varicap. You will need to experiment to find the values that will give you the tuning range you want.


The IRF510 is best driven to 5-6W using 12v as the drain supply. You can get more out of it, but you will have to use a higher voltage, 18v or 24v.

The gate voltage should be around 3.5-4v to achieve proper "linear" operation. Every IRF510 device is different, and you may have to burn a few up before you find the best conditions for your rig.


john
AD5YE

Re: Bitx Ver.1 Original -40 m???

Juan Carlos Berberena Glez <jcberberena@...>
 

Hi Mark
Let me tell you
In Cuba my friends collecting all the burned compact fluorescent light
bulbs, to get the small toroide
I do the same here and I have a collection of it, but for my surprise all
the items are complete different, the same size but different composition.
I have collected all the TV I see in my way and take the components with hot
air, simple and efficient, to finally to send then to CO.
We have the
World Amateur Radio Foundation Inc, here in Florida, and I have to complete
the FORM 501(c)3 with the IRS to be able to get money from donation like a
Charitable Organization.
After that We are planning to buy book and components to help guys in the
third world country like Cuba
At this time my budget is not large enough to buy and to gift

What do you think about this???
I am proud to be here and I believe in the generosity of this country,
73's
Jc

WJ6C ex/CO6BG



2011/1/24 Mark <huitmarmottes@...>



Sure Carlos!

Also, if you can get it out without breaking the bulb, I've heard that
compact fluorescent light bulbs also have a toroid in them. I have a dead
one at home I will try to break open its base tonight and see.

73's


Mark.

--- In BITX20@... <BITX20%40yahoogroups.com>, Juan Carlos
Berberena Glez <jcberberena@...> wrote:

Thank You Mark
I am sending them a L/C meter to find the inductance more easy
At this time I am not sure what will be resource available for them, but
it's(LPF) not a big deal
Maybe in the the Russian radio receiver they can pick it up
73's
Jc

2011/1/24 Mark <huitmarmottes@...>



Hi Carlos,

I'm not sure of the supply in Cuba, but if they can find a supply of
dead
computers, there are normally a few toroid cores on the motherboards.
Their
permeability will vary as sometimes they are powdered iron and
sometimes
different kinds of ferrite, but they could try to find a batch of
scavenge
all the same kind. Sometimes you can tell by the number of windings
(typically there will be less turns on the ferrite core types).

Then they would just have to experiment around a bit with winding to
find
the correct inductance. Certainly it will be a lot less windings than
tap
washer coils!

Cheers!

Mark.


--- In BITX20@... <BITX20%40yahoogroups.com> <BITX20%
40yahoogroups.com>, Juan Carlos
Berberena Glez <jcberberena@> wrote:

Thanks John

The reason for that is to follow the original idea to avoid use
toroides
I am helping some Cuban Amateur to build it, and it is the best
project
for
them meanwhile the economical situation go up.
73's
WJ6C exCO6BG



2011/1/24 iam74@ <iam74@>





--- In BITX20@... <BITX20%40yahoogroups.com> <BITX20%
40yahoogroups.com> <BITX20%

40yahoogroups.com>, Juan Carlos

Berberena Glez <jcberberena@> wrote:

Hi Every one
I want to run the original design in 40m,
What will be the best combination L/C for the LPF using the tap
washer
(120pF-4uH)
I was thinking to double the number of turn and the total
capacity
until
reach 120pF.
Any suggestion?




<BITX20%40yahoogroups.com>

--
Juan Carlos Berberena
Juan,

You have to keep the same relative impedances when you change to
another
band. If your original is for 20m or 14 Mhz, then double the values
of
all
your components and the system should work for 40m or 7 Mhz. It is
easy
to
do that with capacitors, but inductance does not double with a
simple
doubling of the turns.

However, you will know the target inductance that you need, and you
should
be able to find it experimentally. It will probably be somewhere
around
70%
more turns for 40m than for 20m, but that is not guaranteed for
tap-washer
scramble wound coils.

john
AD5YE




--
Juan Carlos Berberena


[Non-text portions of this message have been removed]



--
Juan Carlos Berberena


[Non-text portions of this message have been removed]



--
Juan Carlos Berberena


[Non-text portions of this message have been removed]

Re: Bitx Ver.1 Original -40 m???

Mark <huitmarmottes@...>
 

Sure Carlos!

Also, if you can get it out without breaking the bulb, I've heard that compact fluorescent light bulbs also have a toroid in them. I have a dead one at home I will try to break open its base tonight and see.

73's

Mark.

--- In BITX20@..., Juan Carlos Berberena Glez <jcberberena@...> wrote:

Thank You Mark
I am sending them a L/C meter to find the inductance more easy
At this time I am not sure what will be resource available for them, but
it's(LPF) not a big deal
Maybe in the the Russian radio receiver they can pick it up
73's
Jc

2011/1/24 Mark <huitmarmottes@...>



Hi Carlos,

I'm not sure of the supply in Cuba, but if they can find a supply of dead
computers, there are normally a few toroid cores on the motherboards. Their
permeability will vary as sometimes they are powdered iron and sometimes
different kinds of ferrite, but they could try to find a batch of scavenge
all the same kind. Sometimes you can tell by the number of windings
(typically there will be less turns on the ferrite core types).

Then they would just have to experiment around a bit with winding to find
the correct inductance. Certainly it will be a lot less windings than tap
washer coils!

Cheers!

Mark.


--- In BITX20@... <BITX20%40yahoogroups.com>, Juan Carlos
Berberena Glez <jcberberena@> wrote:

Thanks John

The reason for that is to follow the original idea to avoid use toroides
I am helping some Cuban Amateur to build it, and it is the best project
for
them meanwhile the economical situation go up.
73's
WJ6C exCO6BG



2011/1/24 iam74@ <iam74@>





--- In BITX20@... <BITX20%40yahoogroups.com> <BITX20%
40yahoogroups.com>, Juan Carlos

Berberena Glez <jcberberena@> wrote:

Hi Every one
I want to run the original design in 40m,
What will be the best combination L/C for the LPF using the tap
washer
(120pF-4uH)
I was thinking to double the number of turn and the total capacity
until
reach 120pF.
Any suggestion?




<BITX20%40yahoogroups.com>

--
Juan Carlos Berberena
Juan,

You have to keep the same relative impedances when you change to
another
band. If your original is for 20m or 14 Mhz, then double the values of
all
your components and the system should work for 40m or 7 Mhz. It is easy
to
do that with capacitors, but inductance does not double with a simple
doubling of the turns.

However, you will know the target inductance that you need, and you
should
be able to find it experimentally. It will probably be somewhere around
70%
more turns for 40m than for 20m, but that is not guaranteed for
tap-washer
scramble wound coils.

john
AD5YE




--
Juan Carlos Berberena


[Non-text portions of this message have been removed]



--
Juan Carlos Berberena