开云体育

Agreed.

Steve

--- qrpbear <qrpbear@...> wrote:

Steve,

Personally I don't think we should get involved with this kind of
discussion here. ... snip....

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Steve,

I got the motors out this morning. Two 7.5 degree steppers and one
conventional motor (rpm??). I was thinking more along the lines of
coupling through two 6:1 epicyclic ball drives to the capacitor. That
should give me about 0.21 degrees per step. Might be fine enough for
government work. I'll still have to build a controller of course.

I'll check out the Electronics 101 group.

73,

'Bear' NH7SR

--- In loopantennas@..., Steve Greenfield
<alienrelics@y...> wrote:

--- qrpbear <qrpbear@y...> wrote:

While walking home from the bus stop yesterday I encountered an
HP
printer that someone had thrown away. Naturally I snagged that
puppy!
I've been thinking about using the stepper motors out of it for
remote tuning drive for loop capacitors.

Have any of you folks tried steppers from old printers? Anything
special I should look out for?

There is a stepper motor driver list, but it's rather dead and
starting to get taken over by spammers.

You might also try the Electronics_101 list, it is very active.



I don't think you will be happy with the stepper connected directly
to the tuning cap. It's probably 200 steps per rev, or 1.8 degrees
per step. Half stepping won't do you any good unless you intend on
leaving the stepper powered up all the time.

So you'll want to try and use the gears. Scanners and dot matrix
printers are another source of already geared-down steppers. In
fact, some scanners use a stiff string to move the scanning head,
so you could perhaps use it with a tuning cap taken from an old
dial radio.

=====
Steve Greenfield // Digital photography, scanning,
Polymorph Digital Photography // retouching, and photomorphing
253-318-2473 voice // to your specs.
polymorph@p... //
// Based in Tacoma, WA, USA




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Steve,

Personally I don't think we should get involved with this kind of
discussion here. It can't lead to anything constructive. Best to just
let this play itself out somewhere else.

Some things are simply best left ignored.

73,

'Bear' NH7SR

Bruce,

Curious... that goes contrary to my intuition also. It has always
been one of the "laws" of coil winding that best Q is obtained in
solenoid coils when the diameter to length ratio is square (1:1).

Ah... I just remembered best Q is with the diameter to length ratio
at 1:1 or greater! It still seems, though, that a solenoid type
multiturn loop with very wide spacing between turns should exhibit a
larger capture area due to its 3D form factor. Possibly it does but
it may be a case of diminishing returns once one has passed the one-
wire-diameter spacing rule.

I think I'll add that to my "build this someday" list. Mebbe a 3-turn
2' diameter with 1' between turns. I could always tell people it's a
new kind of Dreamcatcher... especially after I hang some feathers on
it.

My take on the capacitors is that they seem to be related to the eras
in which radios were built. Prior to the introduction of the All
American Five most radios used external antennas. The RF/Mixer stages
commonly used values as high as 500 pF. With the All American Five
the use of an oval spiral wound loop on the back of the radio became
common as did the 365 pF capacitor. With the introduction of ferrite
bars we began to see 220 pF capacitors being used for tuning. I think
the shift had more to do with the available inductance in a given
space than any other factor. Higher inductance requiring less
capacitance and exhibiting better Q (more signal voltage) resulting
in the ability to simplify design and reduce parts count.

73,

'Bear' NH7SR

--- In loopantennas@..., "Bruce Carter" <brucec@m...>
wrote:

Contrary to my intuition, closely spaced windings seem to vastly
increase the Q of the antenna. I, too thought about the capture
volume, but then the capture volume of a spiral loop would be

zero.

Aperature size appears to be everything in determining the
sensitivity of a loop. I made three identical 27 MHz loops, out of
10 guage, 20 guage, and 30 guage wire. All had the same
sensitivity, but the Q varied.

I have not researched the inter-winding capacitance question, but I
am beginning to suspect it doesn't have the effect I first

assumed.

It seems to be much easier to encompass the whole band with a 9 to
250 pF tuning capacitor than a 9 to 365 or 9 to 500 pF capacitor.
Again - counter intuitive, but why did radio manufacturers make the
change? Wire is cheap compared to tuning capacitors. Especially
when the first 9 to 250 pF capacitors were probably special order.
I will get to the bottom of it when I have time. For now, loops
made of 24 guage hookup wire, turns wound flush, on large styrofoam
forms are light weight, easy to make, have fantastic Q's, and span
the whole band. I may get around to posting articles soon, plus
updating a lot of my old ones.

--- In loopantennas@..., "qrpbear" <qrpbear@y...> wrote:

Another thing that keeps floating up from the depths of my
subconscious...

How would a multi-turn loop having space between turns a

significant

percentage of the loop diameter work relative to one that has

closer

spacing? For instance, a 2-turn 36" diameter loop with 12"

between

turns. My instincts tell me that there would be an increase in

the

physical capture area of the loop due to its taking on a more 3-D
profile. This would lead to higher performance than a close-

spaced

loop winding. How much increase in performance? Would there be an
optimal spacing? What about spacing equal to loop diameter?

Hmmm... obviously I need more copper... a LOT more! Uhh... got

any

spare capacitors?

73,

'Bear' NH7SR

--- qrpbear <qrpbear@...> wrote:

While walking home from the bus stop yesterday I encountered an
HP
printer that someone had thrown away. Naturally I snagged that
puppy!
I've been thinking about using the stepper motors out of it for
remote tuning drive for loop capacitors.

Have any of you folks tried steppers from old printers? Anything
special I should look out for?

There is a stepper motor driver list, but it's rather dead and
starting to get taken over by spammers.

You might also try the Electronics_101 list, it is very active.



I don't think you will be happy with the stepper connected directly
to the tuning cap. It's probably 200 steps per rev, or 1.8 degrees
per step. Half stepping won't do you any good unless you intend on
leaving the stepper powered up all the time.

So you'll want to try and use the gears. Scanners and dot matrix
printers are another source of already geared-down steppers. In
fact, some scanners use a stiff string to move the scanning head,
so you could perhaps use it with a tuning cap taken from an old
dial radio.

=====
Steve Greenfield // Digital photography, scanning,
Polymorph Digital Photography // retouching, and photomorphing
253-318-2473 voice // to your specs.
polymorph@... //
// Based in Tacoma, WA, USA




__________________________________
Do you Yahoo!?
Friends. Fun. Try the all-new Yahoo! Messenger.

Got a strange IM from electronicdx:

alienrelics: Why did you kick me off your lists? What do you mean,
"put down by your members"? I don't control anyone, and I can't see
anything for you to be mad about.
alienrelics: What have I ever said to make you angry?
electronicdx: What I mean is that they are against me in a way, but
this talk is over. I will get you back in enough said. ok. :-<


This is a little disturbing. "get you back"?

Does anyone here personally know Adam?

Steve

Contrary to my intuition, closely spaced windings seem to vastly
increase the Q of the antenna. I, too thought about the capture
volume, but then the capture volume of a spiral loop would be zero.
Aperature size appears to be everything in determining the
sensitivity of a loop. I made three identical 27 MHz loops, out of
10 guage, 20 guage, and 30 guage wire. All had the same
sensitivity, but the Q varied.

I have not researched the inter-winding capacitance question, but I
am beginning to suspect it doesn't have the effect I first assumed.
It seems to be much easier to encompass the whole band with a 9 to
250 pF tuning capacitor than a 9 to 365 or 9 to 500 pF capacitor.
Again - counter intuitive, but why did radio manufacturers make the
change? Wire is cheap compared to tuning capacitors. Especially
when the first 9 to 250 pF capacitors were probably special order.
I will get to the bottom of it when I have time. For now, loops
made of 24 guage hookup wire, turns wound flush, on large styrofoam
forms are light weight, easy to make, have fantastic Q's, and span
the whole band. I may get around to posting articles soon, plus
updating a lot of my old ones.

--- In loopantennas@..., "qrpbear" <qrpbear@y...> wrote:

Another thing that keeps floating up from the depths of my
subconscious...

How would a multi-turn loop having space between turns a

significant

percentage of the loop diameter work relative to one that has

closer

spacing? For instance, a 2-turn 36" diameter loop with 12" between
turns. My instincts tell me that there would be an increase in the
physical capture area of the loop due to its taking on a more 3-D
profile. This would lead to higher performance than a close-spaced
loop winding. How much increase in performance? Would there be an
optimal spacing? What about spacing equal to loop diameter?

Hmmm... obviously I need more copper... a LOT more! Uhh... got any
spare capacitors?

73,

'Bear' NH7SR

While walking home from the bus stop yesterday I encountered an HP
printer that someone had thrown away. Naturally I snagged that puppy!
I've been thinking about using the stepper motors out of it for
remote tuning drive for loop capacitors.

Have any of you folks tried steppers from old printers? Anything
special I should look out for?

73,

'Bear' NH7SR

Another thing that keeps floating up from the depths of my
subconscious...

How would a multi-turn loop having space between turns a significant
percentage of the loop diameter work relative to one that has closer
spacing? For instance, a 2-turn 36" diameter loop with 12" between
turns. My instincts tell me that there would be an increase in the
physical capture area of the loop due to its taking on a more 3-D
profile. This would lead to higher performance than a close-spaced
loop winding. How much increase in performance? Would there be an
optimal spacing? What about spacing equal to loop diameter?

Hmmm... obviously I need more copper... a LOT more! Uhh... got any
spare capacitors?

73,

'Bear' NH7SR

A little something to start off some discussion here...

Back in 1993 Rod Newkirk, W9BRD, published an article entitled "Honey
I Shrunk the Loop" in QST magazine (July, 1993). For those without
access to the article, it described a multi-turn loop antenna with a
resonating capacitor inserted at the center of each turn. The
benefits of doing so were supposedly to reduce the voltage across
each of the capacitors and to make it easier to match to 50 ohm coax.

It seems to me that the same principle could be used to construct
a "bandpass" loop that would not require retuning within a certain
band of frequencies much wider than a single-tuned loop.

Have any of you folks built one of these? If so, how well did it
perform for you?

73,

'Bear' NH7SR

--- als_radios <aburzynski@...> wrote:

It's too bad things busted up into two groups, but I choose to
stay
with this one and leave the other. Hopefully this will grow to
becoming the excellent group that it was in the past.

I'm hoping! qrpbear has started things off, posting in Links and
Files.

Please don't mess with the colors. Green on blue on red on yellow
on
black is a bit hard to take. Leave it like it is, please. Thanks.

I agree, and I won't mess with the colors. I read most of my
Yahoogroups online, and I hate it when someone picks some awful low
contrast color scheme.

Steve, list-owner of the new loopantennas

=====
Steve Greenfield // Digital photography, scanning,
Polymorph Digital Photography // retouching, and photomorphing
253-318-2473 voice // to your specs.
polymorph@... //
// Based in Tacoma, WA, USA




__________________________________
Do you Yahoo!?
Friends. Fun. Try the all-new Yahoo! Messenger.

It's too bad things busted up into two groups, but I choose to stay
with this one and leave the other. Hopefully this will grow to
becoming the excellent group that it was in the past.

Please don't mess with the colors. Green on blue on red on yellow on
black is a bit hard to take. Leave it like it is, please. Thanks.

Al KA5JGV

Hi,

Thanks to whoever initiated the move to start over. I value the
discussions regarding loop antenna design, fabrication and use that
take place daily on this list and resent the actions of the previous
list moderator / owner to transfer my subscription without
discussion or consent to another group not at all to my liking.

Please do not hesitate to contact me off list for any additional
help or support that may be required to get this group going again.

Thanks and regards,

David Kent / k4uja

Hello,

This email message is a notification to let you know that
a file has been uploaded to the Files area of the loopantennas
group.

File : /Links.txt
Uploaded by : alienrelics <alienrelics@...>
Description : Until I get a chance to sort them out and put them in the Links folder, here are all the links I had saved.

You can access this file at the URL



To learn more about file sharing for your group, please visit



Regards,

alienrelics <alienrelics@...>

Hello,

This email message is a notification to let you know that
a file has been uploaded to the Files area of the loopantennas
group.

File : /ModeratorFiles/June072004IMfromElectronicDX.txt
Uploaded by : alienrelics <alienrelics@...>
Description : Afternoon of June 7th, I was in an IM conversation with ElectronicDX. I'm AlienRelics and my name is Steve Greenfield, and I'm list-owner of the new LoopAntennas list.

You can access this file at the URL



To learn more about file sharing for your group, please visit



Regards,

alienrelics <alienrelics@...>



.

Well, here is my first post that makes me a member. I still don't
know what is going on with two groups, but spam happens, and I think
Yahoo sells the addresses of these groups.

I suggest a more constructive way of having two groups is to have
one group for all the shielded loop enthusiasts and another for
unshielded. I find all the shielded loop postings a bit useless -
as my designs go for maximum sensitivity - NOT noise reduction. The
moment I try to use shielded anything to construct a loop - the
sensitivity plummets. DUH - I am shielding the wire that is
supposed to pick up the signal. Now - if I use the shield of the
coax as my signal wire, I get good performance again.

hello everyone

Scott

Hello,

This email message is a notification to let you know that
a file has been uploaded to the Files area of the loopantennas
group.

File : /ModeratorFiles/AboutLoopAntennas.txt
Uploaded by : alienrelics <alienrelics@...>
Description : About LoopAntennas list - not the same as the old LoopAntennas list.

You can access this file at the URL



To learn more about file sharing for your group, please visit



Regards,

alienrelics <alienrelics@...>

Some of you were set to No Email. I changed you to Special Notices so
everyone would get this. Please, feel free to change your settings
back to No Email. I'm the only one who can send out as a Special
Notice, and I don't typically use it much.

Here's the skinny- I'm not the moderator of the old LoopAntennas. I'm
the moderator of the new LoopAntennas.

What happened: I got ElectronicDX's special notice earlier today,
threatening to shut down the list. I sent a reply, it bounced, I tried
to go to the list, Yahoogroups said no such list!

So after thinking about it for a few hours, I started up a Group as
LoopAntennas. I figured I'll start collecting links and files and
information where I don't have to worry about it getting deleted.

I'm list-owner or moderator of 15 lists, with 5,664 members between
them. Like those, I've set this one so new members are moderated. Post
once (maybe twice, I do have a life ;')) and I'll change you to
non-moderated. If you spot a spam link or file or photo, email me off
list and I'll remove it.

Turns out ElectronicDX just changed the names of all his groups,
adding "gcc" to the title. So it's gccloopantennas, etc. If you were a
member of his lists before, you are still a member. All the files and
links and archives are still intact over there.

However, that doesn't change anything I said above. I hope no one
leaves gccloopantennas for this one, but I do hope people join this
list in addition to that one. Post good links and files, please be
specific in your description. I reserve the right to delete a link or
file if there is no description, and I will probably make some folders
and move them around a bit as soon as there is enough to make that
worth doing.

Check my other lists to see what I do with files and links areas:






Thanks from the list-owner of the new loopantennas list.

Steve Greenfield aka Alien Steve aka Polymorph

I appreciate the thought, but please don't make me a moderator. I
am list-owner or moderator of 15 already!

I'm very happy that you did not delete any of your yahoogroups.

So what is GCC?

Steve

--- Adam Ebel <electronicdx@...> wrote:

Steve:

Heres the group:


You see, I needed to find a wonderful solution for my friend to
get more members in his group, so I had to change the name. its
still here. I'm not that dumb to delete hard
work, even my precious antenna designs. So for now the group is
open membership
and you can be my moderator to approve membership, Its for
something that used
to be an imaginary agency, now its more like for serious hobbyist
to enjoy for years
to come. Also I have messager so I am available to talk to you.
Believe me the
group needed security for those hard to do designs for copyright
violators. Take care.

__________________________________
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