I'm thinking of building a version of this antenna for 17 meters.

http://www.infoark.org/InfoArk/Science-Engineering/Radio/Antennas/Gain%20Without\
%20Pain%20-%20A%20Beam%20Antenna%20for%20Field%20Day-Clarke_2001-06.pdf

I've never used coax phasing lines before, and since they are longer than the
distance between the elements, I was wondering about the best way to handle
them.  Should they be coiled somehow or left loosly looped over the support or
what? How do I keep symmetry?

My plan is to forego all the PVC supports shown and just have this as a
non-rotatable array suspended by lines on the top and guys at the bottom to hold
everything in position.

If anybody has the EZNEC (or MMANA) model for this, I'd love to have a copy to
play with!

73,
Bruce
WB8OGK

Hi All

I know variable caps aren't as easy to come by as they once were.
Is this usable or is the max cap a bit too low?

http://www.goldmine-elec-products.com/prodinfo.asp?number=G17992


Ken

>
>I know variable caps aren't as easy to come by as they once were.
>Is this usable or is the max cap a bit too low?
>
>http://www.goldmine-elec-products.com/prodinfo.asp?number=G17992
>

      Usable for fine-tuning high-Q circuitry.  At that price you could afford to
have a few just lying around.



Chris Trask
N7ZWY / WDX3HLB
Senior Member IEEE
http://www.home.earthlink.net/~christrask/

In my opinion I think that a 250-400 pf air variable
with spacing at around .25 inches is what's required,
anything else is try it and see........

van
wd8aam

At 15:03 6/5/2011, you wrote:
> >
> >I know variable caps aren't as easy to come by as they once were.
> >Is this usable or is the max cap a bit too low?
> >
> >http://www.goldmine-elec-products.com/prodinfo.asp?number=G17992
> >
>
>      Usable for fine-tuning high-Q circuitry.  At that price you
> could afford to have a few just lying around.
>
>
>
>Chris Trask
>N7ZWY / WDX3HLB
>Senior Member IEEE
>http://www.home.earthlink.net/~christrask/
>
>
>------------------------------------
>
>If you've got links, post them in the Links section!
>http://groups.yahoo.com/group/loopantennas/links
>
>Post files here. If the file comes from a website, please put it in
>the Links rather than uploading the file.
>http://groups.yahoo.com/group/loopantennas/files
>
>You can now view images at higher resolution in Photos. Upload JPG
>and GIF into Photos. Please convert BMP or TIF to JPG or GIF before uploading.
>http://ph.groups.yahoo.com/group/loopantennas/photos
>
>And please trim all this when replying!Yahoo! Groups Links
>
>
>

Hello to everybody,



I have put on my page a new article "Wideband Active Small Magnetic
Loop Antenna. Protection from Strong Electromagnetic Fields"
http://www.lz1aq.signacor.com/docs/Wide_Mag_loop_prot_v1/wideband_mag_lo\
op_protection.htm
<http://www.lz1aq.signacor.com/docs/Wide_Mag_loop_prot_v1/wideband_mag_l\
oop_protection.htm>





73,  Chavdar  LZ1AQ

www.lz1aq.signacor.com <http://www.lz1aq.signacor.com/>

Please email me at:    lz1aq@ abv.bg <mailto:lz1aq@...>



This message has been send to the following forums:

http://groups.yahoo.com/group/softrock40
<http://groups.yahoo.com/group/softrock40> /

http://groups.yahoo.com/group/soft_radio/
<http://groups.yahoo.com/group/soft_radio/>

http://groups.yahoo.com/group/Shortwave-SWL-Antenna
<http://groups.yahoo.com/group/Shortwave-SWL-Antenna> /

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<http://groups.yahoo.com/group/loopantennas> /

http://groups.yahoo.com/group/perseus_sdr/
<http://groups.yahoo.com/group/perseus_sdr/>



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

--- In loopantennas@yahoogroups.com, "bconner_01876" <bruce.conner@...> wrote:
>
> I'm thinking of building a version of this antenna for 17 meters.
>
>
http://www.infoark.org/InfoArk/Science-Engineering/Radio/Antennas/Gain%20Without\
%20Pain%20-%20A%20Beam%20Antenna%20for%20Field%20Day-Clarke_2001-06.pdf
>
> I've never used coax phasing lines before, and since they are longer than the
distance between the elements, I was wondering about the best way to handle
them.  Should they be coiled somehow or left loosly looped over the support or
what? How do I keep symmetry?
>
> My plan is to forego all the PVC supports shown and just have this as a
non-rotatable array suspended by lines on the top and guys at the bottom to hold
everything in position.
>
> If anybody has the EZNEC (or MMANA) model for this, I'd love to have a copy to
play with!
>
> 73,
> Bruce
> WB8OGK
>

hi Bruce,
Let 'em dangle if you want. They don't radiate nor receive.
A.

Hello folks,

I'm new to this group so please let me briefly introduce myself. I'm Daniele
Tincani from Livorno, Italy. I'm a SWL (with special interest for LF, MF and low
HF) and I like to homebrew simple projects like the one discussed in the
attached messages.
I would like to know if someone tried in practice to apply modifications
suggested by Chris to the amplfier circuit proposed by John 9V1VV. In particular
I would be interested in how to build the input BalBal and the output 1:1:1
BalUn and how connect the latter into the circuit.
Best regards
Daniele

--- In loopantennas@yahoogroups.com, Chris Trask <christrask@...> wrote:
>
> >
> >I would appreciate any comments you may have on this design;
> >
> >http://xephemera.blogspot.com/2009/08/16-30-mhz-broadband-low-noise-loop.html
> >
> >It is not an original - the circuit has been around for years.
> >
> >In my noisy urban and tropical environment I can detect no difference
> >when switching to my ALA 100L-1 amplifier.
> >
> >Some Finnish hams reported that the design was pretty good in quiet
> >environments compared with the Wellbrook.
> >
> >I now use both amps on separate loops orientated 90 degs  and switch
> >between the two.
> >
>
>      I've seen a number of amplifiers similar to that.  The first one that
comes to mind is that of the British fellow who has an extensive online
presentation of a large loop antenna.  Can't recall his name or the URL at the
moment, but I'm certain that there are list members who will readily recognize
who I'm refering to.
>
>      It would be interesting to compare the radiation patterns that result
between high input impedance and low input impedance amplifiers used for
wideband active loop antenna applications.  I suspect that the former approach
would deteriorate the null.
>
>      One item I find missing from this design is an input BalBal transformer. 
Such a transformer would serve a number of uses, in particular providing a
degree of immunity from common-mode interference such as lightning strikes.  It
would also provide a ground reference for the antenna proper, and in addition
would allow the two transistors to have an identical base voltage.  The limiting
diodes would be placed across the primary side of the transformer.
>
>      I would also disconnect the two emitters, have a separate biasing
resistor from each emitter to ground, and then a suitable capacitor between the
two emitters.  Then the two capacitors from the collectors to the output
transformer primary winding can be eliminated.  The 1:1 UnUn output transformer
could be replaced with a 1:1:1 BalUn, the centre tap of the primary connected to
the supply line.  This would increase the P1dB a bit plus raise the gain by an
additional 6dB.
>
> Chris
>

Hello all,

I'm planning to build a wideband active loop antenna for reception, hopefully
covering LF to low HF.
Now I'm thinking about how to build the aerial element.
Due to space restrictions, I'm forced to no more than 80 cm diameter. Is this
enough for an acceptable antenna efficiency, in principle?
Second questions (very classic!) is: shielded or unshielded?
Third question is: how better is copper tubing - for practical use - in
comparison with large-diameter coax cable (or other solutions), in both the
shielded and the unshielded cases?
Many thanks in advance for your feedbacks.
Best regards
Daniele

Hi Daniele,

I'm using a 2' (60cm) tuned loop for MW and one about 40cm for SW up to
60M. I haven't built anything under a Meter for LW but I don't see why
it couldn't be done.

Tim

On 6/13/2011 4:57, Daniele wrote:
>
>
> Hello all,
>
> I'm planning to build a wideband active loop antenna for reception,
> hopefully covering LF to low HF.
> Now I'm thinking about how to build the aerial element.
> Due to space restrictions, I'm forced to no more than 80 cm diameter.
> Is this enough for an acceptable antenna efficiency, in principle?
> Second questions (very classic!) is: shielded or unshielded?
> Third question is: how better is copper tubing - for practical use -
> in comparison with large-diameter coax cable (or other solutions), in
> both the shielded and the unshielded cases?
> Many thanks in advance for your feedbacks.
> Best regards
> Daniele
>



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

Could anyone recommend a good antenna for receiving 1570khz on the am
radio? I would be interested in either a store bought or a schematic for one.
                                           Thanks,
                                           Hubert

Use the same one you use for 1480 or 1620.  What is so unique about 1570 for
you.

--- On Mon, 6/13/11, Hubert Badgley <habadgley@...> wrote:

From: Hubert Badgley <habadgley@...>
Subject: [loopantennas] am antenna
To: loopantennas@yahoogroups.com
Date: Monday, June 13, 2011, 9:42 AM
















 









              Could anyone recommend a good antenna for receiving 1570khz on the
am radio? I would be interested in either a store bought or a schematic for one.

                                           Thanks,

                                           Hubert



























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

How far is this station on 1570KHz from your location? What are your
requirements for size and or form factor of this antenna?
Your mileage will vary but there has been a recent thread about small loops such
as the Terk Advantage or the Kaito AN-200 (and derivatives). These are small
(9") loop antennas which are tunable across the entire AM band. I have also
built similar type antennas with a loopstick antenna and tuning capacitor, when
one could buy loopstick antennas for AM radios. I have even done this using the
coil and capacitor for (Quaker) Oatbox crystal radios. These loops are designed
to passively couple to your existing radio and are meant for indoor use.
 A nice feature of the Terk is that there is a 1/8" jack on the back that can be
coupled to a wire antenna and ground connection should that be needed. One could
also throw wire out the window and wrap the free end around the radio to achieve
the same goal. I prefer using the Terk to couple the antenna as it allows a bit
more tuning of the antenna coupling to the radio.
73,kevinkc6pob




Could anyone recommend a good antenna for receiving 1570khz on the am radio? I
would be interested in either a store bought or a schematic for one.





















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

Here is a link for the Terk Advantage. I am not trying to promote it. I just
have one and am familiar with it. It's not perfect but adds to my listening
pleasure at home or on travel (yes, it has gone in my checked luggage without
problem).http://www.ccrane.com/instruction-manuals/terk-am-advantage.pdf

73,kevinkc6pob
--- On Mon, 6/13/11, kevin asato <kc6pob@...> wrote:

From: kevin asato <kc6pob@...>
Subject: Re: [loopantennas] am antenna
To: loopantennas@yahoogroups.com
Date: Monday, June 13, 2011, 11:31 PM
















 









       How far is this station on 1570KHz from your location? What are your
requirements for size and or form factor of this antenna?

Your mileage will vary but there has been a recent thread about small loops such
as the Terk Advantage or the Kaito AN-200 (and derivatives). These are small
(9") loop antennas which are tunable across the entire AM band. I have also
built similar type antennas with a loopstick antenna and tuning capacitor, when
one could buy loopstick antennas for AM radios. I have even done this using the
coil and capacitor for (Quaker) Oatbox crystal radios. These loops are designed
to passively couple to your existing radio and are meant for indoor use.

 A nice feature of the Terk is that there is a 1/8" jack on the back that can
be coupled to a wire antenna and ground connection should that be needed. One
could also throw wire out the window and wrap the free end around the radio to
achieve the same goal. I prefer using the Terk to couple the antenna as it
allows a bit more tuning of the antenna coupling to the radio.

73,kevinkc6pob



Could anyone recommend a good antenna for receiving 1570khz on the am radio? I
would be interested in either a store bought or a schematic for one.



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



























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

Nothing unusal just a channel which is about 15 miles away with a weak
transmitter. It has some programs I would like to pickup.

--- In loopantennas@yahoogroups.com, Tom Humes <tomhumes3050@...> wrote:
>
> Use the same one you use for 1480 or 1620.  What is so unique about 1570 for
you.
>
> --- On Mon, 6/13/11, Hubert Badgley <habadgley@...> wrote:
>
> From: Hubert Badgley <habadgley@...>
> Subject: [loopantennas] am antenna
> To: loopantennas@yahoogroups.com
> Date: Monday, June 13, 2011, 9:42 AM
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>  
>
>
>
>
>
>
>
>
>
>              Could anyone recommend a good antenna for receiving 1570khz on
the am radio? I would be interested in either a store bought or a schematic for
one.
>
>                                           Thanks,
>
>                                           Hubert
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
> [Non-text portions of this message have been removed]
>

Thanks for the information. I am about 15 miles from this weak station. If
I try the wire out the window and wrapped around the receiver and get no results
will these antennas you mention be worth trying or should I put something up in
the air outside.
                                                    Thanks

--- In loopantennas@yahoogroups.com, kevin asato <kc6pob@...> wrote:
>
> How far is this station on 1570KHz from your location? What are your
requirements for size and or form factor of this antenna?
> Your mileage will vary but there has been a recent thread about small loops
such as the Terk Advantage or the Kaito AN-200 (and derivatives). These are
small (9") loop antennas which are tunable across the entire AM band. I have
also built similar type antennas with a loopstick antenna and tuning capacitor,
when one could buy loopstick antennas for AM radios. I have even done this using
the coil and capacitor for (Quaker) Oatbox crystal radios. These loops are
designed to passively couple to your existing radio and are meant for indoor
use.
>  A nice feature of the Terk is that there is a 1/8" jack on the back that can
be coupled to a wire antenna and ground connection should that be needed. One
could also throw wire out the window and wrap the free end around the radio to
achieve the same goal. I prefer using the Terk to couple the antenna as it
allows a bit more tuning of the antenna coupling to the radio.
> 73,kevinkc6pob
>
>
>
>
> Could anyone recommend a good antenna for receiving 1570khz on the am radio? I
would be interested in either a store bought or a schematic for one.
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
> [Non-text portions of this message have been removed]
>

I have some low power community broadcasts (emergency, traffic) that I dig out
with my Terk. Two are around 1620-1630KHz and another at LAX (about 12 miles
distant) at 530KHz that need a bit of help at times - too much computer and
other electrical trash in my house!
Good luck,kevinkc6pob
--- On Tue, 6/14/11, Hubert Badgley <habadgley@...> wrote:

From: Hubert Badgley <habadgley@...>
Subject: [loopantennas] Re: am antenna
To: loopantennas@yahoogroups.com
Date: Tuesday, June 14, 2011, 6:52 AM
















 













Thanks for the information. I am about 15 miles from this weak station. If I try
the wire out the window and wrapped around the receiver and get no results will
these antennas you mention be worth trying or should I put something up in the
air outside.

                                                    Thanks



--- In loopantennas@yahoogroups.com, kevin asato <kc6pob@...> wrote:

>

> How far is this station on 1570KHz from your location? What are your
requirements for size and or form factor of this antenna?

> Your mileage will vary but there has been a recent thread about small loops
such as the Terk Advantage or the Kaito AN-200 (and derivatives). These are
small (9") loop antennas which are tunable across the entire AM band. I have
also built similar type antennas with a loopstick antenna and tuning capacitor,
when one could buy loopstick antennas for AM radios. I have even done this using
the coil and capacitor for (Quaker) Oatbox crystal radios. These loops are
designed to passively couple to your existing radio and are meant for indoor
use.

>  A nice feature of the Terk is that there is a 1/8" jack on the back that can
be coupled to a wire antenna and ground connection should that be needed. One
could also throw wire out the window and wrap the free end around the radio to
achieve the same goal. I prefer using the Terk to couple the antenna as it
allows a bit more tuning of the antenna coupling to the radio.

> 73,kevinkc6pob

>

>

>

>

> Could anyone recommend a good antenna for receiving 1570khz on the am radio? I
would be interested in either a store bought or a schematic for one.

>

>

>

>

>

>

>

>

>

>

>

>

>

>

>

>

>

>

>

>

>

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

>



























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

I need some help in deciding what size stepper motor for my loop, I have a 1.8
deg. motor but it's not tight enough. What is a good stepper motor to tune a
maganetic loop?

73 de Peter

Hello peter

I presume that when you say that a 1.8 degree stepping motor is not tight
enough, you mean that it does not have sufficient resolution?

Most hybrid stepping motors have a step size of 1.8 degress.  In other
types, the step size is typically larger.  With the hybrid motor, you have a
coiuple of options:
i)  use a gear box to improve the resolution
ii)  use a microstepping drive, to move the motor a small fraction of a
step.

HTH and 73

John  KC0G


In a message dated 6/15/2011 8:59:16 PM Central Daylight Time,
ve3pcd@... writes:
> I need some help in deciding what size stepper motor for my loop, I have
> a 1.8 deg. motor but it's not tight enough. What is a good stepper motor to
> tune a maganetic loop?
>
> 73 de Peter


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

Hi John,

  What I meant is that it does not allow me to make very fine adjustments. I have
a controller, are you saying that I will need a gearbox as well, and what ratio
do you recommend?

Also, would the 1.8 deg stepper be ok with a gearbox?

73 de Peter


--- In loopantennas@yahoogroups.com, crabtreejr@... wrote:
>
> Hello peter
>
> I presume that when you say that a 1.8 degree stepping motor is not tight
> enough, you mean that it does not have sufficient resolution?
>
> Most hybrid stepping motors have a step size of 1.8 degress.  In other
> types, the step size is typically larger.  With the hybrid motor, you have a
> coiuple of options:
> i)  use a gear box to improve the resolution
> ii)  use a microstepping drive, to move the motor a small fraction of a
> step.
>
> HTH and 73
>
> John  KC0G
>
>
> In a message dated 6/15/2011 8:59:16 PM Central Daylight Time,
> ve3pcd@... writes:
> > I need some help in deciding what size stepper motor for my loop, I have
> > a 1.8 deg. motor but it's not tight enough. What is a good stepper motor to
> > tune a maganetic loop?
> >
> > 73 de Peter
>
>
> [Non-text portions of this message have been removed]
>

de Peter,

There are 6:1 reduction drives available on Ebay and elsewhere with 1/4"
(6mm) shafts in and out that would give you 540 steps over 180* or 0.3*
per step.
Look under Ham radio/parts.

Tim

On 6/16/2011 10:22, ve3pcd wrote:
>
> Hi John,
>
> What I meant is that it does not allow me to make very fine
> adjustments. I have a controller, are you saying that I will need a
> gearbox as well, and what ratio do you recommend?
>
> Also, would the 1.8 deg stepper be ok with a gearbox?
>
> 73 de Peter
>
> --- In loopantennas@yahoogroups.com
> <mailto:loopantennas%40yahoogroups.com>, crabtreejr@... wrote:
> >
> > Hello peter
> >
> > I presume that when you say that a 1.8 degree stepping motor is not
> tight
> > enough, you mean that it does not have sufficient resolution?
> >
> > Most hybrid stepping motors have a step size of 1.8 degress. In other
> > types, the step size is typically larger. With the hybrid motor, you
> have a
> > coiuple of options:
> > i) use a gear box to improve the resolution
> > ii) use a microstepping drive, to move the motor a small fraction of a
> > step.
> >
> > HTH and 73
> >
> > John KC0G
> >
> >
> > In a message dated 6/15/2011 8:59:16 PM Central Daylight Time,
> > ve3pcd@... writes:
> > > I need some help in deciding what size stepper motor for my loop,
> I have
> > > a 1.8 deg. motor but it's not tight enough. What is a good stepper
> motor to
> > > tune a maganetic loop?
> > >
> > > 73 de Peter
> >
> >
>



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

Hi Tim,

  Could I also use a DC motor with a variable power controller, or may be a gear
motor? All I need is to make very fine adjustments.

Peter


--- In loopantennas@yahoogroups.com, Tim Hills <thills@...> wrote:
>
> de Peter,
>
> There are 6:1 reduction drives available on Ebay and elsewhere with 1/4"
> (6mm) shafts in and out that would give you 540 steps over 180* or 0.3*
> per step.
> Look under Ham radio/parts.
>
> Tim
>
> On 6/16/2011 10:22, ve3pcd wrote:
> >
> > Hi John,
> >
> > What I meant is that it does not allow me to make very fine
> > adjustments. I have a controller, are you saying that I will need a
> > gearbox as well, and what ratio do you recommend?
> >
> > Also, would the 1.8 deg stepper be ok with a gearbox?
> >
> > 73 de Peter
> >
> > --- In loopantennas@yahoogroups.com
> > <mailto:loopantennas%40yahoogroups.com>, crabtreejr@ wrote:
> > >
> > > Hello peter
> > >
> > > I presume that when you say that a 1.8 degree stepping motor is not
> > tight
> > > enough, you mean that it does not have sufficient resolution?
> > >
> > > Most hybrid stepping motors have a step size of 1.8 degress. In other
> > > types, the step size is typically larger. With the hybrid motor, you
> > have a
> > > coiuple of options:
> > > i) use a gear box to improve the resolution
> > > ii) use a microstepping drive, to move the motor a small fraction of a
> > > step.
> > >
> > > HTH and 73
> > >
> > > John KC0G
> > >
> > >
> > > In a message dated 6/15/2011 8:59:16 PM Central Daylight Time,
> > > ve3pcd@ writes:
> > > > I need some help in deciding what size stepper motor for my loop,
> > I have
> > > > a 1.8 deg. motor but it's not tight enough. What is a good stepper
> > motor to
> > > > tune a maganetic loop?
> > > >
> > > > 73 de Peter
> > >
> > >
> >
>
>
>
> [Non-text portions of this message have been removed]
>

I am looking for a project  MW  pasive loop no more of 10 " hight .

Ibuilted some thing like MTM  am loop ,it works very good  but it is too
hight  17 " and it is dificult to operate in a small computer (3 level)
table.

I will apreciated if somebody help in a project.

Thanks  Jose Mendicoa  Valencia Venezuela  jmmendicoa@...
<mailto:jmmendicoa@...>



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

The Grundig AN-200 tuned loop runs 25-30$ US on evil-bay, etc. It peaks at ~10
3/16". The rear foot could be cut to lower it to 10". It is quite well made and
has a 1/8" jack on the back foot for connection to your receiver - or it can
magnetically couple to a portable.

John

--- In loopantennas@yahoogroups.com, "jose maria" <jmmendicoa@...> wrote:
>
>
> I am looking for a project  MW  pasive loop no more of 10 " hight .
>
> Ibuilted some thing like MTM  am loop ,it works very good  but it is too
> hight  17 " and it is dificult to operate in a small computer (3 level)
> table.
>
> I will apreciated if somebody help in a project.
>
> Thanks  Jose Mendicoa  Valencia Venezuela  jmmendicoa@...
> <mailto:jmmendicoa@...>
>
>
>
> [Non-text portions of this message have been removed]
>

Thanks John for the sugestion i order from Amazon the an-200 but they are
sending me the the an-100 (Brands Kaito,Grundig or Tecsun )they are all the same
,i prefer this design because the tunning Knob is in one side of the antenna
,not in the middle. Thanks   Jose

--- In loopantennas@yahoogroups.com, "John" <JRTOW3RD@...> wrote:
>
> The Grundig AN-200 tuned loop runs 25-30$ US on evil-bay, etc. It peaks at ~10
3/16". The rear foot could be cut to lower it to 10". It is quite well made and
has a 1/8" jack on the back foot for connection to your receiver - or it can
magnetically couple to a portable.
>
> John
>
> --- In loopantennas@yahoogroups.com, "jose maria" <jmmendicoa@> wrote:
> >
> >
> > I am looking for a project  MW  pasive loop no more of 10 " hight .
> >
> > Ibuilted some thing like MTM  am loop ,it works very good  but it is too
> > hight  17 " and it is dificult to operate in a small computer (3 level)
> > table.
> >
> > I will apreciated if somebody help in a project.
> >
> > Thanks  Jose Mendicoa  Valencia Venezuela  jmmendicoa@
> > <mailto:jmmendicoa@>
> >
> >
> >
> > [Non-text portions of this message have been removed]
> >
>

Hi, all.
Loop rookie here.
On a magnetic loop, I read about fairly extreme measures to keep any unnecessary
resistance out of the loop - silver solder rather than lead or tin, 3/4" pipe or
larger rather than 1/2", etc.  In considering capacitor types, motorized. Vacuum
variables seem to rise to the top, and butterfly capacitors are right behind
them.  But, when I look at them, I see rather small connection points, wires or
screws, which seems to conflict with the effort described above.  Is there
something I'm missing? Is it a big deal?

Bill, WWoJ
MN

Vacuum Variables are sort of a catch 22 when it  comes to
transmitting loops. All the information says to never use  screw-on
or bolted connections. Vacuum variables are very low  loss
but the only way you can make a
connection to a vacuum  variable is with a bolt or screw or
some type of clamp. The best way to try  to cope is to
use silver-on-silver connections and firmly clamp a  silver
strap as tight as possible around the vacuum variable, which
should  be silver plated on the outside of the body where
connections are  made.

One way around this is to build your own trombone-style
variable  capacitor using copper tubes and Teflon sheet for
insulation. This way you  can integrate the trombone capacitor
directly into the loop antenna and  silver solder all connections.

Also never use wire or "flying leads" when  connecting any kind
of capacitor to a transmitting loop. Use only copper  strap at least one
inch
wide when making any type of connection to a  transmitting loop. Do
not use flexible ground braid when making connections,  it is too lossy.

73 - Todd WD4NGG

I found the following announcement on a hamradio site. Even if you
don't read french it may be of value for you. It is not a book but a  well
organised collection of pdf files. Thes are well illustrated with
schematicvs, drawings and pictures.

regards,

Cor Beijersbergen





The Big 'French Handbook' - free to download


New 2011 edition - available since June 25 2011.

Now, it is possible to download free the 'French Handbook' accomplished by
F6BCU.

Numerous technical articles are at your disposal, ideal for home-brew.

You can download compact disk free on the site of Onlineradio (exclusive).
http://communaute.onlineradio.fr/files/file/
<http://communaute.onlineradio.fr/files/file/162-handbook-de-la-ligne-bleue/
>
162-handbook-de-la-ligne-bleue/ - for download (540 Mo)

Jean-Nicolas
http://www.onlineradio.fr <http://www.onlineradio.fr/>



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

Hello Chris and group,

After trying several options (gain, bandwidth, stability - pick any two :) ) ,
I've decided to build the amplifier described in your article
WidebandLoopAntennaAmplifierRevA.pdf.
The problem is I don't have the binocular cores made of 61 material, only made
of 43 material. I understand this will kill the performance of T3, because it is
loaded with the very low input impedance of the second stage.
Question 1: Can 43 material still be used for T6? Its loading impedance is 50
Ohm.
Question 2: If I omit T3 altogether and couple the stages directly (with the
necessary bias circuit modifications), how much gain would I lose? My naive
opinion is that in the end, voltage gain of the whole amplifier is the ratio of
50 Ohm to the input impedance. I don't see how interstage and output
transformers can increase it. T6 is still nice to have for balanced to
unbalanced connection and for splitting/combining the power and the signal.

73, Mike

Thank you for the information. A very nice site.
Dr Don HC4/W4BWS

   ----- Original Message -----
   From: dx11
   To: Shortwave-SWL-Antenna@yahoogroups.com ; loopantennas@yahoogroups.com ;
qrp-tech@yahoogroups.com
   Sent: Sunday, June 26, 2011 10:14 AM
   Subject: [loopantennas] OT (a bit), a french book freely available





   I found the following announcement on a hamradio site. Even if you
   don't read french it may be of value for you. It is not a book but a well
   organised collection of pdf files. Thes are well illustrated with
   schematicvs, drawings and pictures.

   regards,

   Cor Beijersbergen




   The Big 'French Handbook' - free to download

   New 2011 edition - available since June 25 2011.

   Now, it is possible to download free the 'French Handbook' accomplished by
   F6BCU.

   Numerous technical articles are at your disposal, ideal for home-brew.

   You can download compact disk free on the site of Onlineradio (exclusive).
   http://communaute.onlineradio.fr/files/file/
   <http://communaute.onlineradio.fr/files/file/162-handbook-de-la-ligne-bleue/
   >
   162-handbook-de-la-ligne-bleue/ - for download (540 Mo)

   Jean-Nicolas
   http://www.onlineradio.fr <http://www.onlineradio.fr/>

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





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