John P

#33056

I have uploaded 2 new files to the group page a magnetic loop
antenna that I built to go with my BitX-40!?It's a 2 turn 4' loop for
40 meters.

One file contains the software for the tuning controller and the
other is a complete description of the project. The files can be
found in the folder: A 40 meter magnetic loop antenna .

Comments are, as always, appreciated!
--
John - WA2FZW

#33059

John, this looks really cool. Like yourself, I have a limited amount of real estate here to play with. I have the mfj mag loop, and even though it is only 3 feet across, single turn, I have had excellent success with it on 40. Looks lIke yours will be much more efficient.

I'll also put in a plug for Kitsandparts. I have ordered numerous boards from them over the years, and they worked well for a number of projects I have built. Unfortunately, they have really scaled back on the rf toolkit boards, as you can see from the number of items that are discontinued. I built a complete 6 band cw qrp rig using stuff mostly from them and N3ZI

Not sure why you couldn't get the swr bridge to work though...?

John P

#33060

On Mon, Oct 2, 2017 at 01:38 pm, Brent Seres wrote:

Not sure why you couldn't get the swr bridge to work though...?

It worked fine with a meter hooked to it, but for some reason,?it?just wouldn't work with the Arduino. I also have no clue why.
?
--
John - WA2FZW

Vince Vielhaber

#33065

Try a resistor to ground on the FWD and REF pins or on your arduino analog inputs.

Vince.

Show quoted text

On 10/02/2017 04:41 PM, John  P wrote:
On Mon, Oct 2, 2017 at 01:38 pm, Brent Seres wrote:

    Not sure why you couldn't get the swr bridge to work though...

It worked fine with a meter hooked to it, but for some reason, it just
wouldn't work with the Arduino. I also have no clue why.

--
John - WA2FZW

-- 
  Michigan VHF Corp.      
                          

John P

#33066

On Mon, Oct 2, 2017 at 02:49 pm, Vince Vielhaber wrote:

Try a resistor to ground on the FWD and REF pins or on your arduino analog inputs.

Did that. There are 100K resistors from the SWR bridge leads to ground. Didn't work with the? Kitsandparts bridge. Tried a bunch of different values.

?
--
John - WA2FZW

#33071

开云体育

Speaking of LOOPS!

I got this done (this far) last week!? It is 2 1/2' sections, so 20 ft. of 3/4" copper.? About 76" high?

The mounting for the Vac C is 1/8" copper plate, scrap off eBay.? Cap is 30-200pF and eBay too.

I used Cu. Unions, so I can take the Cap out and disassemble for moving it.? It comes apart in 20 seconds.

I am really surprised how well it receives sitting under the shed roof on the ground.

No, tuner yet?? A future project.? I am wondering now before it turns GREEN whether I should put clear spay paint on it?

About $200 so far.

Mike, WA6ISP

On 10/2/2017 12:50 PM, John P wrote:

I have uploaded 2 new files to the group page a magnetic loop
antenna that I built to go with my BitX-40!?It's a 2 turn 4' loop for
40 meters.

One file contains the software for the tuning controller and the
other is a complete description of the project. The files can be
found in the folder: A 40 meter magnetic loop antenna .

Comments are, as always, appreciated!
--
John - WA2FZW

-- 
Mike Hagen, WA6ISP
10917 Bryant Street
Yucaipa, Ca. 92399
(909) 918-0058
PayPal ID  "MotDog@..."
Mike@...

#33073

John I enjoyed the read. You did an amazing job building the antenna and controller.

John P

#33084

On Mon, Oct 2, 2017 at 03:29 pm, Michael Hagen wrote:

No, tuner yet?? A future project.? I am wondering now before it turns GREEN whether I should put clear spay paint on it?

Take a look at mine; It's pretty simple. And yes, I would clear-coat it. I always used clear Krylon on all my antennas.
?
--
John - WA2FZW

John P

#33085

On Mon, Oct 2, 2017 at 04:17 pm, RCC WB5YYM wrote:

John I enjoyed the read. You did an amazing job building the antenna and controller.

Thanks!
?
--
John - WA2FZW

#33095

Excellent write up. I've recently finished building an air variable cap and the next project is integrating the stepper and building a controller.?

Could you use relays to control your driver micro stepping with the Arduino? Also, you might want to look at the Sparkfun EasyDriver. It has logic pins broken out that can set the stepping from full to 1/8 and also an enable/disable pin. I also have a Chinese EasyDriver clone which was a fraction of the price of the original but I haven't tested either yet.?

Regards,

Paul
KG6QGE

John P

#33096

On Tue, Oct 3, 2017 at 02:40 am, <paul@...> wrote:

Could you use relays to control your driver micro stepping with the Arduino?

Thanks for the comments!

You could probably use relays, but they would have to operate really fast and operate a lot. I would suspect they would fail after a while. There's also the potential problem of contact bounce.

The EasyDriver looks like a great?one for? a loop tuner. I wish the one I'm using had the ability to program the step size on the fly. That would make it possible to do large moves of the capacitor?faster, then one could reduce the step size for fine tuning.

I'll be interested in hearing about your project.?Feel free to email at my callsign at?ARRL.org.
?
--
John - WA2FZW

Jack Purdum

#33101

I've used both the EasyDriver and this one from Polulu:

I found the Polulu to be a more robust driver.

Jack, W8TEE

Show quoted text

From: "paul@..." <paul@...>
To: [email protected]
Sent: Tuesday, October 3, 2017 5:40 AM
Subject: Re: [BITX20] Yet another magnetic loop antenna

Excellent write up. I've recently finished building an air variable cap and the next project is integrating the stepper and building a controller.?

Could you use relays to control your driver micro stepping with the Arduino? Also, you might want to look at the Sparkfun EasyDriver. It has logic pins broken out that can set the stepping from full to 1/8 and also an enable/disable pin. I also have a Chinese EasyDriver clone which was a fraction of the price of the original but I haven't tested either yet.?

Regards,

Paul
KG6QGE

Virus-free.

Vince Vielhaber

#33103

I found the Polulu to be the least dependable.  This is the one I use - I
bought the last ones from someone other than Banggood tho:

Vince.

Show quoted text

I've used both the EasyDriver and this one from Polulu:
DRV8825 Stepper Motor Driver (Header Pins Soldered)

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DRV8825 Stepper Motor Driver (Header Pins Soldered)
 Breakout board for DRV8825 stepper motor Six microstep resolutions (down
to 1/32-step) Continuous current per ...  |   |

  |

  |



I found the Polulu to be a more robust driver.
Jack, W8TEE


      From: "paul@..." <paul@...>
 To: [email protected]
 Sent: Tuesday, October 3, 2017 5:40 AM
 Subject: Re: [BITX20] Yet another magnetic loop antenna

Excellent write up. I've recently finished building an air variable cap
and the next project is integrating the stepper and building a
controller.??

Could you use relays to control your driver micro stepping with the
Arduino? Also, you might want to look at the Sparkfun EasyDriver. It has
logic pins broken out that can set the stepping from full to 1/8 and also
an enable/disable pin. I also have a Chinese EasyDriver clone which was a
fraction of the price of the original but I haven't tested either yet.??

Regards,

Paul
KG6QGE



|  | Virus-free. www.avast.com  |

-- 
   Michigan VHF Corp.      
               

#33106

开云体育

These Stepper Drivers are used a lot for 3D printers.? I got spares, but never have blow one up.

They are real inexpensive on eBay.

The is a lot bigger problem driving a Vacuum Variable on the Loop Ant than a Capacitor.

I am wondering how to come up with some "end stops" for turning the shaft.? They take about 18 or so turns end to end.

In fact mine feels like is is coming apart at the end in one direction, gets loose feeling.

And this stuff is near the RF field of the loop.? You sure don't want a bunch of metal stuff there.

Right now I just have to reach over and peak it for noise during receive since I have it near the BitX.

I turn the volume up and peak it.? I am going to put a piece of wood dowel on it temporarily.

Maybe it is not a real problem since if it stays tuned it never goes near the ends.

I am just worried about the stepper taking off and hitting the ends.

I wish it had a clutch arrangement built into it, but it feel like it is coming apart when I get near one end.

I have thought about a small belt to a 10 Turn pot, then it could be like a Servo and be driven to a pot position?

This is the first Vac Variable I have had in over 50 years of Hamming.? Its Cool!

Mike, WA6ISP

On 10/3/2017 6:24 AM, Jack Purdum via Groups.Io wrote:

I've used both the EasyDriver and this one from Polulu:

I found the Polulu to be a more robust driver.

Jack, W8TEE

From: "paul@..." <paul@...>
To: [email protected]
Sent: Tuesday, October 3, 2017 5:40 AM
Subject: Re: [BITX20] Yet another magnetic loop antenna

Excellent write up. I've recently finished building an air variable cap and the next project is integrating the stepper and building a controller.?

Could you use relays to control your driver micro stepping with the Arduino? Also, you might want to look at the Sparkfun EasyDriver. It has logic pins broken out that can set the stepping from full to 1/8 and also an enable/disable pin. I also have a Chinese EasyDriver clone which was a fraction of the price of the original but I haven't tested either yet.?

Regards,

Paul
KG6QGE

Virus-free.

-- 
Mike Hagen, WA6ISP
10917 Bryant Street
Yucaipa, Ca. 92399
(909) 918-0058
PayPal ID  "MotDog@..."
Mike@...

Jack Purdum

#33107

Mike:

Is there a way to track the number of turns the VVC has made and, when it reaches a certain count, it won't advance the stepper any further? It might get a little messy with micro-stepping, but it should be doable.

Jack, W8TEE

Show quoted text

From: Michael Hagen <motdog@...>
To: [email protected]
Sent: Tuesday, October 3, 2017 10:21 AM
Subject: Re: [BITX20] Yet another magnetic loop antenna