Forums :: NEW! Web Resources :: Features :: Photo Gallery :: Vintage Radio Shows :: Archives
Support This Site: Contributors :: Advertise


It is currently Oct Sat 24, 2020 3:35 am


All times are UTC [ DST ]





Post New Topic Post Reply  [ 85 posts ]  Go to page Previous  1, 2, 3, 4, 5  Next
Author Message
 Post subject: Re: COAX lead-in for BCB longwire antenna?
PostPosted: Oct Mon 21, 2013 11:40 pm 
Member
User avatar

Joined: Jan Mon 18, 2010 2:13 am
Posts: 21285
Location: Dayton Ohio
I built this outdoor loop antenna to help me bring in CFZM AM740 out of Toronto. It does a VERY good job at that!

Though, Tulsa often interferes, which is in the same plane.... CURSES!
Though, by the time darkness falls, Tulsa drops its power and AM740 rolls in unimpeded :D

-Steve


Attachments:
outdoorloop1.jpg
outdoorloop1.jpg [ 55.02 KiB | Viewed 3962 times ]

_________________
Radio Interests
-Zenith
-Sparton
-Pre-War FM
Consoles and floor models, the bigger, the better!
Top
 Profile  
 
 Post subject: Re: COAX lead-in for BCB longwire antenna?
PostPosted: Oct Mon 21, 2013 11:52 pm 
Member
User avatar

Joined: Jan Thu 01, 1970 1:00 am
Posts: 36198
Location: SoCal, 91387
I think there was a thread where you gave the particulars of your loop; would you have the addy for it?

_________________
\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\He Who Dies With The Most Radios Wins/////////////////////////


Top
 Profile  
 
 Post subject: Re: COAX lead-in for BCB longwire antenna?
PostPosted: Oct Tue 22, 2013 12:21 am 
Member
User avatar

Joined: Jan Mon 18, 2010 2:13 am
Posts: 21285
Location: Dayton Ohio
I can only find this post...

viewtopic.php?f=12&t=208459

Here are details from an e-mail I sent. I cannot seem to find the actual files...

-------------------------------------------------
Here are a few drawings for the loop antenna I built.

The stepper motor came out of an old junk Seagate hard drive from the 1980s. My design works with 4 wire stepper motors requiring an "H" bridge driver circuit.

As the optical encoder puts out two square wave signals 90 degrees out of phase with each other, it works well for driving the stepper motor.

The wire I used on the loop is from a 100 foot long (30 meter long) extension cord which I stripped apart. An inexpensive way to find wire.

There is a relay inside the box which I was going to use to switch a tap in the loop, but I decided not to use it.

The "Link" turn is actually the innermost turn on the loop, though it probably doesn't make any difference where it is.

-Steve


Attachments:
antennacontroller1.gif
antennacontroller1.gif [ 11.84 KiB | Viewed 3951 times ]
loopandbox.jpg
loopandbox.jpg [ 35.17 KiB | Viewed 3951 times ]
loopantenna2.gif
loopantenna2.gif [ 7.38 KiB | Viewed 3951 times ]
outdoor-loop-tuner.jpg
outdoor-loop-tuner.jpg [ 64.38 KiB | Viewed 3951 times ]
outdoor-loop-rebuilt.jpg
outdoor-loop-rebuilt.jpg [ 43.71 KiB | Viewed 3951 times ]

_________________
Radio Interests
-Zenith
-Sparton
-Pre-War FM
Consoles and floor models, the bigger, the better!
Top
 Profile  
 
 Post subject: Re: COAX lead-in for BCB longwire antenna?
PostPosted: Oct Tue 22, 2013 2:38 am 
Member
User avatar

Joined: Jan Thu 01, 1970 1:00 am
Posts: 2234
Location: Virginia Beach Va
Steve that is impressive !
Thanks for posting.


Last edited by davep on Oct Tue 22, 2013 4:34 am, edited 1 time in total.

Top
 Profile  
 
 Post subject: Re: COAX lead-in for BCB longwire antenna?
PostPosted: Oct Tue 22, 2013 4:30 am 
Moderator
User avatar

Joined: Jan Thu 01, 1970 1:00 am
Posts: 21951
Location: Somers, CT
Nice!!!! I love it!

_________________
Just because it can be done doesn't mean it should be done.


Top
 Profile  
 
 Post subject: Re: COAX lead-in for BCB longwire antenna?
PostPosted: Oct Tue 22, 2013 5:03 am 
Member
User avatar

Joined: Jan Thu 01, 1970 1:00 am
Posts: 31285
Location: Maryland 20709, USA
azenithnut wrote:
Here are a few drawings for the loop antenna I built.
Beautiful job, Steve, and excellent documentation.

- Leigh

_________________
73 de W3NLB
http://www.AtwaterKent.info
Click "Grebe Stuff" for Synchrophase info


Top
 Profile  
 
 Post subject: Re: COAX lead-in for BCB longwire antenna?
PostPosted: Oct Tue 22, 2013 10:53 am 
Member

Joined: Mar Tue 27, 2012 1:24 pm
Posts: 1229
fifties wrote:
before the North Las Vegas station was on the air, I had been able to receive WHAS, Louisville, Ky (my farthest east AM DX). In researching, apparently KXNT broadcasts with 25,000 watts at night, and they are due east of me.

It appears that there is an oldies station in Seaside, Oregon, KSWB, at 840 KC also, but they only broadcast with 500 watts.

That leaves KMPH in Modesto as the target, as their format is, "Graffiti Gold Oldies", broadcasting with 5,000 watts, and located north of me, so I might get away with a loop, positioned to null out the eastward broadcasting.
Renton481 wrote:
Just wind 16-25 windings of wire around a milk crate, clip the ends to the tuner cap. Cut the windings to fit the khz range you want. I started out with about 24 windings, and ended up with 16 to fit 520-1700 khz.

Solid or stranded, bare or insulated (or does that matter) and what gauge do you suggest using?


Hi Fifties,
I don't know the gauge of the wire I used (not that savvy about wire gauges yet). It's a little bit bigger than regular radio hookup wire, and it's stranded -- about the size of speaker wire, or zip cord wire. Measuring the width of just the stranded wire, it's about a millimeter wide, maybe a little less. I would use whatever wire you've got, as long as it's somewhere around the size of hookup wire, or stranded speaker wire (stripped in half). You may have to use a few more windings than 16-25, or a few less. The plans I used called for roughly 25 turns of stranded wire, spaced 3/8 inch apart. I just wound 25 turns, and just spaced the windings a more than a wire-width, and left it at that. I ended up taking off a few windings to get the loop to tune to 1700 khz. At first it tuned from below 510 to just below 1600. Now it tunes from 510 to 1700.

The windings on my box crate loop aren't glued or secured to the crate, although I may try to eventually secure them that way. Once, after storing it away for a while, the windings on the loop got a bit bunched up, and when I started using it again, the tuning range seemed a bit reduced, to where the loop wouldn't tune past 1600. I spaced the windings back out again and it tuned into the X band again, about to 1650 or so. I then removed a couple windings and got it to tune from 510 to 1700 (I don't know if it's exactly peaking at 1700, but it does boost 1700 well enough for me right now).

I use zip ties to secure the tuner to the crate, and alligator clips to connect the ends of the loop to the tuner. I also have electrical tape securing the the wires at each end of the loop to the crate itself, to keep the winding taut. I may eventually make it more secure, but right now I'm still experimenting.

Tonight I just finished putting together a four crate loop (11-12 turns of the same gauge stranded wire, all four milk crates secured together with zip ties). So far it works well, but I haven't used it enough to see what she'll really do. She definitely is louder than the Select-A-Tenna. Not sure how it compares to the single crate loop yet.

I live in the NW, in WA state. Here on 840 I get two oldies stations from Oregon, KSWB Seaside and KKNX Eugene. They both play a good mix of oldies. Usually, I hear both of them at the same time, sometimes with KXNT Las Vegas in the mix, usually waaaay in the background.

Like you, I logged WHAS before the clears began to be populated with new stations. I've never heard it since the early 1980s -- when I managed to get it on my boombox + a 4 ft spiral loop I used to have.

Chris


Top
 Profile  
 
 Post subject: Re: COAX lead-in for BCB longwire antenna?
PostPosted: Oct Tue 22, 2013 10:58 am 
Member

Joined: Mar Tue 27, 2012 1:24 pm
Posts: 1229
Nice job on the outdoor loop antenna, Steve -- very impressive!

What's the best DX you've gotten with that one?

Chris


Top
 Profile  
 
 Post subject: Re: COAX lead-in for BCB longwire antenna?
PostPosted: Oct Tue 22, 2013 5:13 pm 
Member
User avatar

Joined: Jan Mon 18, 2010 2:13 am
Posts: 21285
Location: Dayton Ohio
Thanks everyone. It was a fun project!

When I started working out the remote motor controlled variable capacitor, I was talking with a friend here at work about it. I showed him a stepper motor I had out of an old Seagate hard drive and he quickly gave me the H bridge circuit needed to drive it, but he thought I should drive it with a microcontroller.

Seeing all it needed was a pair of square wave signals in Quadrature, I came up with the idea of using a rotary encoder. Keep things simple, is my motto :wink:

It works great! though i do have quite a bit of RF interference as I tune the antenna. of course all power is removed once the knob is released, so its fine after the peak is found.

I have not DXed with it yet. My main aim was to get AM740 clearly and it does exactly that!

I will see what i can do with it this winter when I have time to tune around the band and rotate the antenna.

-Steve

_________________
Radio Interests
-Zenith
-Sparton
-Pre-War FM
Consoles and floor models, the bigger, the better!


Top
 Profile  
 
 Post subject: Re: COAX lead-in for BCB longwire antenna?
PostPosted: Oct Tue 22, 2013 6:06 pm 
Member
User avatar

Joined: Jan Thu 01, 1970 1:00 am
Posts: 2234
Location: Virginia Beach Va
Steve, come up with a hack that converts that uA or voltage reading
to a digital frequency readout!
A few questions ..does the motor / optical setup for the cap resolve
to a few pF? What kind of human interface control do you have inside?
(Not familiar with this.)


Top
 Profile  
 
 Post subject: Re: COAX lead-in for BCB longwire antenna?
PostPosted: Nov Fri 01, 2013 9:52 pm 
Member
User avatar

Joined: Jan Thu 01, 1970 1:00 am
Posts: 36198
Location: SoCal, 91387
In order to begin construction of an indoor loop antenna, I ordered two 23" diameter x 3/4" wide wood quilting hoops online, and got a pretty good price;

http://www.joann.com/wood-quilt-hoop-23 ... 11016.html

They even had a special shipping price of 31 cents, but it was just good until the end of October.

I plan to use wood glue to attach the two hoops together, so I'll have a 1-1/2 inch width, in order to wind the coil around.

Now here's a question;

rather than having this tuneable, by using a variable tuning cap, would it work inductively either just by itself, or with a fixed capacitor of a certain value connected between it's two wire ends, and cover the BCB?

Or is a tuning cap required in order for it to work at all?

_________________
\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\He Who Dies With The Most Radios Wins/////////////////////////


Top
 Profile  
 
 Post subject: Re: COAX lead-in for BCB longwire antenna?
PostPosted: Nov Fri 01, 2013 10:11 pm 
Member
User avatar

Joined: Jan Mon 18, 2010 2:13 am
Posts: 21285
Location: Dayton Ohio
It will need to be tuned. A loop by itself won't do much.

If the radio your going to use has a ferrite rod antenna inside, simply bringing your loop within a foot of the radio will make a dramatic difference!

I have not tried this, but somewhere on the web, I saw a design using computer ribbon cable to make a portable collapsible loop.
No winding necessary as all the work is at the end connecting the wires together. Just shift over one wire and solder them all together, you have a coil.

-Steve

_________________
Radio Interests
-Zenith
-Sparton
-Pre-War FM
Consoles and floor models, the bigger, the better!


Top
 Profile  
 
 Post subject: Re: COAX lead-in for BCB longwire antenna?
PostPosted: Nov Fri 01, 2013 10:13 pm 
Member
User avatar

Joined: Jun Wed 14, 2006 11:49 pm
Posts: 7141
Location: Leo, IN or Zellwood, FL
fifties wrote:

Or is a tuning cap required in order for it to work at all?


The short answer is YES the Tuning Capacitor is required. The Tuned Loops are very sharp in their tuning. If you have it adjusted correctly for a BCB station and then tune to another station 20-30 Khz away you will want to retune the loop capacitor.

So 30 years ago I had a nice tuned loop that was about 50 feet away from the house. I found some 12 volt dc motor with a gearbox on it that came down to around 3 or 4 turns per minute. Coupled that to a variable capacitor that didn't have any stops on it. It would just continue to go round and round. So tune in a station... hit momentary pushbutton switch that operated the motor until you hit the sweet spot. If you passed it up just go around again until you hit it again. Also had a rotor on the loop so it could be turned to null out unwanted stations. That of course was many years ahead of the device that Steve came up with to position his tuning capacitor.

John k9uwa

_________________
http://www.JohnJeanAntiqueRadio.com


Top
 Profile  
 
 Post subject: Re: COAX lead-in for BCB longwire antenna?
PostPosted: Nov Fri 01, 2013 10:35 pm 
Member
User avatar

Joined: Jan Mon 18, 2010 2:13 am
Posts: 21285
Location: Dayton Ohio
John, your idea with a motor and continuous turn variable cap is so simple, its Genius! :D

I honestly hadn't thought of that...

-Steve

_________________
Radio Interests
-Zenith
-Sparton
-Pre-War FM
Consoles and floor models, the bigger, the better!


Top
 Profile  
 
 Post subject: Re: COAX lead-in for BCB longwire antenna?
PostPosted: Nov Sat 02, 2013 1:06 am 
Member
User avatar

Joined: Jun Wed 14, 2006 11:49 pm
Posts: 7141
Location: Leo, IN or Zellwood, FL
azenithnut wrote:
John, your idea with a motor and continuous turn variable cap is so simple, its Genius! :D

I honestly hadn't thought of that...

-Steve


yabutt no direction indicator just a push button to run the motor Steve. It was cheap and simple and worked. Think I paid
all of 2 bucks or something like that for the 12V motor/gearbox. Added insulated coupler to variable I found in my junk box
and it was off to the races with the project.
John k9uwa

_________________
http://www.JohnJeanAntiqueRadio.com


Top
 Profile  
 
 Post subject: Re: COAX lead-in for BCB longwire antenna?
PostPosted: Nov Sat 02, 2013 4:28 am 
Moderator
User avatar

Joined: Jan Thu 01, 1970 1:00 am
Posts: 21951
Location: Somers, CT
Varicaps are made for AM tuners, and will do a 1:3 frequency range. Q might be a bit lower than a variable cap for the cheaper varicap diodes... but using a pot to set the tuning would be pretty easy.

Pete

_________________
Just because it can be done doesn't mean it should be done.


Top
 Profile  
 
 Post subject: Re: COAX lead-in for BCB longwire antenna?
PostPosted: Nov Sat 02, 2013 4:36 am 
Member
User avatar

Joined: Jan Thu 01, 1970 1:00 am
Posts: 36198
Location: SoCal, 91387
Thx Peter, but the whole point of a larger loop is to max out the Q, so I guess an air variable is the way to proceed.
I was just wondering if I could enhance the entire band, inductively, rather than having to selectively tune the loop to each frequency the radio was set at. I guess that's just not in the cards, however.

_________________
\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\He Who Dies With The Most Radios Wins/////////////////////////


Top
 Profile  
 
 Post subject: Re: COAX lead-in for BCB longwire antenna?
PostPosted: Jan Thu 02, 2014 10:53 am 
Member
User avatar

Joined: Jan Thu 01, 1970 1:00 am
Posts: 36198
Location: SoCal, 91387
Renton481 wrote:

Hi Fifties,
I don't know the gauge of the wire I used (not that savvy about wire gauges yet). It's a little bit bigger than regular radio hookup wire, and it's stranded -- about the size of speaker wire, or zip cord wire. Measuring the width of just the stranded wire, it's about a millimeter wide, maybe a little less. I would use whatever wire you've got, as long as it's somewhere around the size of hookup wire, or stranded speaker wire (stripped in half). You may have to use a few more windings than 16-25, or a few less. The plans I used called for roughly 25 turns of stranded wire, spaced 3/8 inch apart. I just wound 25 turns, and just spaced the windings a more than a wire-width, and left it at that. I ended up taking off a few windings to get the loop to tune to 1700 khz. At first it tuned from below 510 to just below 1600. Now it tunes from 510 to 1700.

The windings on my box crate loop aren't glued or secured to the crate, although I may try to eventually secure them that way. Once, after storing it away for a while, the windings on the loop got a bit bunched up, and when I started using it again, the tuning range seemed a bit reduced, to where the loop wouldn't tune past 1600. I spaced the windings back out again and it tuned into the X band again, about to 1650 or so. I then removed a couple windings and got it to tune from 510 to 1700 (I don't know if it's exactly peaking at 1700, but it does boost 1700 well enough for me right now).


Tonight I just finished putting together a four crate loop (11-12 turns of the same gauge stranded wire, all four milk crates secured together with zip ties). So far it works well,


Well, I attempted to make a loop antenna out of a 23" quilting hoop, tuner from a junked AM radio, and 75 feet of bare stranded wire from a Rat Shack outdoor S/W antenna kit. I used it because it was AFAIK the longest continuous length of wire I had on hand. The windings are right next to each other.
It gave me 12 turns, which according to what Renton481 posted above in the last paragraph, should have given me something, but no dice. I tried several radios at different frequencies, but couldn't get an affect when rotating the loop's tuner.

I'm wondering that since I'm using bare wire, if I should re-wind, and space the windings apart from each other. I also have five 50 foot lengths of insulated (lead in) wire, also stranded. Perhaps connecting several lengths together, and winding them next to each other might be better?

I have a Grundig AN200 tunable loop, which is 9 inches in diameter, and has 30 turns of what looks like painted (insulated) magnet wire, wound right next to each other.

Any thoughts on how to get this working and at the best efficiency would be appreciated.

Also, I assume the two loop connections go to the tuners antenna gang rotor solder lug, and the tuner frame?

_________________
\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\He Who Dies With The Most Radios Wins/////////////////////////


Top
 Profile  
 
 Post subject: Re: COAX lead-in for BCB longwire antenna?
PostPosted: Jan Thu 02, 2014 11:32 am 
Member
User avatar

Joined: Jul Sun 21, 2013 12:21 am
Posts: 5014
Location: Vieques,PR 00765 USA
BARE wire won't cut it. The turns may short together :roll: You can use enamelled or insulated wire. Splice pieces together if need be.

_________________
-Bill

Visit my homebrew page
www.sparkbench.com/homebrew/homebrew.html


Top
 Profile  
 
 Post subject: Re: COAX lead-in for BCB longwire antenna?
PostPosted: Jan Thu 02, 2014 11:36 am 
Member
User avatar

Joined: Jan Thu 01, 1970 1:00 am
Posts: 36198
Location: SoCal, 91387
Thx, Bill...That's a start. So I either space what I have there apart, or use insulated. I think I'll start over, with insulated. Two 50' lengths spliced together should give me 16 turns.

_________________
\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\He Who Dies With The Most Radios Wins/////////////////////////


Top
 Profile  
 
Post New Topic Post Reply  [ 85 posts ]  Moderator: Alan Voorhees Go to page Previous  1, 2, 3, 4, 5  Next

All times are UTC [ DST ]


Who is online

Users browsing this forum: beat_truck, chaz, dsturz, FStephenMasek, jimsp, simplex1040, wallyg and 19 guests



Search for:
Jump to:  


































-->


Privacy Policy :: Powered by phpBB