[murf]

When I finally got around to building my first one. With a little help from Xray, she really works well. I'm really impressed with it's performance. I have to say it rivals my 160' long-wire on the BCB depending. Plus it really cuts the neighbor induced noise, which is an issue around me

Cost = $15. I'm counting the wire used along with other small odds and ends. I stripped the tuner from one of my junk AA5 sets. It measured about 10 - 467 pf on the tuner. So I used 15 winds for the main loop, and one wind for the sense loop. Connected the sense loop to A/G and the tuner to the main loop (for those that may not know already). I'm sure this is old hat for some of you, but new for me

I tweaked it some with a spacing of .100 between the 15 wind strands. I ended up bringing them together butt up against each other, but noticed no real difference except it now tunes below 500/kHz. I'll probably play around a little with the spacing to see what it does above and below. Anyhow it's no museum piece like some of them I've seen. But it tunes the whole band very well. I stuck it on a lazy-Susan so I can easily turn it for direction. Specs are;

One Philco 37-630 (Philco not required but preferred )
18" x 18"
10-467/pf tuner
24 gauge magnetic wire
15 turns (spacing can vary)
1 turn sense loop spaced 1" below main loop.

Some of you guys should consider trying one, especially if you lack space for a long wire. Fun to build and the performance is really amazing. I'm planning on another I'll slap together this weekend. Working out the specs now. So do any of you fine gents have or have built loops? If so show us what you have. Tell me you most guarded secrets to a well built loop

Looks interesting.Would like to build one and try it.
Do you have detailed drawings?
Thanks
murf

[BDM]

Plenty of choices. What is it you want to build? Do you want to mimic my 25" x 25"? Let me know and I'll post the dimensions to building that antenna. I would say a 20/25" X 20/25" would be a good compromise between size and performance. Anything larger may be getting a little large for the average living room. Especially if you have little ones around, it will only be a matter of time before someone destroys your creation. It's easy to do. H**l even my cat found my little antenna "interesting". After a good swat and yell he's decided to leave it alone Do a "bcb loop antenna" Google search and see what's out there. It doesn't have to be scientifically built. Just following a few simple rules and it should work well. None of the dimensions are critical so to say. One thing I've learned is you'll want a variable cap that drops to at least 10/pf and goes up to 400/pf or better. This will allow easily full coverage of the BCB.

[murf]

Plenty of choices. What is it you want to build? Do you want to mimic my 25" x 25"? Let me know and I'll post the dimensions to building that antenna. I would say a 20/25" X 20/25" would be a good compromise between size and performance. Anything larger may be getting a little large for the average living room. Especially if you have little ones around, it will only be a matter of time before someone destroys your creation. It's easy to do. h**l even my cat found my little antenna "interesting". After a good swat and yell he's decided to leave it alone Do a "bcb loop antenna" Google search and see what's out there. It doesn't have to be scientifically built. Just following a few simple rules and it should work well. None of the dimensions are critical so to say. One thing I've learned is you'll want a variable cap that drops to at least 10/pf and goes up to 400/pf or better. This will allow easily full coverage of the BCB.

I think the 20x25 would be a good size for a bedroom application.
Thanks pal,
murf

[BDM]

I'll do a little write up as soon as I can.

[BDM]

[Image: http://i487.photobucket.com/albums/rr233...ant1-1.jpg]

[Image: http://i487.photobucket.com/albums/rr233...ant2-1.jpg]

[Image: http://i487.photobucket.com/albums/rr233...ant3-1.jpg]

[Image: http://i487.photobucket.com/albums/rr233...6/ant4.jpg]

[Image: http://i487.photobucket.com/albums/rr233...6/ant5.jpg]

[Image: http://i487.photobucket.com/albums/rr233...6/ant6.jpg]

[Image: http://i487.photobucket.com/albums/rr233...6/ant7.jpg]


I'll refer to the antenna pic numbers for reference. The X arms are 1/2" molding stock from Ace Hardware. You'll need 4 total at 36". Then use the extra you cut off to make the center wire (tank coil) support dowels. The center tank coil dowels are 2 3/4", though 2 1/2" would work fine also(pics 5 & 7). The center box support piece adds strength against flexing, it is the same width of 2 3/4" but is 1" stock molding(pic 4). I used 3/4" long brass screws. One on each end to attach the main loop supports to the main X arms. I used fairly small screws and drilled the holes for them. If you don't, you'll split the wood turning them in. Sorry I do not have complete screw dimensions as I had them in the screw box. I just know their length.

Now I set the tank coil support dowels in 1/4", to help bring the wire inside the X arms. Then should you choose, get some balsa wood, and attach them parallel to the wire to protect it against bumps and falls. I already dropped my 30" loop and destroyed the wire. I re-wound it, but had I included this protection nothing would have happened when I dropped it. Doesn't look as sexy, but sure protects it well.

Next I worked on the tank coil dowels. I cut about 20 slots using a hand-held wood saw. If you have access to a band saw, that would save time and look more precise. Anyhow I cut them about 1/16" deep across the dowel. I used 20 cuts to allow for more winds than are needed. With this setup only 15 turns are needed. Though when you wind it, use 17 turns. That way when you tune the antenna for both the bottom and top end of the band, you can remove wire as needed. Easier than adding it. Some folks use taps with gator clips to achieve proper BCB band tune. But again doesn't look as sexy.

Next the sense coil (loop) is 3/4" from the main loop. I used very small eye screws to support the sense loop. The eye screws were purchased at Home Depot some time back for whatever reason. Again the actual size I do not have other than they were about 1/4" in length.

The main support bar that supports the X arms is 1" molding stock cut to 15" in length. Another warning if you do not work with wood. Drill all holes for the screws including the eye screws. If you do not, you stand a good chance of splitting your wood. The base board can be anything for the most part. I used counter top wood which is thick/dense and heavy. Though it's very smooth, sands out nice. Then add rubber feet to the bottom. For this loop I used a 10" x 7". Use your common sense and keep in mind you don't want it to easily tip over. For the tuning cap I used a 10/pf - 470/pf. Though I found a 10/pf - 400 works well in allowing you to tune the entire BCB. With a smaller one you can add capacitance to the tuner if needed.

Parts used:
Wood
#26 awg
25" x 25" with 15 turns
1 turn loop sense
Tuning cap that has the range of 10/pf - 450/pf

Attach the sense loop to antenna and ground. Remember, many of the 1935 - 39 sets have multiple antenna connections. The reason is if you're using a simple long wire or doublet/dipole antenna. Many of the manufactures sold these readymade. Now they have shorting bars on the connections for use depending on your antenna type. I found the best performance is seen when keeping these connections in their default settings for use with a long wire. Also do not connect a ground to the chassis when using a loop. With your new antenna connected up. Start at the top of the band and see if you get a fairly sharp tune. Then move to the bottom end and check the same. Removing windings brings the resonate freq higher(shorter antenna length). Also adding capacitance to the tuning cap drops the resonate freq lower.


Last here is my thoughts on this. I'm no wood worker, I'm no electronics engineer. Forgive my noobish approach for those that probably can be called experts. But I built this simple antenna sitting on my butt with nothing more than a drill, small wood working saw, soldering gun, screw driver, ruler and extra parts laying around and a couple of trips to the hardware store. Plus no plans, I built it as I went. Drawing up the idea in my head. There is nothing special here and no magic. It's been done to death and explained in painful detail on the net within 100s of web pages. There are probably 1000 different ways to build this to serve your needs or curiosity. Different shapes types and sizes. Some like spiral designs, others (myself) prefer the box style. Some could care less as long as it does the job, picking up the desired signal and leaving out the crud that gets normally dragged in. Remember this is the same tuned antenna on the back of your late 30s and post WWII sets. It's the same antenna in your transistor radio (at least in principle). Like those antennas it works the same way and allows your 30s sets that require a long wire to run without it. Performance can be dramatic against other forms/styles of antenna depending. These help eliminate some of the noise brought into your set(in effect a tuned circuit). It allows directional use, thereby eliminating or reducing an interfering station. Remember it's a hobby, so have fun and experiment

[murf]

Thanks for all the info.
I will try it out when I have time.
murf

[BDM]

I found this to be a really good read on loops.

http://173.201.227.192/docs/Radio/Antenn...s_2004.pdf

[Steve Davis]

OK, this thread has gotten me a little excited. We have been living in an apartment for the past couple of months, with no place for a decent long wire antenna. I was trying to use about twenty feet of wire laying along the baseboard. One of my favorite stations is 650 WSM in Nashville and I had pretty much given up on that. I put together an 18 x 18 loop. Now I am able to get WSM very clear with very little fade. Color me sold!

[Image: http://i985.photobucket.com/albums/ae335...4_3215.jpg]

Steve

[BDM]

Very nice. These loops can be addicting There as much fun to design as well as make. Plus they cost very little. This is a great example of someone who has very few choices and is now able to now enjoy their sets far more than before. Throw some stain on that and you're all set for the Grand 'Ole Opry

p.s. Experiment further with other designs. Try going to a 25"x25". Even a 30" if you feel you have the room.

[murf]

OK, this thread has gotten me a little excited. We have been living in an apartment for the past couple of months, with no place for a decent long wire antenna. I was trying to use about twenty feet of wire laying along the baseboard. One of my favorite stations is 650 WSM in Nashville and I had pretty much given up on that. I put together an 18 x 18 loop. Now I am able to get WSM very clear with very little fade. Color me sold!

[Image: http://i985.photobucket.com/albums/ae335...4_3215.jpg]

Steve

Nice setup.
Would you have a wiring diagram?
Not sure how to wire that condensor.
Thanks
murf

[BDM]

Main loop (tank coil) attaches to the tuning cap

[Steve Davis]

Steve
Nice setup.
Would you have a wiring diagram?
Not sure how to wire that condensor.
Thanks
murf

Murf, the antenna consist of two coils, the tank (main) and the sense. I used 15 turns on the tank coil (I may remove one turn because mine won't tune the high end of the band.) As Brian said the two ends of the tank coil connect to the tuning cap, one to the frame and one to the other terminal ( if you use a two gang condenser, use only one gang.) The sense loop is one turn, spaced about 3/4 inch from the tank coil. The sense loop connects to the radio, one end to the ground and the other to the antenna terminal. Also as Brian said, you might try building a little larger.

Steve

[BDM]

If you use a two-gang tuner, use the larger of the gangs (more plates). That has the wider PF value.

[etech]

Brian's posting got me fired up to build a loop, which I had been planning to do for years. Here are a few pics of the loop sitting atop my Gold Dial Silvertone model 4586.

[Image: http://i135.photobucket.com/albums/q136/.../Loop5.jpg]

[Image: http://i135.photobucket.com/albums/q136/.../Loop3.jpg]

[Image: http://i135.photobucket.com/albums/q136/.../Loop4.jpg]

[Image: http://i135.photobucket.com/albums/q136/.../Loop1.jpg]

This is a pic of the base showing the 1/4 inch rod used to allow the loop to rotate.
[Image: http://i135.photobucket.com/albums/q136/.../Loop2.jpg]

I used some wire from an old tv yoke coil found in my junk box. I think it was about 26 or 28 gauge. The base was the bottom from an old trophy long since discarded. Much of the hardware was also found in the junk box. About the only things I purchased were the 1/2 inch square molding pieces for the loop arms and the 1 inch square molding for the stand. The terminal strip used to terminate the loop windings was also from the junk box.

I still need to find a small wood box to mount the tuning gang in. I will stain it and mount it permanently to the base. The loop tunes very sharply and receives quite nicely. Well, that is about all for my little project.

Ed

[BDM]

Hey, that loop looks familiar Nice job Ed.