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Making a Beverage Transformer Box de K0FF

K0FF (K0FF) on January 22, 2010
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KØFF Homebrew Tips

Weather Resistant Beverage UNUN
Constuction DE KØFF

The cast aluminum box is an electrical department item. Made for outdoor lighting junctions etc. This one is called a single gang, three hole. A gasketed blank cover is selected to fit, along with some threaded aluminum plugs. Stamped right on the box and cover, it says "Suitable for Wet Locations". Smear a little SILICONE GEL on the edges to keep the gasket supple:

In order to mount the Brass 5 way binding post, one of the hole plugs was punched using a 1/2" punch. This makes a hole with a flat side, and that mates perfectly with the connector, so that it won't spin. Brass nuts hold the 5 way assembly secure, and the plug is bottomed out in the top hole. A few drops of Locktite Outdoor Fixture Adhesive (Home Depot) keeps the plug in place, and further waterproofs it.

Inside you can see the Toroid, it is wound according to designs in ON4UN's book, "Low Band DXing", and this one is a large core. In many applications a similar transformer on a smaller core is used. Fiberglas tape is wrapped around the homemade aluminum bracket, which itself is held down by a stainless steel screw. The TyRap secures the core from moving, and simply passes through two holes punched in the bracket:

Notice the routing of the wire coming from the antenna wire. It is made to run parallel to the side of the box, with a little space in between. This is merely an effort to control the arc path in case of lightning. Later designs included spark gap devices as well. Notice the conduit fitting on the bottom panel. . I use a 6 foot section of copper water pipe as the ground rod, the top of which slips into the conduit fitting, supporting the BevBox. A sparate heavy ground wire is clamped to the rod and attached to the big brass screw on the bottom panel.lightning ground is provided via the big brass screw shown on the bottom panel. (Note, copper pipe makes a good, inexpensive ground rod. To install it, slip a regular ground rod inside then work the pair up and down in a shallow hole filled with water. On each stroke, it will go deeper into the earth, no pounding needed. When it is as far as you want, slip out the rod fro use on the next pipe).In this unit the silver/Teflon type M (UHF) connector comes out the bottom also:

 

Some versions have the connector coming out the back:

It seems that every Low Band DX'er prefers his own brand of transformer.
Large Core, Small Core, Binocular Core etc.:

Whatever your preference a few standard mechanical techniques apply. Wrap round core with Fiberglas Tape to keep the wires from chaffing:

Dip the finished transformer in Q-Dope:

The third hole is sealed with a plug in this instance. Just before we seal her up, a packet of dry Silica Gel in wedged in place:

Sealed boxes used outdoors need the breathe a little bit. Screened hole plugs work great but are a bit hard to find today. In my designs, a small hole is drilled in a brass screw, which is then threaded into the boady of the box. Smallenough to block insects but pass water vapor. This weephole can be easily replaced should an insect decide to plug it up!:

 

Final Thoughts:

For reference, see my other eHam article Beverage Hub. My Beverage's (all single wire) are designed to use 75 Ohm cable, which I picked up for nil surplus. They are installed all around a 10 acre tract, some far from the shack. Some of my Beverages are fed at both ends. These use a version of this BevBox but with a Bias Tee and relay inside. The relay will drop the transformer out and insert a load resistor instead. At the other end, the load resistor is dropped out and the transformer inserted.

At the Bev Hub, the particualr coax is selected and sent to the shack. Some of the Beverage's terminate at the Bev Hub, that is their single wires are fed from there. These are relay selected and matched by the Bev Hub switching.   One is a 500' #10 Ga. copper wire running off the bluff, in a southerly direction. It has worked me some outstanding DX contacts.

  Lightning is a real concern when your whole house and property is 150+' above the surrounding ground level. My station was designed with lightning protections as the primary design element with feedline loss coming in as priority #2.   Later on I will discuss my "single point grounding system", tower grounding, proper installation of TVI, LP filters and lightning arrestors, AC power protection, wind, feedline loss concerns and other factors that went into the original layout of my 7 tower HF-UHF sytem on the edge of this bluff:  

 

See you in the pileups,
Happy Building, Geo KØFF

Member Comments:
This article has expired. No more comments may be added.
 
Making a Beverage Transformer Box de K0FF  
by K9ZF on January 22, 2010 Mail this to a friend!
Cool.


73
Dan
--
Amateur Radio Emergency Service, Clark County Indiana. EM78el
K9ZF /R no budget Rover ***QRP-l #1269 Check out the Rover Resource Page at:
<http://www.qsl.net/n9rla> List Administrator for: InHam+grid-loc+ham-books
Ask me how to join the Indiana Ham Mailing list!
 
Making a Beverage Transformer Box de K0FF  
by WD9FUM on January 22, 2010 Mail this to a friend!
Thanks for a super article - 73!
 
RE: Making a Beverage Transformer Box de K0FF  
by KG6WLS on January 22, 2010 Mail this to a friend!
Another article well done. Thanks, Geo.

73
 
Making a Beverage Transformer Box de K0FF  
by K5END on January 22, 2010 Mail this to a friend!
Nice presentation and photos.

Kudos for pointing out the need for a weep hole.

Thanks for putting together and posting.
 
RE: Making a Beverage Transformer Box de K0FF  
by K0FF on January 22, 2010 Mail this to a friend!
It sure would be nice to find a source of those 1/4" snap in screened plugs. They work perfectly for the purpose. They used to be abundant in the surplus market.

Geo>K0FF
 
RE: Making a Beverage Transformer Box de K0FF  
by K0FF on January 22, 2010 Mail this to a friend!
It sure would be nice to find a source of those 1/4" snap in screened plugs. They work perfectly for the purpose. They used to be abundant in the surplus market.

Geo>K0FF
 
Making a Beverage Transformer Box de K0FF  
by N6RK on January 22, 2010 Mail this to a friend!
Maybe I am missing something, but it appears that the design connects the ground rod to the coax shield. This is not recommended, as it can allow noise on the coax shield to add to the antenna signal. The beverage ground should NOT connect to the coax shield.

The transformers appear to be wound so as to maximize leakage inductance.

The ground rod installation procedure (work it into wet ground) may work in some areas, but is useless in hard pan, which is waterproof. In those areas, ground radials make a lot more sense.

The dessicant is wishful thinking. An outdoor box like this will want to fill up with water; fortunately a weep hole was included.
 
RE: Making a Beverage Transformer Box de K0FF  
by K6AER on January 22, 2010 Mail this to a friend!
Although I have ON4UN's book, many do not. The article has very nice photos but their is no technical system description nor is there schematic diagrams on the whole system. There needs to be a description on the winding details for the toroids other than pictures.

When submitting an article, the article needs to stand on its own with the proper diagrams and schematics where necessary. Also a technical tutorial would be nice on how beverages function. For those with out hardback technical publications, I would visit W8JI web site to lear more about beverage anteas.

With out wiring diagrams, confusion will rain. Speaking of rain, the weep hole in not large enough to overcome surface tension of water. With temperature cycling, in a humid atmosphere, the tiny weep hole will fill up the box with water. Either the box has to be well sealed or the weep hole must be large enough for water to naturally drain with another air hole for pressure equalization.
 
RE: Making a Beverage Transformer Box de K0FF  
by K6AER on January 22, 2010 Mail this to a friend!
It appears my 'n' key is intermittant.
 
RE: Making a Beverage Transformer Box de K0FF  
by K0FF on January 22, 2010 Mail this to a friend!
Thanks for you comments.

The first rule of Low Band DX'ing is "get a copy of ON4UN's Low Band DXing". Better yet get all the editions.

Jon's work is copyrighted and as an author I appreciate what that means. Since I can't improve on his work, I will continue to reference his work.

What I can show are unique individual mechanical applications. If I may mention it, Im have complex electronic equipment mounted outdoors since the mid 1970's still functioning today. We used the screened plugs in those.

My coax cables are always grounded at the Beverage end. I can show how this is an advantage with a
photo of what happened to this particular transformer when the antenna was finally hit by lightning after 15 years of being up.
http://www.qsl.net/k0ff/BevBox/Boom.jpg

That cover plate blew off and was several feet away.
I am quite happy with the performance of this BevBox in that circumstance.


The coax I use for Beverages is Triax, a kind of coax with two separate shields. The inner shield is
grounded at both ends, the outer shield being only grounded at the entrance panel's single point ground.
A "common mode" filter was originally constructed to further reduce RF being introduced via the shield but
in practice was never needed. Does everyone understand that your lightning protection and RFI filters need to
be at the ground panel, not at the rig?

If anyone is having that problem I can post that article here, otherwise check Towertalk archives.

This type of weep hole is a "breather", made to pass water vapor. Works well. In the above picture, sealing the box well was
tried, no weep hole. It didn't work.

If there is interest in the general concept of coil winding, preparation, sealing, testing etc. I will be more than
happy to post what I have done in that area.

Geo>K0FF









----- Original Message -----
From: <Articles@eham.net>
To: <K0FF@ARRL.NET>
Sent: Friday, January 22, 2010 1:57 PM
Subject: [Articles] RE: Making a Beverage Transformer Box de K0FF


> Posted By K6AER
>
>
>
> Although I have ON4UN's book, many do not. The article has very nice photos but their is no technical system description nor is there schematic diagrams on the whole system. There needs to be a description on the winding details for the toroids other than pictures.
>
>
>
> When submitting an article, the article needs to stand on its own with the proper diagrams and schematics where necessary. Also a technical tutorial would be nice on how beverages function. For those with out hardback technical publications, I would visit W8JI web site to lear more about beverage anteas.
>
>
>
> With out wiring diagrams, confusion will rain. Speaking of rain, the weep hole in not large enough to overcome surface tension of water. With temperature cycling, in a humid atmosphere, the tiny weep hole will fill up the box with water. Either the box has to be well sealed or the weep hole must be large enough for water to naturally drain with another air hole for pressure equalization.
>
>
>
 
Making a Beverage Transformer Box de K0FF  
by AC0GR on January 22, 2010 Mail this to a friend!
Doesnt the presence of a weep hole negate the need for silica gel? The gel would be useless after a couple days of 'breathing'.
 
RE: Beverage Transformer  
by K6SGH on January 23, 2010 Mail this to a friend!
Now, if we could pour in water and beer would come flowing out...that would be my favorite beverage transformer.

--de k6sgh
 
RE: Making a Beverage Transformer Box de K0FF  
by K0FF on January 23, 2010 Mail this to a friend!
"Posted By AC0GR

Doesnt the presence of a weep hole negate the need for silica gel? The gel would be useless after a couple days of 'breathing'."

Correct. The article was originally from the early versions without weepholes, used the gel. Added weepholes to the transformers and article later, dropped the gel. Hundreds of these were made, so a lot of evolution went on. Later versions included a spark gap and series capacitor/DC block and some even had shunt inductors. All to help control lightning and static.

Eventually use all large inductors too, in the belief that they would not saturate on strong out of band RF signals. I see that the ICOM Pro 3 uses large inductors now, for same reason.

Thanks for noticing that.

Geo>K0FF
 
RE: Beverage Transformer  
by K0FF on January 23, 2010 Mail this to a friend!
"Now, if we could pour in water and beer would come flowing out...that would be my favorite beverage transformer.

--de k6sgh "

Ii might work for wine, but only at weddings.

Geo>K0FF
 
RE: Beverage Transformer  
by K5MO on January 24, 2010 Mail this to a friend!
Screened hole plugs are available from Keystone, I believe.
 
RE: Beverage Transformer  
by K9MHZ on January 24, 2010 Mail this to a friend!
Are those the kind of plugs installed at the bottom of new exterior bricks on homes and buildings...in the mortar where weep holes would go, that is?

Brad, K9MHZ
 
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