The AM Forum

I have finally come to the conclusion that it is time to replace the box at the base of the tower that contains my antenna tuners.  This was supposed to have been temporary, to be replaced in a couple of years.  It's been over 25 years now. Believe it or not, this was originally a console floor model radio cabinet.

I just moved it a few feet from its original position to make room for the new construction.


(http://i66.photobucket.com/albums/h269/k4kyv/Dawg%20House/olddawghouse.jpg)
View of tuners

(http://i66.photobucket.com/albums/h269/k4kyv/Dawg%20House/frontviewold.jpg)
Front View

(http://i66.photobucket.com/albums/h269/k4kyv/Dawg%20House/rearviewold.jpg)
Rear view

(http://i66.photobucket.com/albums/h269/k4kyv/Dawg%20House/woodrot.jpg)
Rotten wood


To be continued...

looks ruff



klc

I was wondering if that was gonna be on ur agenda during static season.

Time to run some buried PVC out there and get some 1 rpm motors.

A little remote from the shack action. Maybe a big NEMA wx proof box?

Yeah Don that doesn't look too good now although the hardware inside looks nice.

I was planning a dog house for the feedpoint here and I thought I'd construct a wood cabinet on four posts with a slanting shingled roof.  a hinged door with a latch would swing up and lock to give me some shelter in the rain and there would be a shelf inside with enough room to make manual adjustments until I motorize everything, and hold a lantern and a feedline stub to connect to.  

Then it occurred to me that such a shelter would be very inviting to critters and I'd open the door one night to find a 'possum or raccoon in there or maybe a skunk.  Maybe a family.   Keeping out animals presents another challenge.

So for me, the trick is to make something that protects the tuning components, but does not offer enough shelter to be comfortable for animals.  I want it up high enough off the ground so i don't have to crouch down in the snow.

Rob

That's a shelter what don't owe you no money!  ;D

heres the nema specs-


http://www.engineeringtoolbox.com/nema-enclosures-d_919.html

Derb,
Maybe you can rent the old one to some illigals...Lee,N2udf

Whatayamean? It looks great!!

Replace some wood and slap some paint on it and go another 25 years, Don!

Look at all the nice wood on the interior. Just turn that baby inside out.   :)

25 years is a damn good stretch.

The new one will be a little like the "tuning shack eastern long island" shown above, but from the photo, mine will probably be a bit smaller.  Up on stilts 2' off the ground, built with pressure-treated timbers, exterior grade plywood, rustproof fasteners, and critter-proofed as much as possible. 

One critter proofing measure will be to use a ring of metal flashing round each leg of the stilts, extending out horizontally, sort of a cone facing about 45° downwards.  Ants and  mice can't crawl out onto the under-side of the flashing and then climb up over the sharp edge to get to the top side.  I have seen farmers use that technique to keep rodents out of grain storage bins.

There will be enough room to accommodate one additional tuner, to run the vertical on 75.  I plan to gang all the tuning capacitors together and remotely tune with one reversible DC motor and gear drive.  Eventually plan to replace the buried co-ass with open wire line to the shack, probably run as a flat transmission line to feed the existing tuners.

I have concluded that the run is too long to operate as a tuned line on every band all the way to the shack, since the QSY tuning error that occurs at each quarter-wave length of line adds up and accumulates as a total.  For example, to go from 3.5 to 4.0 mc/s would most likely require shifting from series to parallel tuning somewhere along the way, with a transmission line feed point midway between a current and voltage maximum at some frequency.  From my experience the odd eighth wavelength is very difficult to tune because of the large reactive component and I don't like the idea of switching tuner circuitry over a single band.

I could use some fresh ideas on a door latch.  The house will have double doors, but I don't want a post in the middle.  I picked up some garage door opening hardware and a couple of  spring loaded bolts and plan to have a rotatable handle and  mechanism to pull open the bolts, but it looks like all that stuff is going to be hard to Rube-Goldberg together and will require some metal-work fabrication.  I could not find any kind of ready made latch locally.  I want to have a bolt at the top and bottom of one door, and rotate a handle to disengage both bolts at the same time, and have that door overlap the other one to hold it closed and seal the gap between doors to moisture and critters.

"Exterior Grade" plywood is crap, It's awful. My experience is that it won't last 5 years. It's simply interior grade plywood with one ply of waterproof glue. It splits, warps and cracks. It's often made with the softest of wood. I suggest using treated 1X12" planks and a couple of coats of oil base paint. Or consider marine grade plywood.

You can get pressure treated plywood or T111. Exterior grade is not rated as exposed siding it is sheathing. It will fail in a couple years.
How about 5/4 decking?

Check out a Home Creep Show product called "Smartside".
It's pre-primed, takes paint in one coat, wood textured, easy to handle, nailable / screwable (  ::)  ) and a 4X8 ft. sheet is about $18 to $20.
I use it all the time and swear by it.    D.

hey man, bring that shed on over hyar.  I got some stuff gotta go in it.  :D

I have never had any problem with exposed exterior grade plywood as long as, like any untreated wood in building construction, it is kept painted.  I have a piece that I used to make a shallow box for hauling dirt from under the house when I was doing some excavating, and it has set outside off and on for over 15 years with no signs of delaminating. The wood on the old dawg house is made from some scrap plywood I had lying around.  The doors and the back side were never painted, and the deterioration is from the UV attacking the wood.  The first ply is  literally crumbling, but it hasn't come unglued.  I think they make all plywood with better glue than they did a generation or two ago.

The interior of the old box is the original plywood used in the radio cabinet.  A close look at the photo shows that it has come completely unglued and delaminated.  The older stuff often wouldn't take a good soaking even once before it came apart.

On this project I am using 1/4" exterior grade plywood for the sheathing.  It will be painted, and if it begins to show signs of deterioration, it will be a simple matter to cover it with an additional layer of some kind of exterior siding.

Some of the "exterior siding" sold at the big box stores is nothing but exterior plywood with fake grooves cut in the outer layer to make it resemble planks, or it is wafer board with one ply of solid wood on the exterior face.

The only pressure treated plywood available anywhere locally was thick 5/8" or 1" stuff, and it was twisted and warped so badly that it would have taken a lot of nails or screws to make it lie flat.

BTW, just as the customers in the food market are being quietly short-changed by stealthily reducing the quantity in the box of ice cream (the half-gallon is now 1.5 quarts) or jar of peanut butter (the plastic jar is the same size but there is a huge dimple in the bottom kind of like the one on a wine bottle), the same thing is happening with building material.  You can no longer get 3/8", 3/4" or 1" plywood. It now comes in 11/32", 11/16" and 15/16" thickness.  I picked up some 1 X 2's and they actually measure 5/8" X 1 3/8".  They never were really 1" X 2", but not too long ago they were at least 3/4"X 1 1/2" in size. Of course, the price is the same or higher than the old  larger size.

Why can't vendors and manufacturers of products just be up front and honest about it.  They have raised prices.

smart side is T111 usually made of SYP rather than crap wood.
White pine 2X4 trim will rot quickly.
Yea I bought some 1/2 inch plywood Monday that was .45 thick.

Unless it's leaking, I'd keep it as is.

Where would you find another exterior Patina like that? ;D

Ok, ok, I have to admit I do like old barnwood. 8)

Phil - AC0OB

Ohhh crap!!! I bet if you make it look purty your dB's will go down.   :o


Your Bird watts will be meaningless!!!

Work has started on the new dawg house.  Notice the base of the tower to the rear and the old box to the left.


Here are the 4 X 4 stilts, sill and floor

(http://i66.photobucket.com/albums/h269/k4kyv/Dawg%20House/foundation.jpg)


Each leg is anchored to the ground using a 24" screw-in anchor designed for fence bracing.  This allowed a firm and stable foundation without disturbing the buried radial system underneath.

(http://i66.photobucket.com/albums/h269/k4kyv/Dawg%20House/anchordetail.jpg)


The framing has begun:

(http://i66.photobucket.com/albums/h269/k4kyv/Dawg%20House/startedtheframing.jpg)

A man of action! and "Comfort height" tuning. Schmart.

*A light colored paint on the inside will give plenty of reflected light. I go to the paint section of most places and get "screw up batches" for cheap or free. ( my favorite words :) )


re: Trex, It's expensive, droopy, and gets HOT in the sun.
( i've know some ladies like that....)

re: Smartside.
Now that I think about it, it might not be right for the Dawg house as you can't really secure things to it like you can with 5/8 ply or planks.

 
One last thing...( i promise  ;D )
Next election cycle, grab those "plastic cardboard" election signs when the election is over.
That stuff is GREAT for projects of all types. The election commitees are glad to have them gone BUT ask permission. I'm out at 5am with a screw gun and prybar the morning after the elections.
I was thinking in this case you could line the tuner shack with it before the exterior wood. The back is pure white and insulative.
I could write a book on what other stuff I've used it for but I'll spare ya'   8)

  * sorry Derb, the shed is a stock pic I lifted to show the "smartside" stuff. I could use a dozen sheds me self...

ok, i lied, one more thing...

As far as the door and hinges....

I found an easy way to hang plywood doors in perfect alignment.
I've used this for duck blinds, sheds & boats.

Screw the door side plywood wall in place as one piece.
Draw the out line of the door as you would like it.
Plunge cut the hinge side line only first, then install the hinge ( a brass or stainless piano hinge is best and worth the few extra bucks. )
After the hinge is secured, cut the remainder of the pattern you drew and it will be dead on.
I cut 3 or 4 inch radius corners as it is stronger and looks nice, like a steel marine door.

Consider one door, big enough for access.  It would simplify things a bit. Run some strips of that 1x1 to keep it's shape like a shed door.

Also, screen door hardware is cheap, weatherproof and works well with plywood.

 

Don, your ATU is looking to be better made than my house.    ::)

Yep it's rebuilding time all over.

I have 3 X 6 ft runs of 1" wide copper STRAP to deploy, 2 new ground rods  and some wider copper STRAP on the way.

2 advantages with the new layout: length of ground conductor from main inside grounding plate to mother earth: 4 ft.

Length of indoor feedline run from back of matchbox to outdoors : 10".

That's a good idea.  I never thought of doing it that way, but I Plan to make the doors a little wider and taller than the hole in the wall, so they slightly overlap the exterior sheathing on all 4 edges, using 2" wide strips of poplar moulding over the  sheathing to make a trim to encircle the doors, and the hinges will attach to those.  That will help keep out moisture and critters.  I  have a tool shed that is constructed that way. It must be 50 years old and is still in good shape, and rain never blows in around the door.

The tool shed is sheathed with 1/4" thick tempered masonite, except for the back wall, which is 1/4" plywood.  I have kept it painted and neither the wood nor the masonite have self-destructed, but the masonite has curled up a little near the bottom.  I'm not sure they even make tempered masonite any more. It was a popular material for making rack panels back in the 30's, and I am surprised at how well it has held up, exposed to the wx for decades.  Nothing in that shed was built with any kind of treated material. I think it was originally used to house a clothes dryer because the owner either didn't have room in the house or was afraid of fire.  It was purchased for $50 and relocated here some time in the 60's.

I had contemplated moving the tool shed and using it as the dawg-house, but then I wouldn't have any place to store my garden tools.

You ought to put a couple of 50W incandensent lamps in there to keep it warm in the winter. Or, use 12V car lamps, so the buried cable is not high voltage.

I think he should put in a mini rotating disco ball with a laser pointer that activates every time he drops that maul.

Man, the things you can do once you are retired.  I'm jealous. 

That tower insulator looks like it came from a station that ran much more than 1 kw.  5 or 10 I bet.

teh house location.

I got the tower base insulator thanks to Hoisy W4CJL in Florence, AL.  The station's tower fell due to a failed guy anchor, but the base insulator was undamaged.  They had a new tower built, but didn't want to put a brand new tower on top of a 40 yr old base insulator, so they bought a new one, and I eventually inherited the old one.  I think their power was 5 kw.  Their tower was about 250' tall and substantially larger than Rohn 25, so that base insulator is really loafing along with its present load.

It was made be a company called TCA Radio Tower Co., Atlanta GA.  I had to rework it when I got it.  The adhesive compound that affixed the ceramic insulator to the cast iron end castings had cracked and deteriorated, and the castings were extremely rusty.  I heated the whole thing, and the compound came out with the consistency of chewing gum.  There was newspaper inside the casting along with the compound and ceramic insulator.  When I removed it, you could still read the printing on the newspaper.  Never could figure out what the newspaper was for, but I took the casting to a machine shop and had it turned on a lathe to better fit the ceramic insulator.  I reassembled it using epoxy to replace the thermoplastic mystery compound used by the original manufacturer.

That was almost 30 years ago and the base insulator is still in better condition than it was when I first got it from the radio station.  That was in about 1980 or 81.  At the time, a brand new base insulator from Rohn for the 25G cost $510 (1980 dollars), and was substantially smaller than the one I have.  A few years ago, I picked up another used one, practically identical to the $510 insulator, at a hamfest for $25.  I am keeping it stored away as a spare.  Pretty cheap insurance, since if anything ever happened to the one on my tower, an affordable replacement would undoubtedly be made of unobtanium.  

Yeah the insulators for lower power are not as high.  The new ones do not taper; they are cylindrical (as if that matters).  I think the only mfr. now is Austin.  Last time I checked a new one for the smallest towers i.e. lightest load, was around $2K. 

The base pier looks good Don.  Do you have electrodes across the insulator for a lightning gap?  If you ever have to replace the insulator you'll have to work out a way to jack up the tower an inch.  it should be possible to weld heavy cross braces to the legs of the bottom section so you can put a small I beam through the base and jack it up with two hydraulic jacks that are on concrete pads.  Beats taking the tower down.  Some bottom sections have what look like upside down shelves welded to the legs that jacks can get under to lift but that only works if the bottom flares out beyond the pier.   Of course what is best is if you never have to replace it  :D  Lots of stations are still on their Lapp insulators from 50, 60 or in some cases over 70 years ago.   

That's a heck of a 160 m. antenna as I know from our QSOs on 1880.  Thanks for the photo Derb.

I'm looking forward to seeing what I can do here with some 160 action. I cant do a antenna like Don's but I'll put up something that looks sexy as all hell any way. I cant string a long ass L back behind the house. That T antenna I wanna do will work ok, I wont be the channel master, but on 160 you dont have scrape and struggle so much like you do on 75.

You'll be surprised at what such an antenna can do.  I have an inverted L that only goes up 50 feet but I am surprised at what I can do on 160 with 250 watts.   My problem is my receive stinks.  I badly need a separate rx antenna.  I have one, (1/2 of my 80 m. ladder line fed dipole) but it is no good.  I need a small rx loop.

Anyway, you now have about six months to do something before 160 picks up again.  If you decide to try the inverted L, keep in mind the horizontal part does not have to be straight.  Mine has two bends in it to get it to fit on my lot.  

The secret to any of these antennas that work against ground (and on 160, those are pretty much the only ones that really work--a dipole has to be really high, over 100 feet before you start getting anywhere and then it will be straight up) is the ground system.

Don't let anyone talk you into using a chain link fence, or something else in place of radials.  I work these guys on 160 who have crappy signals and when I find out they use inverted Ls, I ask about their radials.  Without exception I get "Oh I use my chain link fence" or, "I'm using my barb wire fence" or some other substitute to avoid the work of putting down radials.  

You have to bite the bullet and put down a copper pipe or strap radial ring or some kind of stainless steel or copper plate and braise or clamp radials to it with s.s. or brass screws.   Another place where hams cheap out is the wire.  electric fence wire, barb wire, aluminum, any bargain wire will work but only for a short period of time.  If you want to have radials you can use for years, you have to invest in copper.  Insulated is okay, even better than bare according to a paper elsewhere on this site by Archibald Doty.  Solid is easier to staple down and work with.  Get about 3600 feet of no. 14 solid for starters and you'll probably have enough for 60 radials 60 feet long or 30 120 footers.  Lots of shorter ones is better.  Fit them in wherever you can, mine are anywhere from 10 feet long to 120 feet.  If you use enough radials you won't need a common mode choke out at the feedpoint because the return current on the shield of the coax will be divided out amongst all your other radials so the fraction on the coax will be so low you won't have an RF feedback problem.   Those common mode feedpoint chokes are only for people with four radials.   Many hams (I include myself here) run into a mental block over this.  There is something crazy and counter-intuitive about blowing a heap of money on perfectly good new wire, then burying it in the ground.  If anyone sees you they'll think you have gone completely nutso.  But the results will tell you this was the right thing to do.  I had to keep reminding myself this is part of the antenna and getting return currents back to the feedpoint, like one half of a dipole.

with that T antenna and 60 to 90 radials down under it you will STRAP on 160!  Where you are near the coast you will probably even get some European action in winter.  If ur feedline is real long, (on 160 that would be more than 60 or 70 feet) you can then consider doing as Don has done and placing your tuner out at the base of the T in a dog house.

Feedline:  If you use coax, avoid use of typical ham coax (213, 58U, 8X) because even on 160 to a matched load, these can have surprisingly high losses.   If you go to one of those coax calculator web sites and put in RG213 and select a short run say, 70 feet to a matched load at 1500 watts you may be surprised at how much power is being wasted in the feedline.  It is a myth that anything is okay because 1.8 MHz is such a low frequency, or the power being used to transmit with is low.  It is worth investing in some used 1/2 inch hardline to get as much power to the load as possible.  All this stuff, the feedline, radials, tuning at the feedpoint all eliminate small portions of the total loss and have a cumulative effect in having the highest possible efficiency in RF leaving the antenna and getting propagated.  

Rob

Man, I'm jealous.

No wonder he's always 30 over 9 here in Iowa.

I am looking for some retred property in SW Kentucky for a future QTH and tower.

Nice Dog House and construction.

Phil - AC0OB

Antenna tuners do not need heat. Heat will attract animals
Don make sure you run a heavy ground wire down each stilt in case mother nature pays you a high voltage visit. There is a big oak in the woods behind the house here missing bark on one side about 100 feet from the tower.

The roof structure is taking shape.

(http://i66.photobucket.com/albums/h269/k4kyv/Dawg%20House/Rooftakingshape.jpg)


I am using fibreglass mesh made for storm windows to screen out the insects.  One of the problems I have long had with the old tuner enclosure is insects crawling between the plates of the air variables and toasting themselves.  Then I have to clean out the mess before the transmitter will make power without kicking out the overload.

(http://i66.photobucket.com/albums/h269/k4kyv/Dawg%20House/insectscreening2.jpg)


That is EXACTLY the reaction of the owner of the wire manufacturing plant that I bought the 16,000 ft. roll of #12 soft-drawn bare wire from back in 1974.  He thought I was was absolutely crazy.  Probably figured I was one of those "weirdo hippies" doing acid when I bought the wire.  His son and I shared an apartment in Cambridge for a year or so after I had moved up there.  He sold me the wire at his cost, basically just a few pennies per pound over the market price of copper, to include the "extruding fee".

I hauled the wire down here in the back of a Corolla with the rear seats removed, along with some other heavy metal.  After the trip the leaf springs never sat right in the thing again; they were almost straight instead of curving concave upwards the way they are supposed to.

Rob:

When I lived in a small nearby town on a little lot, my main antenna was an inverted L, about 55' vertical and 65' horizontal out to a mast on the garage.

It worked incredibly well on 160-40. The thing is, I did use a chain link steel fence around the back yard as a ground system- counterpoise. I couldn't bury but a few radials on the small narrow lot and there were too many trees with large roots. . Don't dismiss the use of a 5' tall steel fence as a counterpoise. It's well known now that a vertical with just a few elevated radials will perform as well as a vertical with a great many buried radials. Think in terms of a ground plane antenna, even with just 3 or 4 'radials', they still perform efficiently. The return path for the RF current is into the efficient radials, not into and through lossy earth ground below. Broadcasters are starting to come around to that concept, finding that verticals with only a half-dozen elevated radials perform as well as the traditional hundred buried radials.

You have to think of, and model an inverted L as a short top-loaded vertical. The top loading of the horizontal portion elevates the max current node, a good thing. Because of the low radiation resistance of a short vertical, including an inverted L, you need to keep the I2R losses down by using large conductor wire or braided strap for the thing. Using thin #16 gauge copper is guaranteed to waste a substantial amount of RF in heating.

The RF resistance of a 100' chunk of small wire is going to be a substantial percentage of, say, the 10 ohm resistance of a short vertical. You need to use big fat wire or strap to make an efficient small inverted L. Not only for minimizing resistive losses, but for giving the horizontal portion more capacitance to ground and raising the antenna's efficiency. Think of the old flat-top antennas hams used ages ago. You want as much C on top as you can get.

What you use for radials can be counter-intuitive, especially if you only have a few. I spent a lot of time making measurements on my L with an RF ammeter at its bottom and a wattmeter in the shack before the tuner. You can calculate the feedpoint resistance that way, which is the sum of the antenna's radiation resistance in series with ground resistance (losses). As you add to or alter the ground system, you can measure the change in ground losses. You want to shoot for the maximum amount of RF current for a given amount of RF power. The reason I suggest this is some of the grounding changes I experimented with were counter-productive. For example, I started out using the fence around the yard for my counterpoise. I measured and noted the feedpoint resistance. On one occasion, I added a grounding strap to the house water main. That additional ground made the antenna's resistance go up, not down. The same happened when I added zig-zag radials. They made the antenna less efficient. The reason for the former is that the water pipe made for a lossier ground than just the elevated fence. The added ground connection forced the RF return path through lossy earth. If I hadn't measured what changing the ground system was doing, I would have been ignorantly happy, thinking that a few hundred feet of buried water pipe was helping. It wasn't. And the zig-zagged long radials were worse than even very short, straight radials. OTOH, a roll of 3 foot chicken fencing laid on the top of the ground did help a lot.

You just gotta measure how much fire you're putting into the wire.

Well, that's way more than I intended..My two Centavos.

hmmm Don's world view is compressed and on end.  ;D

As his official photographer, we have to make sure all pic are shipshape even if I didnt take them.

It should look mo like this I think. Might need a slight height/width adjustment.

Bill, FB.  Useful information.  I would not use braid outside however.

My fence comment was about hams who's ground system consists entirely of a fence.   Your mesurements are right on and a great way to check performance.  I have toyed with the idea of tying my aluminum siding on my house and garage into my ground system but have never gotten around to experimenting with it. 

The geometry of a ground system is interesting.  The wires must extend out from the base of the driven vertical element in straight lines so they are in line with the wave front coming from the vertical element.  It is therefore not too difficult to see why zig zag radials would not perform as well.  yet,  when on the ground or buried, the proximity of earth would render the positive effect of straight line radials less significant it seems to me for on the ground, they are only collecting and returning currents from near by earth.  On that I have no explanation. 

Your comment about fewer radials pertained to elevated radials.  I never mentioned anything about them, confining my comments on the needed no. of radials to surface or buried radials.  The reason is that every paper I have ever read on top band elevated radials pretty much says that in order for them to function as elevated radials they have to be a minimum fraction of lambda to work, around .1 or .05 lambda, otherwise they are coupled to earth and are no different from surface radials.  Most hams are unable to manage the physical height requirement therefore, I limited my comments to surface or buried radials. 

The problem with chicken wire is that it does not last.  My recommendations were also based on an assumption of need for long life.  However, copper mesh if you can find it is great very close to the base of the vertical.

73

Rob

Hi Rob!

The thing is, the most intense RF return current is right at the base of a short vertical. So even short chunks of galvanized chicken fencing really do a great job. It lasts quite a while out here in this dry, dusty cowtown, perhaps not the best thing to use where there's more moisture. Yes, no question about copper mesh, but...$$$. Ever price copper or brass screen? Yikes!

Yes, you are correct regarding a minimum height for elevated radials, on 75 .05λ would be maybe 5 feet, which a 6' tall steel fence with top rails would almost cover. But over my local earth, that low height was a better counterpoise than the buried radials that I could lay out. I proved it.

My best winter DX on 160 with that setup was KH6CC. I couldn't believe working Jack on Top Band. I regularly worked out east on AM like WA3PUN.

An inverted L with a few radials elevated some 10' would perform quite decently from 160-40. Downside: That takes away 10' from the height of the antenna. Yes, they need a distance from dirt, but I saw that if you decouple from the earth, like by not using water pipes for a RF ground, even a low counterpoise works decently. Dirt really sucks as an RF ground and RF return. Forgetabout the proverbial 1/4λ or 1/2λ radials, you only need them that long if you have a lot of them. One or four that long is a waste of time, wire and effort. 10 of them, just 10 feet long, and a mesh right under the antenna, will outperform four at 60 feet long.  I proved it. (Except for very low radiation angles).

Funny- Verticals can take up as much or more real estate than elevated dipoles do. In spite of what Gotham says..LOL

You know, all of this is theory from experience and the antenna books, but the only way to do it is to actually measure the RF current in the antenna system as you make changes. You just can't calculate your local antenna environment on a computer. The books are only a guideline.

Another way to look at a 50' x 60' (or so) inverted L on 80 is you're end-feeding a tilted inverted Vee. In that case, the grounding system is mostly irrelevant The max current is going to be near the top of the thing and it will perform nearly as a vertical.

Remember the bobtail curtain for DX? Three 1/4λ verticals and the counterpoise is the horizontal wire at the top connecting them. The inverted L is just one element of the same.


Don't forget that inverted L has directionality to it. If, for example, the horizontal portion runs to the north from the vertical portion, the main radiation will be to the south. A T antenna will be omnidirectional

Good chat!

hg

I corrected the damned thing, but it keeps coming back rotated on end.  I rotated the original photo and saved it.  I uploaded the rotated and saved photo to photobucket and it came out wrong.  Photobucket has a rotating function for editing uploaded photos, so I re-rotated it there.  It came out OK when I previewed it, but now it is up on end again, and now there is the width error. It seems if I turn the camera 90° to take a picture in portrait mode instead of landscape, it wants to come out landscape mode, 90° out of kilter, no matter what.  If anyone has any idea how to correct this and make it stay corrected once and for all, I'll give it a try.  I guess with Photobucket's free hosting service you get exactly what you pay for. From now on,  I'll just take landscape photos. Not worth the hassle.

photobucket sux, always has, always will.

if my guesstimate of the proper scale is accurate,  the new dawg house looks like a mansion compared to the old one.

yep, thats it.  the rf ammeter is your best bud. I like to refer back to the late 20's very early 30's  QST's and see what the OT's were using to get on the "1750 kc band".  They would bury copper plates, brass radiators and the like. Anything to reduce the ground resistance. fun reading.

I tried again.  The preview now shows the proper image.  Let's see if the image on the actual posting stays that way.  It displayed properly on the Photobucket album when I re-checked it, so I saved the corrected image to desktop, then re-uploaded the saved version to Photobucket, and then substituted that new image link in the message.  Maybe that erased whatever code was causing it to come out wrong.

The new dawghouse has a 2' X 4' footprint, and is 4 1/2' tall, not counting the stilts or the roof gable part.  The whole structure is taller than I am.  Working on the sheathing now.  It's a real pain to cut that so it  comes out exactly right.  Even a sawblade's width of error on some of the measurements makes the whole thing come out wrong, not to mention errors due to wood warpage.  I finished the front piece this afternoon, after having to trim it twice.  Trying a different approach for the rear piece and hope to get it right first time.

I guess photobucket is kind of like slopbucket.   ;D

Speaking of radials, I just read an article in the broadcast rag Radioworld, and the writer mentioned that there should be an expansion loop in buried radials right where the ground radials are brazed to the copper strap at the base of the tower. I assume they mean  leaving enough  slack between radials and the strap to make a small loop, to account for expansion and contraction of the wire with temperature.  I had never heard of this suggestion before.  It sounds like a good idea, but it seems to me that if you use soft-drawn wire for the  radials, they would have enough give to stretch slightly under the tension during extreme cold before anything would break, and form their own "expansion loop" when the temperature warms back up. I could imagine poorly soldered radials actually pulling loose from the ground strap during cold weather, especially if something like copperweld is used.

As for zig-zag radials, wouldn't the zigs and  zags  have to be a significant fraction of a wavelength to have any deleterious effect?  I could see bending the wire at odd angles in 10'-20' sections being a problem, but occasionally zig-zagging it maybe a foot or so to dodge obstacles shouldn't be too bad, or would it? Also, many times, radials are inadvertently slightly zig-zagged during installation if the common procedure is used of forming a slit in the ground with a spade or lawn edger, and then some hard object like a stick is used to poke at the wire to push it into the slit.  But I would think that would be such a minuscule fraction of a wavelength as to have zero effect.

Perhaps the total zig-zagging would have to shorten the overall length of a radial by a significant fraction of a wavelength for it to have any effect, even if the individual zags are but a fraction of an inch or so.  You wouldn't want to spiral your radials like the binder on a notebook in order to get more wire into the ground in limited space.  You would be better off using the same amount of wire to make two straight, smooth radials, than one spiralled one. I have seen mobile whips with wire wound in a spiral over a fibreglass rod, but a whip antenna is not the same thing as a buried ground radial.

Maybe one could make a clamp-on rf ammeter out of one of those little ferrite sleeves designed to clamp over a power cord to reduce rfi.  Just wrap a few turns of wire through the inside of the sleeve, out the end, back over the outside to the other end, and once again back through the sleeve so that it acts  like a toroidal transformer, and use that to feed a diode and small DC milliammeter, and calibrate it by comparing the reading with that of a thermocouple meter.  You could clamp it over each radial one at at time to actually measure the current in each radial wire.

Sheathing is now installed.  Primed immediately to protect plywood from UV.

Still have roof and doors to finish.

(http://i66.photobucket.com/albums/h269/k4kyv/Dawg%20House/sheathingandprimer.jpg)

Yer big dawg house and yer little dawg house look a lot alike.  1/20th scale model?

The roof is done and I am now working on the doors.  Spent the weekend in Chattanooga visiting the daughter, so the project was put on hold for a few days.

This morning I discovered that I had a real Derb-esque problem, luckily in time before any real damage was done.  @#%&!! carpenter bees were attacking the framing! It never entered my mind that they would bother pressure-treated lumber, but I caught them chomping away.  I was able to swat one of them before they all flew away.  I soaked all the framing with bug spray hoping the smell of the residue will at least repel them until I can finish the doors and get a coat of paint on the wood.

Since I used small dimension framing material, with 2 X 2's for the studs, one carpenter bee tunnel would pretty much be enough to ruin the structural integrity of the wood.

Well, if it shows up, no ass-hole's gonna to tell me I have to paint over it at my own expense!

Nice job Don. I'm going to build a smaller version soon.  Sounds likethe bee's were about to TAG it with their gang sign.

Lou

Hell, thats big enough and nice enough to spend a few nights in when you have a good fight with the YL  ;D  ;D

Bad Dawg !   :o


http://www.coutant.org/doghouse/index.html

Now that's funny.  No anchors?  At least the fence stopped them before they got too far!

Hey Bill,
Instead of "quoting" your reply, I think your two centavos were worth a lot more than that.
It's when someone lets the secrets out, that it starts making sense and paramount to do it right in the first place. There's no free rides and no short cuts to the RF formulas.
There's folks like me who "ride along" and pick up the secrets from those who are in the know and take the time to use every day instruments to measure their progress and share the goodies.
Thanks.......next season I'll be a channel master.........haaaaa haaa

160M works during the Summer according to the true-blue radio folks

Fred

Don, hope you high and dry with all the flooding I hear going on down your way.

R.

No flooding here since we are on high ground, but many roads in our area are under water. They didn't do much building in swamps in the mid 1800's.  A lot of closings, and I haven't even tried to get into town.  Internet service went out Saturday and just got it back this morning. My kid lives in Nashville; his house wasn't damaged, but a lot of photos and videos of the city remind me of images of N. Orleans after Katrina.

Dawg house about finished, will post more photos as soon as I can take them.

Wind won't blow it away unless it tears it apart. It is anchored to the earth with 4 screw-ins.

We didn't lose power here, but needless to say, QRN and lightning threats have kept me off the air.

Same here.  There's been enough chance of storms plus being away all day to make it not worth the trouble to hook everything up and get on the air.

Glad U didn't get flooded out.  But a lot of Nashville classic spots under water:  Grand Ole Opry, Country Music Hall of Fame....I have not heard anything about Ryman Auditorium.  The Opry may have to move back there if it is above water.

R.

It's completed!  Now all I have to do is relocate the stuff inside.  That will be the real work, so the project is just beginning.

Plus, I have to do some finishing touches.  Since I painted the doors, they don't close well.  Looks like time for some filing, sanding and blasting (and of course touching up the paint at those spots afterwards).

I'm glad I got it painted before that 24 solid hours of pour-down rain this past weekend. If left unfinished, the flimsy plywood would have buckled and warped all over the place.

(http://i66.photobucket.com/albums/h269/k4kyv/Dawg%20House/Completed.jpg)

WOW, Don,

Looks geat !  Better than most BC DHes.   And,  YES,  Masonite is still made,  and seems as good as always.  I have been buying mine @ Lowes -- it has always been in stock at the local store.

73,  and as others have said,  your signal is  almost always S9+20 or better here on the West  Coast.      Vic

Well Done Don as I would expect  :) it looks good OM.

73

Jack.

http://www.youtube.com/watch?v=pyZD7eoHZT8

don,

that's a kick ass dawg house!  8)  Maybe we should re name it , it looks too damn good to be a dawg house anymore.

how about "electron freedom way-station"?

or "radio wave launching motel"?

"160 meter wavelength tuning unit & expansion hut"?


I'm just sayin.   :D Also, wheres the callsign?

I prefer to maintain a low profile.  I'm sure a lot of locals in the area don't know what my tower and antenna system are for, and there are several other towers in the immediate area.  This is high ground, one of the highest spots in this part of the county, and three other communications towers about the same height as mine are visible from my tower site, plus a water tower, and a cellular tower about a half mile away is hidden behind the woods. Mine doesn't get a lot of attention any more because it blends in with the rest.  I think it best to keep it that way.

When I first built it in 1981 it did draw some attention because it was the only tall tower around here except for the water tank, but the local population density was a lot lower then.

That is a really nice looking DH.  Makes the whole feedpoint look like a commercial installation with the pier, insulator and genuine Rohn bottom section instead of some JS bottom.

theres a hell of a lot of BC stations that dont have as good a ATU installation.

At the time I built it, in 1980, the bottom section cost about twice that of a regular 25G section. I think it cost me about $90.  A couple of years ago I checked, and the cost had become almost prohibitive, 4 or 5 that of a regular section, something like $400-$500.

The base insulator came from a defunct broadcast tower.  I had an adaptor plate made because the mounting holes in the Rohn base plate didn't match those in the insulator.

The matching base insulator sold by Rohn was priced at $510 in 1980.  I now have one as a spare in case something happens to mine.  Got it at a hamfest for $25.

AM tower hardware may become more available to hams in years to come as more little mom and pop AMs go dark.

I can report some long overdue work on the antenna project; I finally started work on the new above-ground feed line.  The wooden tripod is used to hold the metal poles in a vertical position while pounding them into the ground.  Got the first pole in the ground yesterday.  5 more to go, plus guys and anchors.  It has been so dry this summer that the ground is like concrete, but we just had a good rain, plus I soaked the spot using a 5-gallon plastic pail with a tiny hole in the bottom.  I set the pail with the hole right over the spot and fill it with water, and the water seeps into the soil as it slowly drips. Probably dumped 20 gallons into the spot, which is too far away to run a hose pipe from the water source.

The tuner is partially constructed, but I am still using remnants of the old tuner in the old dog-house.  Right now, only have 80 and 40m capability using the dipole.  Both 160m tuners are dismantled.

Heck just use a lexan panel with the lettering and glue a florescent tube to the inside.. one clip lead from a lamp pin to the right place in there may well light it up nicely. The CBers use to tape florescent lamps to their antennas until they figured out that was a dead giveaway for their leenyars.

Don...Nice Job!...Hell for stout....Hope to work you this winter...Good Luck   Steve

Nice Dawg house Don. Are you going to build one of those 5 wire open coax feeders? I think you said you'd like to try it.

Over.

No, just a 2-wire balanced open wire line.  Those 10' long tee posts are probably too flimsy to hold something as cumbersome as a 5-wire unbalanced open wire line. They sway almost like a chickenband whip even with nothing attached.  I had originally intended to use 1 1/2" galvanised water pipe for the poles, until I was hit with sticker shock, and couldn't find any used pipe at the salvage yard.  Wooden posts would be too difficult to plant without damaging the buried radials.

But first stage will be to re-locate my existing tuners into the new dawg-house, with the tuning caps all ganged together and driven by a reversible motor so I will at least be able to QSY within a band without a trip to the tower.  In the interim, I will run a piece of coax above ground on the poles, which will also carry the control cable to the motor.  I am tired of having to replace the underground coax every few years because the rodents chew holes in the jacket.  The present line is designed for "direct burial" but they went after that one just as quickly as they did the previous ones that were not so rated.

I will need to redesign the transmitter output matching unit in the shack before I run the open wire  line.  I hope to get that down to one unit instead of a separate unit for each transmitter. A winter project.

Use Irfanview.  It's free (really!). Very easy to use once you know a few tricks.  Very intuitive

Al

http://www.irfanview.com/

I got it straightened out using my viewer.  But that looks interesting.  Might try it out.

Posts for above-ground feed line and control cable all set.

I probably shouldn't have  located it directly beneath a set of guy wires.

Plant some flowers under the drainage from the roof...it will self fertilize when it rains.

I like the peek-a-boo window with the ceramic insulators.

some see eyes, some see b

I finally got all the array of antenna tuners ganged together and working.  Here are some photos.

Here is what you see when the doors are opened, with close ups of the 80m dipole tuner at the bottom of the house and the 40m dipole and 160m vertical tuners up above.

At the bottom right is the 80m vertical tuner.

Here is a close up of the selector switch handle, the 160m dipole tuner + motor/worm drive assembly, and a rear view of the dawg house showing the OWL to the dipole and the feed wire to the base of the vertical as they exit the house.

Here is a side view of the house showing the interim coax link that runs to the shack and SO-239 adaptor attached to the twin ceramic feed-throughs, the 60-ft of OWL added to the main feed line when using the dipole on 160, and the terminating pole carrying the overhead coax, rotor cable that operates the remote tuning system, and both ends of the 60 ft OWL section as they exit the house.

Don, beautiful work, congratulations.   The homebrew feedline, ceramic insulators...edge wound coils and porcelain shaft insulators all very AMish and buzzardly.   Where did you get the dpdt knife switches?  I have one just like them I got at a hamfest waaay back in the 1970s when I was a novice and I have hung on to it ever since.  I have never seen another one like it for sale at any fest since.   I think mine is mil. surplus.

Rob

Mine are mil surplus.  Some are marked "US Army Signal Corps".  I modified mine slightly.  Got rid of the steel nuts and washers and replaced them with brass.  The nuts were soldered to the other metal parts, so I had to get out my jumbo soldering iron with 1" tip.  I never use ferrous metals anywhere near rf or where any electricity is conducted.  I picked up one here and one there over the years until I had accumulated enough for this project.  One of those shown in the photos is spdt while the others are dpdt.  I still have another one that is 3pdt.

Sounds like another example of the good stuff that's unobtainium now.   Glad I hung on to mine.

Beautiful, Don!

I love that bigassed switch~!

Those pictures are awesome Don. It's obvious you have spent many years thinking and planning this project because it shows. Hand made perfection......

Mike

I have all three of the military RF knife switches you have described, Don. I found mine while dumpster diving (something I readily admit to doing at every chance and I have no embarrassment in admitting it, either) at a big radio yard sale here on Long Island about 10 years ago. The amount of good, usable radio and electronic stuff (parts mostly) in that 40-foot long dumpster was amazing, and it was all going to be hauled off to the local landfill otherwise. Heaven only knows how many times this kind of scenario has been repeated in the past, and will again in the future. I'm glad I was able to rescue and put to use what I could from that pile.

I use the DPDT switch to ground my open wire transmission line when the station is not in use; it is military-nomenclatured as SA-13/U.

I also replaced the hardware on this DPDT switch, which is the only one of the lot that I am currently using, but I used stainless steel fasteners instead. I really don't know if there is any meaningful or measurable difference performance-wise between brass and stainless steel in this application, but I suspect any difference between the two materials is probably negligible.

That is is very nice doghouse you built, from both an appearance and functionality standpoint.

73,

Bruce

Wow.  I can't imagine anyone throwing those in a dumpster, particularly at a radio yard sale, assuming the sellers had even the slightest clue of what they were trying to peddle.

I have seen those things listed on ePay get into the $50-$100 range.  I got all of mine at hamfest flea markets for a few bucks each, or found them in a $10 pile of junk filling a box under a vendor's table, but that was 20 years or more ago. I seem to recall seeing one or two at Dayton recently, and they were a little too pricey for my interest.

I have three in the dawg house; one to ground the OWL going up the tower, one to ground out the vertical and the third one for  the feedline that comes in from the shack.  I also have a 4th one, a dpdt set aside to go into the shack when I build the OWL run from shack to dawg house.

For additional lightning protection, each one of the two messenger wires carrying the coax and rotor cables from shack to tower is bonded to every metal pole that supports it. The poles are about 28 ft. apart and there are 6 of them, each driven to a little over 2 ft. into the ground.

Come to think of it, Don, I found two more of the those big-ass DPDT RF knife switches at Deerfield/Nearfest back in May of 2008, and they were very cheap as I recall; something on the order of $5.00 for both of them. I picked them up from a guy who also sold me an unused RCA 833A and some other sundry broadcast-type stuff at an extremely fair price. Those switches are staying on the shelf for a future antenna project. They can still be found, and I'm sure there are many hams out there who have squirrelled them away over the years, like me.

73,

Bruce

Outstanding work Don! I'm loving the antenna selector switch. This should serve you well for many years to come.

Too bad they just don't make hardware like that anymore.  :'(

Just our of curiosity I checked Fair Radio and Surplus Sales and they both had zero knife switches which I found kind of surprising.  Then I searched knife switch on ebay and got a bunch, mostly cheap plastic garbage.  There were a few that looked buzzardly but nothing like those big mil. surplus switches we have.     But get this, the few that almost looked okay were eye-poppingly high priced, anywhere from $100 to $300!!  For a frigging knife switch!   Damn, i guess I'd better put mine in a safe deposit box.     You better put a lock on yur dog house Don!  you never know, you might have a crack head in your area.

You could build your own knife switches for a lot less.

Here are some more pictures.  For some reason, it will only let me post two attachments, so the rest will follow.

The rack-mounted remote tuning control/indicator unit

Control/indicator unit rear view

Tuner/antenna selector switch.  Homebrew, assembled from parts taken from five large ceramic 10-pole rotary switches.

View of the coax and rotor cable entrance to shack.

The black wire used to connect to the switch is #8 stranded with plastic insulation and fabric sheath.  This was used instead of solid wire or copper strap to allow the wires to be moved without putting excessive stress on the switch tab terminals

You've pegged the Coolness Factor meter! Thanks for the photos.

Very coool. All you need is someone to run outside and flip the switch for you

A ham in Ohio gave me a stepper motor and TTL logic board.  I am going to try to get it running, and if it displays enough torque, use it to rotate the selector switch remotely from the shack.