Stainless Steel

[N6WDR]

Would it be ok to use a stainless steel plate for my ground radial system for my vertical vise aluminum?  Would it make a difference?
I have a 2'x2' piece just laying around and would like to use it

Whats your thoughts.

Richard

[KA0HCP]

MFJ sells 'em, so it must be good! 

Besides imagine the saved hours of drudgery spent polishing, and no longer the embarrassment of having guests seeing the tarnished antenna farm.

In any case, we use stainless fittings, nuts, bolts, washer in nearly all our antennas without problem!

[K1JJ]

Normally, SS is not a good conductor of RF. Plus, the base of a vertical is a low impedance area, in the order of 30 ohms when using 60 radials or more.

But the one thang going for the idea is that the large cross sectional conductor surface area of a 2'X2' plate should wash out any worry about losses using SS.  It's the same effect as using say, a #24 copper wire vs: #6, etc.

Assuming you can bond the copper wire (or whatever you use for radials ) to the SS plate properly without corrosion or rectification problems, I'd say to use it with confidence.

T

[N6WDR]

Cool  Thank You for the responce.  I will be using Penitrox on all the connections so that should help with the corrosion factor I hope, plus it will be all stainless hardware.

Richard

[K5UJ]

Before I knew better I got the DX Engineering s.s. radial plate and used it.  Still do.  S.s. will work okay if as JJ said, you have enough surface area.   but a copper bar or wide strap with radials braised to it is probably better.   you don't need noalox or anything like that.   You need s.s. nuts, bolts, star and lock washers.  use a couple socket wrenches and snug everything down tight and it will be fine.  I set mine up that way with 101 radials about six years ago and last october went out to it to add a copper strap to a brass lightning ball gap and the nuts and bolts were just as tight as they were when I put them on six years ago.   Some vendors sell a radial plate made of aluminum but you'll get into problems with that and copper if they are in direct contact,  plus some soils eat it up.  You have to use brass between copper and aluminum.  If I had it to do over again I'd go the copper strap braising route, but since you have the s.s. plate you may as well use it if it is drilled out.  one note, my plate is above ground an inch or two so it has not been buried.   I don't know if burying it would have adversly affected the connections or not.

Rob

[k4kyv]

I would use a piece of 3/8" copper tubing as a grounding ring around the base of the vertical.  Braze the radials to the ring using a Mapp Gas torch and silver alloy brazing rods.

Although not dirt cheap, the torch and brazing rods are relatively inexpensive because they are widely used by plumbers.  It is now against code to sweat copper water pipes using lead/tin solder, due to the current concern over lead poisoning, so the silver alloy is used instead.  My experience with soldering radials to the grounding ring with lead/tin solder was that in about a month, the solder turned to a white powder and the connection literally fell apart.  I had to go out and re-solder all the radials every few weeks.  Electrolysis with the dissimilar metals in contact with wet soil ate the lead solder up.  The same thing happens with lead solder in water pipes in the reaction with natural minerals in the water.  Lead soldered pipes will likely spring a leak with time, and as the solder deteriorates, lead compounds leach into the water. I probably have a toxic spot in the ground where that old vertical was located, after repeated re-soldering of the radials over a period of several years.

Brazing with the torch is a piece of cake.  It works just like soldering any electrical wire.  No flux is needed; copper sucks up the molten alloy just like a sponge soaks up water.  Just use a wire brush to remove any scaly crud.  The copper doesn't have to be polished to a brilliant shine.  The copper must be heated to a dull red before the alloy melts. One precaution: it is very easy to melt the copper wire to a blob if you allow it to overheat. 

The brazed radials on my vertical have been buried in the soil for almost 30 years, and there is absolutely no sign of deterioration at the soldered connection.

OTOH, I recently checked one of my guy anchors that got bumped with a tractor, and  although it appears that the anchor rod was not structurally damaged, I noticed that the buried ground clamp that grounded the guy anchor to an external ground rod for  lightning protection was so loose that I could wiggle it by hand.  The tractor did not touch the clamp.  I suspect the freeze-thaw cycle in the ground eventually causes it to work loose.  The same thing will probably eventually happen with a screw-on grounding plate.

I can't understand why hams don't want to braze their radials and instead, prefer to use one of those flaky radial plates. I never heard of a commercial station using screws or clamps to attach their radials to the common grounding point.

[4cx250]

Hello All!

    There are many types of stainless steel out there. Some of them WON'T even conduct electricity!

     Just be real carefull with what you use!!!!

Tnx,

[flintstone mop]

I have graduated from the lowly ground radials to elevated radials. But I agree with Don. for the copper tubing and silver solder. The solder flows very nice and has a very nice appearance of a professional flow compared to lead solder.
I'm getting very nice reports from my elevated radials BTW and a short vertical on 160M

Fred

[K1JJ]

Well, here's the common metals resistivity. The lower the number, the better conductivity.  Notice that stainless steel is 42 times less conductive than copper.  Regular steel is not all that bad compared to poorer SS.

 Also notice that regular solder is not all the good - add in some silver for better specs.  Mercury sucks - so much for using mercury switches for RF.

Silver, alum, gold and copper are the best as expected.

If you have any plutonium sitting around, better forget about using it for Yagi elements... 

T


aluminum 26.5   
brass 64   
chromium 126   
copper 17.1   
gold 22.1   
iron 96.1   
lead 208     
mercury (0 ℃) 941   
manganese 1440   
nichrome 1500   
nickel 69.3   
palladium 105.4   
platinum 105   
plutonium 1414   
silver 15.9   
solder 150       
steel, plain 180       
steel, stainless 720       
tantalum 131       
tin (0 ℃) 115       
titanium (0 ℃) 390       
tungsten 52.8       
uranium (0 ℃) 280       
zinc 59

[K1JJ]

Technically, since SS is 42 times less conductive than copper, to make that SS plate work transparent to equal  copper wire radial-only construction,(no plate at all) each copper wire would need a flange that is 42 times wider than itself to make full contact on the SS plate. So, if a wire is 1/16" in diameter, it would need  42/16ths  or a 2.6" wide copper spade lug to bolt to the SS plate. Otherwise each wire is making a "point" contact with a lossy spot of SS.   Even if the plate were infinitely wide, that rule still exists.

That said, because the current is divided up by all the radials and we are talking only of a fraction of an inch in contact length for the SS after the wide, low-loss plate area, there would be NO measureable practical difference in antenna performance between this SS plate and using all copper.

Still if there were a choice, the copper ring idea with silver solder is an appealing method.


(Why do I even ponder these silly things?)

T

[N6WDR]

Ok you guys changed my mind....  What I will use now is 0/0 copper cable and will silver solder all the radials to it  .  Thank You for all the input.

Richard

[WBear2GCR]

Seems like copper pipe might be more cost effective compared to 0/0 copper wire? Maybe not - and are you talkin' solid or stranded??

                 _-_-bear

[k4kyv]

The cost of the amount of copper needed to make a grounding ring at the  base of a tower would be inconsequential. 3' to 8' would probably be enough.  The main problem would be finding a source that would sell such a short piece, but a scrap piece should not be that hard to find. A friendly electrician would probably give it to you.

I would use solid instead of stranded for the ring, regardless of what I was using for the radials.  Copper tubing would work just as well as solid copper if that's what you can find or have on hand.  

Another idea would be to use 4 pieces of 1/2" copper pipe and 4 copper elbow fittings.  Sweat it together to form a square around the base of the vertical, using the same silver alloy brazing as used to affix the radial wires to the ring.

I made mine in the form of a square from some heavy gauge 1 1/2" wide copper strap that I had salvaged from some rf transformers found at an industrial surplus store.  Probably used in some kind of high power rf induction heating equipment.

                                            ***

According to Tom's chart, silver has the best conductivity (15.9), but just barely a tiny bit better than copper (17.1).  Forget about gold (22.1), except for switch and  relay contacts. Gold is pretty much inert and doesn't oxidise or tarnish, so the contacts would be less likely to become flaky with time. I don't think it would be worth the cost and trouble to silver-plate rf coils. Besides, pure silver is worse about tarnishing and corroding than copper.

The common practice of tinning and nickel plating copper rf coils would seem counter-productive.  Just leave them bare copper.  If corrosion might be a problem in an unheated environment, spray the copper coil with clear lacquer, and periodically touch up any spots that appear to be peeling.

I think the manufacturers of broadcast equipment silver-plate coils just to make them look pretty, and probably to help justify their already inflated costs.

[KA3EKH]

I changed out a high intensity lighting system on a six fifty foot tower a couple years back and that resulted in me getting ten stainless steel light enclosures with lexan windows. Gave several away and trashed some but still have two or three lying around the transmitter site. I wanted to build a base loaded vertical at home with fifty feet of aluminum pipe and a ground radial system for 160 and 80 and use one of the old tower light fixtures to house the base tuning coil and a relay to allow me to remotely change from 160 to 80 but the problem is that the stainless boxes are almost indestructible! I can drill one or two holes in them but then the drill bit is toast, did not try a greenly punch figuring it would break that and when I used a acetylene torch and hit the oxygen nothing happens! You may have a stainless plate but if it's anything like these EG&G fixtures you're going to have some issue drilling holes in it.
Ray Fantini

[N6WDR]

Ray,  Just so you know I went through 5 drill bit's drilling it out lol, funny you would bring that up lol. 

I would have to agree with Don on this one,  I know alot of contractors so I will hit them up and see if I can get some copper tubing from them.

Thanks Again

Richard

[flintstone mop]

Seems like copper pipe might be more cost effective compared to 0/0 copper wire? Maybe not - and are you talkin' solid or stranded??

                 _-_-bear

Hey Bear beings that RF just floats on the "skin" of the conductor the area of the conductor would be better than thinckness. The copper straps 1 inch wide or bigger are better for RF.
Solid copper or stranded wire thickness would be better for 60hz current and DC current capacity.

Fred