Cheap Stainless-Steel Radial Plates

Being a ver­ti­cal afi­ciona­do, I lust over man­u­fac­tur­ers radi­al plates pop­ping up. Too rich for my blood, how­ev­er, at $50 a pop. I read a recent QST Hints and Kinks col­umn where some­one decid­ed to use a stain­less drain insert and I my mind start­ed racing.

Stain­less over Alu­minum? Yes. W8JI states what is most impor­tant is to min­i­mize resis­tance in the ground sys­tem. Any method tak­en one needs to guard against the for­ma­tion of oxides to lim­it resis­tance and “diode-effect”. I picked stain­less steel, while exhibit­ing slight­ly infe­ri­or con­duc­tiv­i­ty to alu­minum, to lim­it the amount of main­te­nance required.

Rather than sol­der, I intend cre­at­ing oxy­gen-free mechan­i­cal con­nec­tions to hold cop­per-lugged radi­als to the radi­al plates. There are con­duc­tive greas­es avail­able specif­i­cal­ly for­mu­lat­ed for cop­per-to-stain­less con­nec­tions. I will sol­der the radi­al wires to crimped lugs, how­ev­er, most­ly to pro­tect and fill any mechan­i­cal voids between wire and crimped con­nec­tor to pro­tect against weath­er. I will be using sil­ver sol­der for this job.

Why not use an even cheap­er heavy cop­per wire buss and sil­ver-sol­der radi­als to it? First, I will be adding in stages, and do not want to risk undo­ing what I have already sol­dered. A cop­per buss also becomes very rigid, and I want some flex­i­bil­i­ty in order to move things around with­out too much trou­ble. Also, my wire choice can be any­thing from sur­plus com­put­er cabling to flex-weave spool ends. It is eas­i­er to use lugs to make attach­ment to the radi­al sys­tem due to the dis­sim­i­lar wire types.

Hard­ware store crawl: Found sev­er­al stain­less steel drain inserts – one heavy gauge and one lighter. Each had holes that fit at 10 – 24 stain­less-steel pan-head machine screw, and could accom­mo­date 8 – 15 screws and there­fore 8 – 15 radi­als each, or 20 – 30 each if I dou­bled them up which is intend­ed. I removed the cen­ter posts from each of the drain inserts…not needed.

For hard­ware I select­ed packs of 10 – 24 12 inch machine screws, along with mat­ing lock nuts with nylon inserts. Split-ring and reg­u­lar #10 stain­less wash­ers make up for each screw. Bolt goes through the “under-side” of drain insert (I flipped it upside down so it is domed rather than cupped) with split wash­er between screw-head and drain insert. The oth­er side I place a SS flat wash­er and lock nut. I may decide on a split-wash­er as well on top depend­ing on how well every­thing holds. Pic­tures to fol­low soon. All told this sys­tem has cost me about $15 total. Each one of these will be attached to the base of my ver­ti­cal by a short piece of heavy cop­per. One sys­tem will serve as the attach­ment point for south-bound radi­als, the oth­er for north-bound.

I won­der about the dura­bil­i­ty and fin­ish of the lighter gauge sink insert. Peri­od­ic checks this win­ter will pro­vide the answers. In the mean­time, I will have cre­at­ed a radi­al attach­ment sys­tem much more flex­i­ble for my use and at a quar­ter of the cost.