Good point Jim,
I can back you up on the phosphor bronze as a dielectric as it does work
very well. Regarding avoiding the SS hardware path, I have lately been
using AL or CU straps cut from a sheet placed right against the element.
73
Matt
KM5VI
-----Original Message-----
From: TowerTalk [mailto:towertalk-bounces@contesting.com] On Behalf Of Jim
Thomson
Sent: Sunday, March 03, 2019 9:53 PM
To: towertalk@contesting.com
Subject: [TowerTalk] FW: Silver vs Aluminum vs Copper Re: OT: Inductor
Date: Sat, 2 Mar 2019 22:02:56 -0600
From: "Matt" <maflukey@gmail.com>
To: <towertalk@contesting.com>
Subject: [TowerTalk] FW: Silver vs Aluminum vs Copper Re: OT: Inductor
Calculator
<When the surface area of the anode is relatively large compared to the
<cathode, galvanic corrosion is generally not a problem when the stainless
is
<cathodic. Hence using relatively small 18-8 stainless fasteners on
<aluminum elements or galvanized structures generally presents little
<interaction provided that the assembly is not in a salt laden or heavy
<chloride environment. The British Stainless Steel Association has
<published some scholarly articles on this subject as well as NACE.
<I regularly use high chromium stainless washers to isolate copper from
<aluminum or zinc galvanize without issue. A generous application of no-ox
<compound provides added protection and if using stainless threaded
<fasteners, anti-seize compound is a must.
<73
<Matt
<KM5VI
## This is the one thing that Mosely seems to have got correct, they used
Phosphor bonze hardware in several places.
## F12 got it wrong where they used SS machine screws, with double nuts
to make connections
from wire leads from a CM balun to the feedpoint of the DE on the F12
yagis. If they had put the lug
against the bare aluminum DE, then mashed it down with a SS flat washer and
SS nut, all would be ok.
But when the lug is placed between 2 x SS flat washers, with a SS nut on
top, the entire RF current
path is via the SS machine screw...and thats bad news. F12 tried at
one time using 8 gauge solid SS
wire as a hair pin on 40M. Dead center in the SS hairpin, it turned black
! I had the same issue when
terminating cu strap between 2 x SS flat washers and SS nut on a vac
tune cap, doesnt work too good.
Again, the high current RF path flows through the SS machine screw. Since
replaced with silver plated brass hard ware.
On one of the SW broadcast supplier sites, they used phosphor bronze
hardware on everything from
1 kw to 500 kw cxr. Only the size of the hardware changed. Typ
ranging from .25-20 up to 1.0 inch
for phosphor bronze bolts, and mating phosphor bronze washers, nuts etc.
Jim VE7RF
_______________________________________________
_______________________________________________
TowerTalk mailing list
TowerTalk@contesting.com
http://lists.contesting.com/mailman/listinfo/towertalk
---
This email has been checked for viruses by AVG.
https://www.avg.com
_______________________________________________
_______________________________________________
TowerTalk mailing list
TowerTalk@contesting.com
http://lists.contesting.com/mailman/listinfo/towertalk
|