[ARC5] [Milsurplus] roller inductors

Tue Jan 26 00:38:46 EST 2016

     Brian's suggestion that we all take a short course in electro 
chemistry caused me to do a little searching.  I have not yet found the 
right material but the following might be of some interest:

http://lecturedemos.chem.umass.edu/electrochemistry19_4.html


On 1/25/2016 9:16 PM, Brian wrote:
> Please look up the electro-chemistry of silver. In particular, check 
> the conductivity of silver sulphide - it is a semi-conductor. The myth 
> of silver sulphide being a conductor seems to be promulgated /ad 
> uendum/ by the chemically inert / unsophisticated.  The removal of 
> tetra-ethyl lead from petrol / gasoline has exacerbated the effect of 
> sulphur oxides in the air where there are motor vehicles. Pure 
> gasoline has no sulphur – the refiners add various compounds to 
> promote their vision of economic glory. Silver oxide is almost as good 
> a conductor as silver, but is of a similar colour. Only an analytical 
> metallurgist or chemist can tell you what your specific tarnish is. 
> The point I make is that the amount and kind of tarnish you get will 
> depend on what’s in the air where your equipment resides.
> If your preferred ‘tarnish remover’ can convert silver sulphide back 
> to pure silver and carry off the sulphur, what a lucky person you will 
> be. So will your bank manager. Most ‘tarnish removers’ take away the 
> silver sulphide and leave a larger surface area on the remaining 
> silver – increased porosity – thus increasing susceptibility to 
> air-borne tarnishers. If the silver is a 2 um to 20 um plating, then 
> the tarnish remover may remove the silver completely and irreversibly. 
> Silver sulphide is not the only tarnishing compound. However, proper 
> design of silver-to-silver contacts can wipe away enough silver 
> sulphide and other contaminants to redeem appropriate conductivity. 
> Leaving an oil or grease layer on a roller inductor may protect the 
> untouched underlying silver from air-borne attack. But as soon as you 
> traverse the roller over the wound inductor, you reveal the underlying 
> silver, allowing it to tarnish. This effect can be accelerated by 
> traversing when high current is flowing, giving rise to sparking and 
> formation of contamination. So, tune up at very low power!
> If all you want is a pretty-pretty roller inductor, then by all means 
> polish it till it reflects and then coat it in a transparent varnish – 
> but don’t expect it to work. If, on the other hand, you want your 
> roller inductor to work, then attach a milli-Ohm meter between the 
> roller support axle and one end of the inductor, traverse through the 
> whole range of the inductor – perhaps a few times – observing in 
> detail the resistance vs traverse position. Deal only with places on 
> the inductor or the roller where resistance is unacceptable.
> There is a faint possibility you will be pleasantly surprised.
> 73 de Brian, VK2GCE.
> *On* Tuesday, January 26, 2016 1:14 PM, Bill said:
>
> It should be noted regarding these instructions to “Clean off the 
> oxide” with Deoxit on the roller inductor, that silver tarnish is NOT 
> an oxide, but a Sulfide.  Silver Sulfide is CONDUCTIVE and is not the 
> reason that the contacts are bad somewhere.  Using any cleaner may 
> also remove dirt and other contamination and Deoxit is as good as 
> several others at doing this.  I would use the DL100 Deoxit that does 
> not have a small percent lubricant as does the D5 Deoxit.  It is best 
> to not leave any lubricant or anything at all on the contact.
>
> Many use just lab grade Isopropyl Alcohol for a cleaner.  I use both 
> and they both seem to work equally well.
>
> The following post in the thread after the Deoxit advice that suggest 
> that the problem could be, and probably is, related to the follower 
> spring contact on the contact bar is worth pursuing.
>
> While polishing the heck out of those roller contact areas may make 
> you feel good, and it sure looks nice, it is a fool’s errand for the 
> following reason.  There is Sulphur in the atmosphere..  Some 
> environments have it more than others.  That is why your mother’s 
> Silver tarnishes. When the Silver Sulfide forms, it uses up (eats up) 
> a monolayer or two of Silver. The Silver Sulfide is more or less 
> self-limiting.  Once a layer of the Sulfide forms, it way slows down 
> the process.  When you shine it up, you remove all the Sulfide – which 
> includes that Silver Plate monolayer – and the process starts all over 
> again – at high speed…  and the Silver plating gets thinner and 
> thinner.  This is not desirable.
>
> So, clean all the contaminants off the roller coil with either Deoxit 
> or Isopropyl and then look for the other causes that may be there as 
> suggested.
>
> By the way, do not even think about using Silver Polish..  That is a 
> disaster – especially Tarnex or similar acidic processes.
>
> Bill
>
>
>
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-- 
Richard Knoppow
1oldlens1 at ix.netcom.com
WB6KBL

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