Topband: 80m rotatable dipole load coil questions

[Wes Stewart]

I am familiar with Alodine.  It was used by the 100s of gallons of the liquid 
version to passivate the aluminum in the products produced by my former employer.

We also had the facilities to do this and other plating in our engineering 
shop.  You can see some of my personal handiwork here: http://sadxa.org/n7ws.html

I can tell you that the "conductive" version isn't at 10 GHz.  The prototype 
Phoenix missile solid-state amplifier that I was responsible for getting from 
prototype to production used an aluminum cavity with sixteen IMPATT diodes 
arrayed radially around the cavity.  The cavity was machined into one piece of 
passivated aluminum that was closed with another.  The power out and tuning was 
very erratic and could be changed by separating the parts, cleaning the surfaces 
with swabs and alcohol and reassembling them. We finally gave up and went to 
gold plating.  Problem solved.

This is far enough OT that I won't elaborate on another example where gold 
plating can get you in trouble.

On 10/12/2016 3:51 AM, David Cutter wrote:
> A quick note on  a protective coating for aluminium:
>
> You might like to look at Alocrom 1200 (Alodine 1200 outside Europe) which can 
> be  hand-applied to preserve and protect aluminium from corrosion, retaining 
> its conductivity.  I used it for many years in industrial and military 
> applications, where it is applied more thickly but for our purposes it 
> produces a pleasant gold colour.   You can mix small amounts for small areas 
> that need protection.  Surfaces need to be scrupulously clean first.
> Over here a 1kg kit can be purchased for around £40 including delivery.
> https://www.silmid.com/products/alo1200po1-bonderite-alocrom-1200-powder-brush-kit.aspx 
>
> Here's the instruction leaflet:
> https://www.silmid.com/MetaFiles/Silmid/1a/1a5a6311-ae94-457b-a635-93c06b3121bc.pdf 
>
>
> David, G3UNA