[ARC5] Bare Aluminum USN sets.

[Brian Clarke]

Not quite, Mike.

The painted sets' chasses appear to have been spot faced where the serrated 
teeth of the lock washers under the screw heads bit in. But, the serration 
could allow air and moisture to get to the aluminium - so, a small 
electrolytic cell would have been set up, eventually offsetting any 
grounding and hastening what I like to call 'aluminium rusting'.

When I refurbish Command sets, I use some zinc-rich grease over the serrated 
washer to prevent oxidation or the setting up of any electrolytic cell. You 
could use such products as Almanox. Also, use of such grease makes future 
replacement of the potted capacitors, removal of the top and bottom a piece 
of cake - rather than the sheared screws I have often seen. As you probably 
know, drilling out a brass screw from an aluminium 'nut' is not easy. The 
potted capacitors were not so bad as they were generally brass - so, all you 
got was general copper-zinc electrolytic erosion - much easier to refurbish.

73 de Brian, VK2GCE.

On Saturday, October 20, 2012 4:38 PM, Mike Morrow said:


>
>> If the corrosion gets between the potted capacitors and the chassis,
>> the designed RF bypassing is gone and instead you have interstage 
>> coupling.
>
> A "problem" that, one suspects, would likely **not** have been ameliorated
> by paint on the externals of the equipment.  And one that the VHF AN/ARC-5
> units, lacking such paint, seem to have avoided.
>
> 73,
> Mike / KK5F