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Vintage Amateur and Military Radio Amateur/military receivers and transmitters, morse, and any other related vintage comms equipment.

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Old 27th Apr 2018, 4:03 pm   #1
JanWra1
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Default AR88D Transformer cans - material

In an effort to make the interior look a bit cleaner I polished the top o the cans covering the 2nd IF transformer and the Crystal load. They were well covered with black oxidation similar to silverware that had not been cleaned for a long time. After being cleaned the tops looked just like polished silver.
Does anyone of you guys know what material was used? If so please advise.

Jan
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Old 27th Apr 2018, 4:12 pm   #2
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Default Re: AR88D Transformer cans - material

One slight concern with getting it "too" clean would be the tropicalisation coating these receivers received (not all, but many), and potentially cleaning it off.

I've noticed such a coating on mine, and while I did clean the section where some capacitor oil had leaked, I decided to stop because I wondered whether this coating had helped keep it in good condition all these years. Not sure whether that's what you had, mine looked almost light green in places.

'Ill be interested to see what other AR88 fans can offer on this subject, as my receivers need a good clean too
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Old 27th Apr 2018, 5:13 pm   #3
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Default Re: AR88D Transformer cans - material

There seem to have been detail differences in AR88 components over time, I wouldn't be at all surprised if there was hard-eyed thrifting of the production process in many ways as production ramped up sharply with war-time demands, as there was with everything from Jeeps to battleships. I've seen IFT cans that look very much as if they were silver-plated but unpainted, as you say with that characteristic soft black tarnishing that polishes to the typical "champagne" sort of look of silver. It wasn't that unusual for high-quality RF components to be silver-plated for optimum conductivity/Q, though I suspect that there was sometimes an element of lily-guilding and the AR88 was very much an example of putting the effort in where it was worthwhile but not otherwise. Other (later?) IFTs have a pale green outside paint finish with bare copper finish inside.

The elephant in the room with any vintage metalwork is that the plating may be of substances that wouldn't pass muster nowadays- in particular, pale green/yellowy-green tarnishing may indicate the presence of cadmium, which is bad news as far as cleaning is concerned from the point of view of generating poisonous dust.
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Old 27th Apr 2018, 5:41 pm   #4
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Default Re: AR88D Transformer cans - material

The press-on IFT can-covers on my AR88 (an early one, subsequently modified and de-modified for the RAF) are silver-plated Brass. I polished one up once, and lacquered it to preserve the shine!
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Old 27th Apr 2018, 7:46 pm   #5
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Default Re: AR88D Transformer cans - material

Quote:
Originally Posted by turretslug View Post
..in particular, pale green/yellowy-green tarnishing may indicate the presence of cadmium, which is bad news as far as cleaning is concerned from the point of view of generating poisonous dust.
Wow. In terms of potential hazards, these receivers get better and better the more I read

Still, none of it has done me any harm as of yet
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Old 27th Apr 2018, 8:05 pm   #6
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Default Re: AR88D Transformer cans - material

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Originally Posted by PsychMan View Post
Wow. In terms of potential hazards, these receivers get better and better the more I read
Typical of the period.

A lot of Heathkits through the end of the sixties had steel chassis protected by passivated cadmium plating, as did many other things. If you bought posh stuff with aluminium metalwork, that was often protected by 'alochrome' and some proportion of chromium turns hexavalent.... Plastic cases for computer monitors met fire retardant standards with now-banned additives. Dropper resistors sometimes had asbestos cores. Some valves are slightly radioactive. There's beryllium oxide in them thar cellphones.

Some old photoreconnaissance lenses use glasses which are decidedly radioactive, but then some modern camera lenses have glass elements which are very toxic and slightly soluble in water (don't lick them!)

There's nasty stuff all over the place for the unknowing.

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Old 27th Apr 2018, 8:35 pm   #7
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Default Re: AR88D Transformer cans - material

I think it's a case of being careful without being overwhelmed by paranoia- do the initial cleaning/dust clearance outside, and avoid processes that generate too much airborne dust from dulled metal surfaces, such as wire brushing/sanding. Keeping surfaces damp whilst cleaning suppresses dust- after all, that's a large part of what asbestos clearance contractors take care to do and that's very insidious stuff indeed.
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Old 27th Apr 2018, 9:24 pm   #8
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Default Re: AR88D Transformer cans - material

Thanks for your inputs. enclosing 2 pictures showing the top of the IF transformer cans with both polished and non polished.The top of 2nd IFT was polished with metal polish I use on my Norton while the Crystal load top was cleaned with liquid silver clean. The Inside of the tops looks just like the outside.
From the looks of the IF cans, the result of my cleaning and your comments I can only conclude that in my AR88 the material used is silver-plated brass.

As to tropicalisation: It has been treated with something against fungus as can be seen on the 3rd picture - is that what you mean with tropicalisation?

Jan
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Old 28th Apr 2018, 10:41 am   #9
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Default Re: AR88D Transformer cans - material

That looks like silver coated.Think it has been tropicalised.
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Old 28th Apr 2018, 2:09 pm   #10
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Default Re: AR88D Transformer cans - material

Apparently, it was found that electrical and electronic kit in theatres such as the Far East could deteriorate rapidly in hot and humid conditions- compounds like Paxolin and rubber and fabric wire insulation would go mouldy and disintegrate rendering equipment useless, so MFP (mould and fungus protection) was liberally sploshed over many things in the latter part of WW2. Those AR88 chassis shots actually look quite clean, MFP has a characteristic yellow-orange varnish look to it, like an extreme version of nicotine staning, it may be that items like the mains transformer were individually treated at manufacture.

The era, colour and function of MFP suggest that it's likely to have halogenated aromatics as a major constituent- unfortunately, these tend to form nasties like dioxins when in contact with hot metal, so keeping clear of soldering fumes when working on MFP-treated gear is wise. The label talks about cleaning joints before soldering, whether this is for health reasons or simply to stop it contaminating the joint or interfering with fluxing action I'm not sure. When the equipment was made, it might well have been regarded as short-lived and expendable anyway, so long-term maintenance probably wasn't as high on the list as being reliable for a year or two.
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Old 28th Apr 2018, 2:26 pm   #11
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Default Re: AR88D Transformer cans - material

Maybe Moisture (rather than Mould) and Fungus Protection? A bit more (anecdotal) spiel;

http://www.antiqueradios.com/forums/....php?p=1169601
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