Eric,
I'm not sure, no, but dip brazing is quite likely the original method of
manufacture, given the colouring of the interfacing between some of the
undamaged filters and the casing. Other (replaced?) filters definitely look
as if they have been soldered, judging from the colouring of those joints.
I have no detailed information on this unit at all (yet), so don't know
what the bushes are made of, or even what they're likely to be made of. I
was given it this morning to assess, to see if we could repair it, so I'm
only at the stage of asking a lot of daft questions.
Where the filters are fitted into the casing there is, surprisingly, no
sign of plating or alchromating, just 'virgin' metal. It may have been
anodised without dying (colouring not expiring), but I don't think so.
Given it's original manufacturer, I suspect it's BS L111 Al.Al. with only
the external surfaces painted black.
Does this narrow the field of thought a bit?
Regards
Pete Duncan
Eric
Christison To: [log in to unmask]
<Eric.Christis cc: (bcc: DUNCAN Peter/Asst Prin Engr/ST Aero/ST Group)
[log in to unmask]> Subject: Re: [TN] Soldering filters to aluminium casing
Sent by:
TechNet
<[log in to unmask]
RG>
07/26/01 04:49
PM
Please respond
to "TechNet
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Please respond
to Eric
Christison
Pete,
Are you sure the bushes aren't dip brazed into the casing?
What are the bushes made from?
Is there any plating on the casing, anodising, alochrome - obviously you'll
have to remove it in the area of the joint.
The alloy composition could be important as some aircraft type alloys
contain unusual alloying elements including copper. Using a disimilar
material to make a joint could lead to galvanic corrosion.
Regards,
>
>
> Hi, T-Nagers,
>
> I have a repair job to evaluate that involves replacing damaged filters
> in
> a 10 year old unit, not of our making. The filters appear to be
shouldered
> with coaxial leads for soldering wires onto. The filters themselves are
> inserted into holes in a machined aluminium alloy casing 3 to 4 mm thick
> until the shoulder butts up against the casing wall. From there, they
> appear to be hand-soldered in place. I have no information concerning
> the
> type of aluminium (if that's relevant), but the solder fillets securing
> the
> filters are well wetted onto the casing wall.
>
> Does anyone have any suggestions about suitable fluxes and solders that
> I
> can use for this job, and whether your choice of flux is water or
> solvent
> soluble?
>
> TIA and best regards
>
Eric Christison
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