[ARC5] BC-AN-229 Follies, part 2

[WA5CAB--- via ARC5]

The problem with the propane torch is that if the can is oil-filled, you 
will quickly have a fire on your hands.  I use a 200 watt American Beauty with 
a chisel tip just under 3/4" dia.  With it, I have done a bunch of the 
rectangular can types that are found in the BC-312 family.  I've forgotten 
exactly how the ones in the GR/RU and SCR-183/283 family are constructed.  But on 
the ones I have done, I remove the top, not the bottom.  Then when the can 
has cooled, invert it to dump out the oil and then leave it inverted for a 
few hours to let the remainder of the oil drip out.  Then I use a 40 watt 
Weller and a Pace desoldering handpiece to remove the individula capacitors.  
I'm afraid that if I heated and removed the bottom with capacitors still 
attached, the heat would ruin the feedthroughs and seals.  Plus, if the unit has 
one side of the capacitor grounded, the ground lead is captured by the lip 
of the top and you wouldn't be able to smoothly lift off the bottom from the 
can because the other end of the capacitor(s) is still attached to the can. 
 Removing the top first, there are no wires to deal with during the messy 
hot part of the job.

Two more comments - it's much easier if you remove the cans from the radio 
first, although I did do two without doing that.  And put the vise holding 
the can in a shallow rectangular (cake) pan, especially if you have a wooden 
work bench.

Robert Downs - Houston
wa5cab dot com (Web Store)
MVPA 9480

In a message dated 11/15/2014 16:52:59 PM Central Standard Time, 
kgordon2006 at frontier.com writes: 
> On 15 Nov 2014 at 17:05, Tim Des wrote:
> 
> >On *Sat Nov 15 15:23:13 EST 2014, Neil said...*
> >
> >  Heat around the soldered perimeter with a propane gas torch, brushing
> >away the melted solder and paint with a wire brush. Don't linger too long 
> with
> >the flame in one area. When all the solder/paint are gone, pull upwards 
> on 
> >the handle. If part of the can refuses to budge, play the torch on that 
> area
> >and keep scrubbing it until the base and internals can be lifted out.
> >
> >We used to do that several times a week with delicate assemblies that
> >included crystal filters.
> 
> I have used Niel's method with several Heathkit crystal-filter cans and 
> have 
> never (yet) had a problem.
> 
> I cannot imagine that this method would NOT work with those "bath-tub" 
> caps.
> 
> After all, they were soldered together when they were made, and I can see 
> nothing wrong with using the same method to take them apart.
> 
> FYI, the soldering irons that were used back then were usually large 
> "soldering coppers" which were heated with a torch. I believe those were 
> still 
> being used by those who make or repair gutters, and also plumbers used 
> them, up until quite recently.
> 
> Those usually had a large "head" made of a solid block of copper, a fairly 
> 
> long rod which connected that head to the wooden handle, which was itself 
> fairly thick to prevent the heat from the copper making the handle too hot 
> to 
> hold.
> 
> The copper head usually weighed at least 2 lbs, was usually at least 4" 
> long, 
> and about 1" to 1.5" square with the "far" end filed to a point like a 4 
> sided-pyramid. They were equivalent to about a 500 watt iron.
> 
> I know OTs who used those things to build radios with...
> 
> Ken W7EKB
>