[Amps] Building an Amp 101

[Chris Wilson]

Hello peter,

Friday, January 17, 2014, 5:01:07 PM, you wrote:
> Jerry,

> You do need some tools. An engineers square with ruler, a scriber,
> a centre punch and a hammer, drills - and don't get cheap ones,
> Sears used to and maybe still do some good German ones -  a few good
> new files of various types (flat, warding, half round, rat-tail and
> triangular), a hand drill or maybe big and little ones, and big and
> little hacksaws and a vice - about a 4 inch. Plus some bits of angle
> iron about 3/4 by 3/4 or 1 by 1 inches and 1/8 inch thick, and a
> couple of small carpenters G clamps. A few odd bits of wood come in
> handy, too - short (2 to 3 inch) lengths of 2 by 1. For expendable
> material, you want emery cloth. A small wire brush (barbeque
> cleaning type) is good for keeping the files clean.

> With flat files, you want something like a 10inch bastard cut with
> a safe edge and a smaller 6 inch 2nd cut. The half round and rat tail can be second cut.

> With that lot, you can cut aluminium sheet to size (score a line as
> deep as you can on both sides, clamp it between the angle irons held
> in the vice  with ends of the irons G cramped together, and then
> bend back and forth until breaks. Clean up by putting emery cloth
> flat on the bench and run the sheet edge along until it's clean. Or
> don't score quite so deep, and you can bend it, using the hammer and
> block of wood to square up corners.

> With sheet aluminium and 1/4 by 1/4 by 1/16 aluminium angle stock,
> you can make good enclosures: a cheap pop riveter can ease matters.

> A $40 set of taps and dies from Sear were a good buy for me - from
> 6-32 up to 1/2 inch in fine and coarse thread for the sizes above 1/4 inch.

> Those are the techniques I used before I got my fairly well
> equipped workshop with lathe, mill, shear, metal brake, drill press etc...

> It's worthwhile getting some of the books available on model
> engineering techniques if you have never done a workshop techniques course.

> 'Model Engineering, a foundation course' by Peter Wright, published
> by Nexus Special Interests 1997, ISBN 1-85486-152-2 is good.

> The older (1960s) ARRL handbooks have a lot of good advice on
> workshop techniques, too, under the chapter 'Construction Practises'.

> Good luck

> 73

> Peter G3RZP


I always point people making metal "boxes" to a YouTube video of a guy
with a box pan folder in his (or probably his landlord's) living room.
Proud as punch of his new toy he quickly realizes why it was cheap, as
its throat depth is tiny and seriously hampers making anything bigger
than a hamster's coffin. Folding sheet sharply and shearing it square
are probably the crux of a nice box. You can't beat a 3 foot shear and
a *PROPER* (read probably old) box pan folder. With a box pan folder
comes the need for an array of fingers, either Imperial or metric, and
immediately you are looking at a big investment. Notchers, nibblers
and punches are nice, too. Not saying you can't build a nice cabinet
with basic tools, but realistically unless you actually like
struggling, if you don't have access to some reasonable sheet metal
work tooling, it's better to bite the bullet and buy at least the
basic outer enclosure. Then baffle and divide it to suit your specific
needs. Funnily enough I have just come in from the workshop after
making an antenna switching relay box. If I was honest with costing my
time, buying something would have been cheaper, but it is a hobby at
the end of the day, and I could at least tailor it to my exact needs.


For sure, a separate enclosure for the HV supply is sensible,
especially if you build something that suits a family of valves, as it
will do duty for several amps.







-- 
Best regards,
 Chris                            mailto:chris at chriswilson.tv