Hello everybody,
I just finished my first homebrew radio, a VHF receiver with PLL, and it's
time to put it in a box ! I've often read that HF circuits should be put in
metal boxes, but I don't know which one should choose. Are "sealed"
enclosures such as this one
http://www.velleman.be/common/produc...?lan=1&id=7318
better than boxes like that one
http://www.velleman.be/common/produc...lan=1&id=11184 ?

And do you think that plastic and ABS boxes are really bad for HF circuits ?

Thanks for your answers !

Hmmmm. I get a "404" at both URL's.

In 22 years of this hobby, RF and audio, I have used every material you
can shake a stick at, even gold.

Plastic, IMO, is for Saran wrap and should stay there ;-)

Wood, tin, copper, brass, aluminum and steel, in that order, are my
personal preferences.

For HF circuits, tin is a superb shield, soft enough to cut with scissors
and easily solderable. As long as your HF circuits are well shielded, the
outer cabinet is restricted only to the materials that will be needed to
withstand the abuse you want to put it through.

--
Gregg
*It's probably useful, even if it can't be SPICE'd*
http://geek.scorpiorising.ca

Damien Teney wrote:

Hello everybody,
I just finished my first homebrew radio, a VHF receiver with PLL, and it's
time to put it in a box ! I've often read that HF circuits should be put in
metal boxes, but I don't know which one should choose. Are "sealed"
enclosures such as this one
http://www.velleman.be/common/produc...?lan=1&id=7318
better than boxes like that one
http://www.velleman.be/common/produc...lan=1&id=11184 ?

And do you think that plastic and ABS boxes are really bad for HF circuits ?

Thanks for your answers !


Enclosures can cost you more than the whole rest of your project if
you're not careful.

The ideal box would be an aluminum or copper box, seamless, with no
holes. This would present problems with controlling your device,
getting power into it and signal out, so you have to make some compromises.

Depending on how sensitive your circuit is and how much RF it generates
you can go everywhere from no enclosure at all to a machined metal box.
For a VHF rig you probably want fairly good shielding.

For enclosures I go to hamfests and garage sales and buy old CB radios.
After I rip the guts out this gives me a good looking enclosure that's
designed for RF and costs way less than what a new one would.

Alternately you can make a really good, ugly enclosure by soldering
sections of unetched circuit board together -- see if there's a surplus
shop in your area that sells the stuff. I mount lids by soldering
sections of 1/8" brass tubing to the inside walls of my enclosure; you
can tap these to 4-40 and run a screw in them. Once you're done making
it work you can put it in a plastic box.

--

Tim Wescott
Wescott Design Services
http://www.wescottdesign.com

"Gregg" wrote in message
news:MsxGc.62277$_5.39830@clgrps13...

Wood, tin, copper, brass, aluminum and steel, in that order, are my
personal preferences.

Let me come up on the other side here. My list would be

plastic, aluminum, wood, copper, brass, tin, steel

OK, I'm lazy. If the circuits are well thought out they rarely need
shielding, and plastic is easy to work, doesn't tarnish, looks decent, and
it's cheap.

Copper tarnishes, steel rusts, and brass and tin are darned near impossible
to get. Wood is a bit of a pain because to get decent strength it needs to
be too thick for many controls. Besides, I'm a terrible carpenter!

The main problem with plastic is that cases of the size you need, whatever
that size is, seem to be hard to find. But with a decent brake, you can get
a sheet of aluminum and make whatever you want. Of course, it's a bunch
more work than just buying a plastic case. But, you get exactly what you
want. I don't think I would actually go out and buy a metal case unless it
was something I considered very important. Getting a case of just the right
size is just as hard as plastic, getting one that looks good even harder,
and it's going to be bloody expensive.

One thing that works well sometimes ... cigar boxes. They are cheap, decent
looking, especially with a little finishing, and come in a wide range of
sizes. The problem is that you need to be careful with circuits that
involve small controls, because of the thickness of the wood. There are
plenty of cigar shops around that sell these things for a decent price.

So mostly I stick with plastic, and use aluminum when I get the urge to bend
some metal.

...

My favorites are cases for HP equipment from the 1970's onward -- I bought
several "broken" HP5328A frequency counters and the modular construction
lends itself well to RF, Test and Audio equipment.

"Damien Teney" wrote in message
...
Hello everybody,
I just finished my first homebrew radio, a VHF receiver with PLL, and it's
time to put it in a box ! I've often read that HF circuits should be put
in
metal boxes, but I don't know which one should choose. Are "sealed"
enclosures such as this one
http://www.velleman.be/common/produc...?lan=1&id=7318
better than boxes like that one
http://www.velleman.be/common/produc...lan=1&id=11184 ?

And do you think that plastic and ABS boxes are really bad for HF circuits
?

Thanks for your answers !

I just finished my first homebrew radio, a VHF receiver with PLL, and it's
time to put it in a box ! I've often read that HF circuits should be put
in
metal boxes, but I don't know which one should choose. Are "sealed"
enclosures such as this one
http://www.velleman.be/common/produc...?lan=1&id=7318
better than boxes like that one
http://www.velleman.be/common/produc...lan=1&id=11184 ?

And do you think that plastic and ABS boxes are really bad for HF circuits
?
===============================
It is difficult to advise on enclosures if the size of the radio and front
panel operating component dimensions are unknown.
However you can readily make your own 'taylor made' enclosures from scrap
(preferably double sided) printed circuit board.
Result : a perfectly screened box with a neat appearance. To prevent the
outside from getting dull due to oxidisation ,it is best to apply a matt
varnish.
Ham fleamarkets are a good source for scrap PCB ,normally sold by weight ,at
least on the european continent.

Frank GM0CSZ / KN6WH

This may be an Urban Legend, but.....

Has anyone ever run into or hear of a situation where a radio "from the
good old days" of steel chassis, would not work when built on an
aluminum chassis?

It has been some time since I heard that, so I do not recall the
details. I suppose it might have something to do with inductance or
magnetic fields???

Curious minds, and all that...

73, Dave - K7HMP

Damien Teney wrote:

Hello everybody,
I just finished my first homebrew radio, a VHF receiver with PLL, and it's
time to put it in a box ! I've often read that HF circuits should be put in
metal boxes, but I don't know which one should choose. Are "sealed"
enclosures such as this one
http://www.velleman.be/common/produc...?lan=1&id=7318
better than boxes like that one
http://www.velleman.be/common/produc...lan=1&id=11184 ?

And do you think that plastic and ABS boxes are really bad for HF circuits ?

Thanks for your answers !