On 1/17/2014 10:10 AM, Jerry wrote:
I have had a long desire to build my own linear HF or VHF amp. I believe I
have the electronic technical skills but after looking at some completed
projects like those on WD7S website, I realized I don't have the skills or
tools to do a nice job on the mechanical aspects of chassis / sub-chassis
sheetmetal work. I guess I could cram it all into an unattractive box
behind a reasonable looking front panel but is linear amp building mainly
for those with good metal work capabilities? How does one break into this
with limited workbench space other than an electronic workbench?
There are some links to very well laid out amps on here but no one will
mistake them for commercial built amps.
Starting with the front panel, there are places that will produce a
commercial looking panel at a reasonable cost. Not cheap, but what I
would call reasonable. They have a soft ware program that lets you lay
out the panel, send it back to them and they will produce the panel.
I've done a lot of construction, but I've never been able to use a saw
and drill to produce professional looking results.
For cabinet work, I'd get a metal brake. They are not expensive items
for something rated to work with the Aluminum used in chassis work, but
again they aren't cheap. Look at www.grizzly.com . They have small ones,
but it depends on how large a piece you want to bend or cut. Prices go
up rapidly with size and can easily cost as much as an amp... or more<:-))
Metal brakes that will handle chassis work are relatively easy to build
out of steel angle and a rod or pipe to give you leverage. It does take
a bit of thought and planning when bending your own to get the
dimensions correct. The biggest problem is getting a smooth surface on
the angle that you then polish if you want scratch free results. The
only tools needed to build one are a hack saw and a drill. Look at the
designs of the vise brake. If you have a large and heavy vise mounted
on a heavy bench (as in welding bench) you can clamp two steel angles
for the one side and use "C-clamps farther out. You are still going to
be limited to not much more than 12" in most cases. Don't make one an
inch larger than what you will need as they are heavy and going larger
means thicker steel. They can be designed to mount using "C-clamps" on
a "STRONG and RIGID" work bench. With a frame that bolts to the floor
they are really heavy.
In the end, most hams will use angle and flat sheets which immediately
says home brew, but it's so much easier and faster. Plus you don't have
to take into account the metal thickness as you do when bending the
material. Just learning how to bend flat stock and come out with the
correct dimensions is an art. IOW You have to tell the supplier the
dimensions of the sheet so it will have the proper dimensions after
bending. Just making two bends in 1/16th sheet can have you off by an
1/8th inch or more. It all depends on how much of a perfectionist you are.
The shear would be difficult, or impossible for most to build and as the
metal suppliers will usually cut the material for little or even no
cost, it's hardly worth the effort and certainly not the cost. If you
can find the blades of the appropriate size and reasonable price it
would simplify building one, but the forces are such that one even for
cutting chassis material can be massive and require a tremendous force
to do the cutting. Still, having the supplier do the cutting makes the
most sense unless you plan on doing a lot of metal work.
73,
Roger (K8RI)
Jerry
_______________________________________________
Amps mailing list
Amps@contesting.com
http://lists.contesting.com/mailman/listinfo/amps
---
This email is free from viruses and malware because avast! Antivirus protection
is active.
http://www.avast.com
_______________________________________________
Amps mailing list
Amps@contesting.com
http://lists.contesting.com/mailman/listinfo/amps
|