Ground Plane construction vs pre-printed "protoboards"
 

If you want a technique that both looks good and is RF tolerant, try
using double sided board and small pieces of cheap plastic insulation
tape as resist. This applies to through hole parts of course - if you
want to use SM you will have to use dead bug or professionally made
PCBs. You will have to think out your layout carefully before you start
- do this on paper. You can always go back and styart again if it is all
wrong

The board must be scrupulously clean - use steel wool for this and dont
touch with fingers afterwards.

You can do through hole ICs by cutting a matrix of tape from a single
piece on the target board and removing the scrap from beween pads with
fine forceps.

Cut small squares and strips of tape from sections laid out on another
piece of scrap board for traces, resistors, capacitors and transistors.
Cut the tape sections with a sharp blade such as a Stanley knife
Using fine forceps, lift these and place in your desired layout on the
target board as pads and connections on the bottom side. Press down
firmly with another tool to stick

Cover the top completely with tape as a ground plane.

Etch the board in Ferric Chloride.

Remove all the pieces of tape

Drill holes through the pads with a suitable size PCB drill from the
bottom - a small drill press is useful as you will tend to break drills
otherwise

Any pads connected to ground can be left so that the component lead can
be simply soldered to the ground plane, while those that must be
insulated are countersunk carefully on the top side to remove a small
ring of copper - be careful not to drill right through - use a drill at
slow revolutions, or even by hand in a T chuck.

Scrub again with steel wool and spray with PCB lacquer

With practice you can make quite complex boards - I did a complete
triband HF SSB/QRP transceiver using this technique some years ago. I
have used some SM components such as 1206 resistors and capacitors,
combined with through hole parts on occasion.

Richard


Basil B. wrote:
Hello all

I've been doing a fair bit of internet reading about RF construction
projects. I'm still confused about something.

Most authors, including those in the ARRL Handbook, seem to espouse
"ugly construction" and a variant called Manhatten construction. I
understand that the reason is that these techniques minimize
capacitance by providing a large ground plane. Ugly construction seems
to also encompass perfboard construction with wire traces or direct
component-to-component connections. This seems to me to be not much
better than using pre-printed boards whose traces match, in geometry,
those of solderless prototyping boards.

I do understand that the solderless boards are inadequate for RF work,
but are the pre-printed perforated "protoboards" also inadequate.

Call it an OC tendency, but ugly construction is, well, ugly. Of
course, I want to use the best techniques for what I'm doing, and if UC
is the way to go, then that's what I'll do.

I'd appreciate your opinions on this.

Thanks
Basil B.

Ground Plane construction vs pre-printed "protoboards"
 

For years I designed my boards in a time consuming way. I used
Microsoft paint to draw the pattern. I printed this pattern on clear
piece of 3M transparancy using my copy machine at work. Later I used my
home laser printer. I cut and cleaned the board like Richard Hosking
suggested. I then ironed the pattern on the PC board using a home
cloths iron. I used doubled sided PC board. I have always surface
mounted all my parts even leaded types. I used the lower side of the
double sided board as a ground plane drilling holes only to attach
ground leads below. I also placed as much ground plane on the surface
of the board as possible.

This method always worked well but I must qualify my building as being
between 1.8 and 30MHz, nothing higher. In the last 7 or 8 years I have
gone to Ugly construction. I read a quote attributed to W7EL Roy
Lewellen about ugly construction years ago. The method I used was time
consuming. I could save patterns for reuse and dupication but the whole
classic PC board process is time consuming. I tried Roy's suggestion
and never went back to my time consuming process.

My first project years ago was updating a drifty 40M VFO. I measured
the drift in the old VFO to 200 cycle/hr after 20min warmup. The new
VFO using ugly construction measured at 20 per hour after warmup. Both
used the exact same circuit, roughly the same component values but
different manufacturer so the comparison is somewhat flawed. Recent
projects using ugly construction: An new HB RF signal generator, 6W
sideband transceiver, logarithmic RF detector and a 1.7 to 1.85MHz LO
for a new sideband transceiver. This new VFO drifts 10 cycle/hr (47
cycles over 24hr) but is still open to the environment on the
workbench.

I have used ugly construction in tube rigs, VFO's, high gain audio
sections of DC receivers, test gear, etc. The one thing that makes it
appealing is the ability to test a circuit or idea without going into
the long process of PC board prep. The ugly method is intuitive and my
opinion...damn the appearance....does it work well!

Don K5UOS

PS John Miles' receiver is amazing! Wish he lived near me.

Ground Plane construction vs pre-printed "protoboards"
 

Hi Dave,

"Dave Platt" wrote in message
...
One of the recipes for making stable, friendly, and reproducible
designs at RF seems to be to minimize the impact of parasitic
reactances.

Certainly true, although my feeling is that 'ugly' construction above a ground
plane creates _well controlled_ parasitics that tend not to change much based
on, e.g., waving your hand above the PCB, mounting the PCB close to a metal
chassis, etc.

Ground Plane construction vs pre-printed "protoboards"
 

Joel Kolstad wrote:
Hi Dave,

"Dave Platt" wrote in message
...

One of the recipes for making stable, friendly, and reproducible
designs at RF seems to be to minimize the impact of parasitic
reactances.


Certainly true, although my feeling is that 'ugly' construction above a ground
plane creates _well controlled_ parasitics that tend not to change much based
on, e.g., waving your hand above the PCB, mounting the PCB close to a metal
chassis, etc.

My experience is that the most common and troublesome parasitic
reactance in modern solid-state circuitry is, by far, the inductance of
the ground system. And that's just where "ugly" construction shines --
it makes that inductance as small as possible.

Roy Lewallen, W7EL

Ground Plane construction vs pre-printed "protoboards"
 

I tend to use PCBs, but I make them single-sided on double-sided PCB
stock, so that there is a continous ground plane on the top.

Leon