I built this Neophyte receiver (QST 2/88)
"Manhattan-style", de N4UY.
Manhattan Neophyte:
I wanted to build a receiver - not a kit, I've done those. I wanted to get as
close to scratch-built as I could - I wanted a companion to my Tuna Tin II. I
can't design my own rigs - I'm a CPA, not an EE. All the electronics I know are
self-taught, so I needed to find an established design that fit my needs. I saw
lots of good-looking circuits in Sprat, QRPp and QST. I decided on the Neophyte
from the February 1988 QST (the article is reprinted in "QRP Classics") for 2
reasons - I could build it for 40m and I could easily obtain the parts. The
Neophyte uses 2 active devises (a NE602N and an LM386), a couple of 10.7-MHz IF
transformers, a 365 pF air variable cap, a little plastic variable cap and the
usual assortment of resistors, capacitors and diodes. I tossed in an additional
25 pF air variable cap because I like controls for both course and fine tuning.
The Neophyte article is available from the ARRL "Merit Badge/Science Fair
Projects" web site at URL:
http://www.arrl.org/tis/info/pdf/28814.pdf
After deciding on the design, I went through 5 basic stages to build my
receiver:
- Obtain the parts,
- Determine the component layout,
- Cut the pads,
- Glue the pads to the board and solder the components to the pads, and
- Test and adjust.
Obtain the Parts
I order my parts from Mouser Electronics. I've found Mouser has most of what
I need, is very reliable and fast. If I have a problem with an order they fix it
quickly. I can order on line and have the parts in a couple days. The Mouser web
site URL is:
Determine the Component Layout
I layout the components to determine how large a piece of PC board to use as
my base and to determine the size of the PC board pads to use to mount the
components. First I look at the schematic and figure out if the controls will
end up where I want them. If they will, then I just layout the components by
following the structure of the schematic. If I don't like the position of the
controls then I redraw the schematic, moving groups of components around to get
things where I want them - I don't redesign the circuit, I just move things
around a bit. Once I have things where I want them, I figure out the base PC
board's dimensions by measuring the size of the components and estimating their
spacing. I make up a rough drawing of the components and pads, cut the base PC
board to size and redraw my sketch on the PC base board. I now have my layout
firmed up, the base cut and my component layout sketched. All I need to do is
cut the pads and start gluing and soldering.
Cutting the Pads
I use different size pads in my Manhattan rigs. If I have a pad with 4 or 5
components going to I will use a big pad. If only 2 components go to a pad, I'll
use a small one (or, if I can get away with it, I'll just solder the components'
leads together). My small pads are about 1/4" square, the big ones might be ½"
by 3/8". I used "L" shaped pads under the Neophyte's transformers. In my Tuna
Tin II I used a long thin 1 1/2" by ¼" pad. I cut my pads with a coping saw and
tin snips - my pads are not pretty, but they work. I don't use little pads to
mount my 8 pin DIPS -- I use one large 1' by ½" pad. I cut 4 grooves in the pad,
1 crosswise and 3 length wise, to divide the pad's copper foil into 8 small
areas (see picture). I then solder an 8-pin DIP socket to my pad and glue the
whole thing to my base board. Its difficult to cut grooves in a 1" by ½" pad -
so I don't. I make up a bunch of DIP pads at once. I'll take a large (maybe 6'
by 6") piece of PC board and layout a row of pads on one edge of the board. I'll
draw a line ½" from the edge of the board, divide that strip into 1" lengths,
clamp the PC board down and then cut all the grooves in the 6 pads. Then I cut
the strip of 6 pads off the larger board and cut the strip into 6 individual DIP
pads.
Gluing and Soldering
Once you have your components, the layout drawn on the base PC board and the
pads, the rest is pretty easy - just start from one end of the schematic and
starts gluing pads and soldering components. I work from left to right, and mark
the components off the schematic as I go to I keep track of what I've installed,
or missed. I count the number of components going to each pad to ensure I use
the right sized pad and that I haven't forgotten to attach something. I put the
pad on the base board, mark the corners of the pad, "super-glue" the pad within
those marks, tin a spot on the pad for each component and then solder the
components to the pad.
Test and Adjust
My Neophyte didn't need much adjustment. I applied power to the rig and got
noise from the speaker. I tuned the input transformer for maximum noise and was
then able to find a 40m signal. I used my big rig to figure out where the signal
was on the band and then adjusted the Neophyte's tuning transformer and the
little plastic varicap the maximize the signals and to get the tuning range I
wanted. I'm happy with my new receiver. It is sensitive and covers the entire
40m band - both cw and phone. I added an active audio filter and LM386 audio amp
- manhattan style, of course -- its at the upper right corner of the enclosure.
I had great fun building the Neophyte -- I'm always amazed at what can be done
with only a handful of components.
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