2N2/40+
The 2N2/40 was designed by Jim Kortge, K8IQY (I won't go into all
of the detail... you can get tons of information about this awesome rig
on his website). This is
my first scratch built project, and I have to say it was a great learning
experience. If kit building seems just too easy, and you want to
try your hand at scratch building, this is a great one to start with.
There is even a yahoo group set up for hams building this radio.
There are up to date schematics, mods, layouts, photos and lots of other
useful stuff, not to mention all the help from other 2N2/40 builders.
I used it.... it was great. If you want the URL to the group, just
drop me a line and I'll be happy to send it to you.
This radio is built Manhattan style, which is essentially small pieces
of circuit board material "super glued" onto a large piece of circuit board
(5" x 7"). The components are then soldered onto the pads.
Anytime you need a ground... it's right there. More information on
Manhattan construction is available from Chuck Adams', K7QO, website.
Things I did when building the 2N2/40+
The rectangular pads I created for my 2N2/40+ I made using a scroll saw
and a pair of diagonal cutters. Basically, I cut a long piece of
material the width of the pad I wanted, then snipped of small sections
using the diagonal cutters. It seemed to work out fairly well.
One word of caution though. Circuit board material can be very tough
stuff, and scroll saw blades get dull rather quickly. I broke 2 blades
making this rig. If you cut your pads this way, be sure you wear
safety glasses. For that matter... use safety glasses whenever you
are messing around in the workshop... you only have 2 eyes.. and you can't
get them back.
The trickiest thing about building this rig is building the double balanced
mixer. I can't stress enough how much easier it is to identify the
trifilar windings if they are different colors. I got 3 colors of
#28 magnet wire from Dan's
Small Parts and Kits. Very nice for the double balanced mixer.
Don't blow 2 set's of finals like I did. One way I blew a set
was when I was peaking the trimmer caps in the transmitter driver stage.
When you are tuning up that section into your dummy load, make sure you
have the output power turned way down (i.e. most of the power from the driver
stage ends up burning off in the variable resistor).
The other way I blew a set was playing with the transmitt power amp before
I had the heat sinks on the TO-18 finals (yeah... I know).