For the all transistor transceiver group.
You will need to match crystals.? Here is one option of many.
Go to W7ZOI.net and go to the technical stuff button top right.
At the bottom of the new page is a section labeled filter design
and crystal things.? Top of the list is "9 MHz Filters with
Inexpensive Crystals".? There is a Colpitts Oscillator in Fig 3.
First photo below is my build using Manhattan Construction.? I'm
a bit rusty and some things I forgot.? 1.? I hate Rustoleum with
a passion.? It is a very very good paint.? That is the problem.
Used clear matte on the base board.? It just won't melt with the
soldering iron.? I'm going to drive miles to find a can of Krylon
for any other boards in the future.? 2.? Use an IC socket cut to
three pins for interchanging parts.? The 2.54 headers work, but
sometimes flaky.? 3.? Use the 2.54mm vector board to get pins
to 2.54mm spacing, like some preformed legs from manufacturers,
for ease of changing in and out.
I changed the 47 ohm resistor to 10K to drop the voltage on the
collectors of the transistors to around 8V.? Second photo shows
4MHz crystal output with the circuit.? That is the frequency
the counter showed for a whole hour.? Not a Hz shift at all.
Reasons.? Room temp never changed.? We used crystals on HP projects
for thermometers back in the day.? With the lower voltages there
is less heating of the crystal, thus no drift.
Note the sockets for the transistors.? Tried 2N2222s from the 840
pack (third figure) and the 2N3904.? The 2N2222 does not work.
The 2N3904 does.? I tried a stray 2N4401 in a small plastic
container of random parts and it works.? This for the 4.000MHz
crystal.? No joy for 9.0000MHz crystals.? This due to the 470pF
caps being too large.? See specs for other crystal checkers.
Here are the h_fe figures for the three transistors.? This done with
the Chinese Critter Checker.
2N2222? h_fe = 288
2N3904? h_fe = 359
2N4401? h_fe = 439
You can see why I prefer the 2N4401, even though a number of sites
show them as interchanging parts.? There are plus and miuses in life.
This checker to be used later (with mods).? If you don't have a freq counter,
possibly an SDR.? General coverage receiver with SSB/CW capability.
Use fixed dial setting and match tones of the crystals.? Closer than
a random selection.
I recommend, for all new Manhattan builders, to try this out.? It will get
you started.? IMHO.
FYI and thank you for your time,
chuck
OH.? For the 840 pack of transistors.? You can throw the chart out.? It is
an Easter egg hunt for the right parts.? Some one has a sense of humor at
the assembly line.
