In 1997, the Northern California QRP Club sponsored a design contest, which K8IQY won with this design. Jim designed his transceiver using the clubs contest rules which restricted him to using only 2N2222 transistors. Not only did he have to use only the 2N2222 transistor, he could only use 22 of them, hence the name of the transceiver. The "40" in the title indicates the band it operates on, 40 meters in this case. The transceiver has undergone many improvements since it first appeared in 1997. I am building the 2N2222-40+, which is the latest version.

If you are interested in building one of these rigs, there is a Yahoo group, with over 200 members. Most all the documentation you will need to complete the transceivers can be found there. Jim, K8IQY. has a web site as well that has lots of good information on it

Jim suggests that you start out building the RX/TX driver circuit as it is the least complicated circuit in the transceiver. Because there are several versions of this xcvr out there, make sure you build the rig using schematics with the same date. I got off to a shaky start trying to get the RX/TX circuit to operate properly. Come to find out, I was using an older checkout procedure and the circuit was working just fine. Jim is always willing to help trouble shoot any problems you may run into. The Yahoo group is another great resource.

RX/TX Driver

As you can see, there isn't much to the RX/TX driver circuit. The entire transceiver is build using round pads glued to a 5X7 copper circuit board. This building style is referred to as "Manhattan" style. There are a couple of good web sites that have suggestions using this style of building. Do a search for Manhattan on the web and I'm sure you will come up with it. If you visit the 2N22-40 Yahoo group you can find photos of rigs that others have built. Although I'm trying to make my look as good as possible, I just can't compare to some of those. One thing though, the circuit looks much better "live" because these close up photos show up every little mistake.

The next section built is the VFO. Below is a view as seen from the top of the VFO. This part of the transceiver is a bit more complicated. I had been reluctant to apply power to the circuit for fear it wouldn't work properly. My fears were unfounded as the VFO took off with only one small problem and that being the frequency spread of the VFO. It should tune 2085 - 2185 mhz but I am getting 2060 - 2170 mhz. I haven't tried to figure out how to increase the spread as yet. I plan to continue on with the next phase of the rig and I'm hoping for as much success with it.

 

TC3 was added after this picture was taken.

This is my favorite shot of the VFO, you can see the RX/TX in the background.

This is a side view of the VFO.

The next section built should be the RX RF pre amp/mixer. I just finished this part up and have not applied power as yet. Below are a couple of views of this circuit.

 

The picture below is the way the transceiver looks up to this point in the build.

Once I finished up the RX/TX pre amp, I just kept on building, it's just too much fun to stop at this point. I continued on with the crystal filter and finished that up in a couple of hours. Here are a couple of shots of the crystal filter.

On to the next stage, the receiver local oscillator. This is another easy build as there aren't very many components in this section. Here are a couple of shots of the RX Lo.

Now on to the final stage of the receiver portion of the 2n22-40+, the RX mute/audio amp. I don't know if I will be able to mount the audio transformer in this section. I left a little too much room in the upper part of the layout. I may just mount it on the front of the board and let it hang over just a little, it all depends on the room I have in the box I'm using. I can always mount the transformer on the side of the box, so it isn't a big problem. Here are a couple of shots of the audio section. In the one on the right you see the audio transformer sitting in the only place it may fit. It will be tight but I may try it anyway.

Here is a overall view of the transceiver up to this point. The empty space in the center of the board is where the transmitter portion of the transceiver will go.

I started checking out the receiver portion of the 2N22-40+ but have run into some problems getting it to work. I'm not sure what is going on but the waveforms I see at different points in the receiver chain look distorted. I believe this is being caused by unwanted oscillations somewhere in the early stages of the receiver. On the positive side the audio section seems to be working because I can hear the oscillations in the speaker. I'm not much of a technician so I'm stumbling around at this point hoping to discover the problem. Since the transmitter section is the next section to be built I will go ahead with that and continue looking for the receiver problem. Here are a couple of waveforms taken as indicated.

This was taken at the VFO RX output, before it was connected to T4 it looks normal to me.

This picture was taken where the VFO is connected to T4, I'm not sure why it looks distorted.

UPDATE: These distorted scope presentations were caused by unwanted oscillations in Q4, caused by the one turn link on T6 being phased wrong. I reversed the turn and everything looked normal

This picture is the waveform taken at the collector of Q4. Q4 is working because there is a large increase in the signal at this point.

After talking with Jim, K8IQY the designer of the xcvr, I decided to rebuild T6. Below are pictures of T6 after it was re-done. You will notice that T6 is now standing upright rather than lying flat on the PC board. I put the pictures here so that Jim could take a look at them and see if he can spot anything wrong.

After many hours of troubleshooting and emails to Jim, I discovered that I was misreading my scope. Instead of 3V P-P from the the VFO I was only getting 1.5V P-P. This was not enough voltage to drive the DBM. To correct the low output, C12 needed to be changed to a larger value. I didn't have the correct value in my junk box but I was able to use three different values to come up with a cap in the neighborhood of 390pf, which gave me 4V P-P. After installing this make shift capacitor I applied power to the transceiver, turned the tuning pot and I was hearing CW. I touched up TC9, the antenna cap, TC1 and TC2 and I'm receiving good strong signals. Even though the receiver wasn't working, I couldn't resist continuing the build. This decision worked in my favor because the remainder of the receiver and audio section was completed I was able to tune up the receiver without having to use a general coverage receiver.

Below is a picture of the transmitter local oscillator/driver section, as you can see I was able to put the audio transformer in this section without too much difficulty.

 

And here is a picture of the entire board up through the transmitter local oscillator/driver. I will dress up the wires after everything is working properly.

I finished up the transceiver and now it was time to see if I am able to get the transmitter portion to output some RF. Below is a picture of the finished board.

Well, not too surprising, just my luck nothing on the watt meter. I was disappointed but not defeated. I started checking for correct components and improper solder joints. I found one resistor that I had not solder to it's pad. That has to be the problem! Nope still nothing, but I can hear the driver on the Elecraft K2 so at least that is working. I fired up the scope and see that I'm not getting much in the way of drive, back to checking the circuit. When I didn't have enough drive from the VFO I had to increase the capacitance in one of the tuned circuits so that is where I started looking. Whoa! what is that .01pf cap doing there? That should be a 120pf. Change the cap to the correct value and I'm getting just over 2 watts out, into a dummy load, whew! It works! Now to start working on the case. It took a couple of afternoons to drill, paint and label the case. Below are a few of pictures of the finished product.

I need better photo lighting the labeling is much darker than the picture shows.

 

I wanted a way to determine what frequency I was on so I added a Small Wonder Labs Freq Mite to the rig. The Freq Mite seems to work well and for $20 it is well worth the cost. This was such a fun project I am waiting with great anticipation the arrival of the 2N2-20, which Jim is working on. Jim will probably have the prototype with him at Pacificon this year (2004). I plan to make at least one day of the convention and look forward to meeting Jim in person. I haven't made a real contact with the 2N2-40 yet but not because I haven't tried. I did a local over-the-air test with Gary, N6DZA and he said it sounded good. Now that the rig is completed......what am I going to do with all my spare time? Thanks Jim, it has been fun!

 

 

 

 

Back