Amateur Radio Station KG4IGC

Summerville, South Carolina EM93va

My QRP Projects



For the past couple of years, I have been getting more and more interested in QRP operation.  I cannot even begin to express how much fun that I have had learning by building my own QRP equipment and accessories.  It is truly a blast.  I only have a very small amount of projects that I have built but I plan on sharing them with anyone who is interested.  As I said before, I am just a beginner at electronics, but man, I gotta tell you, it is a fascinating hobby.  My plan of action in the immediate future is to learn by doing so this page will evolve project by project and will contain anything that I do QRP.  I know that for the some of the old timers allot of this stuff that I post might be Ho Hum because they have built so much stuff over the years.  My hopes are  that my projects and comments might help someone who is in the same boat as me, a newbie. Thanks for stopping by, hope that you enjoy the page. Check back from time to time to see my latest and greatest projects!


Another Small Wonders Project...the Rockmite 20




June 2013

I got the builders bug again and decided that I wanted another go at building another Rockmite CW QRP transceiver. I figured, well, I already built the Rockmite 40, why not make one for twenty meters as well? I went ahead and ordered the kit, along with the accessory kit (which is of course, optional, but necessary) and it arrived a few days later in my mailbox.I took inventory and sorted out the parts to get them ready for assembly, which is a habit of mine. It just makes it so much easier to put together when things are sorted out.






I figured that this would be an easy project since I had already built the Rockmite 40, and for the most part it was. I assembled the entire kit, got my Altoids tin and made the necessary holes for the accessories. Because of the fact that I was using a tin that did not have one of the nice pictures on it, I decide to take the time to paint it. After putting  a nice coat of primer on it, I got into my wife's acrylics and painted it aqua blue. I wanted a textured look to the finish so I dabbed the paint on with a small paintbrush as opposed to brushing. The results were well to my liking and I finished it off with a few coats of the XYL's nail polish to make it shine. To see my finished kit,click here...

Once the tin was ready, I installed the accessories.
I felt confident enough to go ahead and install the circuit board, after all I HAD followed the building instructions to a tee...or so I thought. I seemed to have missed the part where the instructions specifically tells you to test the thing out before you go through the trouble of installing it in its enclosure. I did hear sound when I put DC voltage to it, so I figured that the build was a success. Boy, was I wrong. I noticed right away that something was not right with the switch that controls the character speed and does the 700 Hz shift.

When I held in the button, I got the three dits and one single dit, so I was able to speed up the keyer and slow it down. The problem was that
when I tap the button, nothing seem to happen. You are supposed hear a noticeable change in frequency through the headphones whenever you tap the button. For some unknown reason, the frequency was not shifting like it was supposed to. I  went through the trouble shooting guide in the supplement instructions and everything it recommended checked out like it was supposed to voltage wise. I then checked for solder bridges and of course, did not find any. In a last ditch effort, I  reheated all my solder joints to ensure that there was no cold solder joints. Naturally, after all my efforts to track down the problem, the thing still did not work right.
I tried posting my problem on some newsgroups and It was first suggested to me that  there could be a short either in the wiring to the push button or the key jack or one of them may be defective. Some initial checks proved that theory not to be what was causing the problem.


After exhausting all of my trouble shooting efforts, I turned to the QRZ forums
and enlisted the help of
Chuck Carpenter, W5USJ. After doing several voltage measurements on U3,R9,D5,R10,Q2, and D6 it was suspected that D5 might be bad. I pulled the diode and checked it with my ohm meter on the diode setting and it checked out fine. I then checked the voltage on D5s pads on the board and measured 0.0 and 0.8V. Chuck had told me that without the zener the voltage will be close to the supply voltage. Since the diode was OK, and the voltage measurements were wrong the only thing left was Q2, which in the end, turned out to be bad. Once replaced with a new one, the frequency shifted like it should when the switch was pushed.

This project turned out to be very challenging for me, to say the least.  I have to say that without Chucks help, I would have been lost. It is nice to know that there are folks out there that will take the time to help you when you have a problem with a project. Chuck was very patient with me and took the time to explain how the circuit should work in elementary terms that I could understand. His careful explanations went a long way toward helping me understand how that circuit was supposed to work. Thanks to him, I not only have a working rig, I have a better understanding
what was causing my Rockmite to malfunction.







                         
My Heathkit HW-7 and our latest shelter rescue kitty Mystic

I have been toying with QRP for a number of years in various modes using the big rigs but this  was my first attempt at trying QRP at a whole new level, the world below 5 watts. I bought this HW-7 at the Charleston Hamfest a few years back, with the full intention of making tons of QRP CW contacts...unfortunately, I only made a few contacts here and there before the sunspot cycle went kaput. I continued to try to make contacts using random pieces of wire, my homebrew mobile "bug catcher" and other various compromised antennas with little or no luck.  This rig was in good working order when I bought it, but now has some issues thanks to me. I used to take this rig to work with me and set it up during my breaks or after work because I was more out in the country and had allot less noise. One day, I was in a hurry to set it up and managed to hook the DC power up backwards. Nothing happened until I turned on the power ... I knew immediately what was wrong when not even 2 second after powering up I started to smell that distinct burning smell. Talk about someone getting upset really quickly! I immediately powered down and yanked the wires leading to the battery while spewing all sorts of profanity but the damage was done. When I got home, I opened up the case and to my surprise, nothing looked destroyed. You could still smell the burnt components though so I figured that something had to be damaged. I powered the rig up again (making sure that the polarity was right this time) and it came to life, I was able to hear stations and I was still able to transmit. I started to think that I must have got lucky by cutting the thing off quickly, so I put it back together and shelved the thing. Time passed and I decided to give the  HW-7 another try, this time in the back yard. I got everything set up, and tried for a couple of hours to make a contact without even a nibble. Of course, my thoughts went back to the day that I "let the smoke out" and decided to try and hear myself on another rig. When I brought it inside to the shack, I noticed that I could no longer tune the rig to its rated 5 watt anymore and upon listening to my transmitted signal, I sounded REALLY bad on the air. Not knowing how to troubleshoot the problem, I turned to the online message boards for help. My plea was answered by Phil, k4dpk and he suggested that I check Q1, Q2, Q3, and  Q12.  Due to fear of diving into this thing alone and other projects getting in the way, I have yet to get involved with fixing this rig as of yet. I have, however, been eyeballing it recently and think that perhaps I might be ready to take a shot at fixing it. One thing that I know for sure that I will be doing is putting a protection diode in it. Anyone who has any other suggestions of what I might look at please feel free to comment. My email is kg4igc[email protected] or you can post a comment on my guest page.

UPDATE:  Alex KR1ST came to my rescue and offered to take a look at it, and found a couple of problems. It seems that Q6 and Q7 were shot and I needed replacements. Fortunately, I have tons of parts in the junk box and was able to produce a couple of 2N2219s which worked just fine. RFC2 was burnt as well, and of course, I couldn't find a replacement so Alex put two coils together and got the correct inductance needed. He also wound up replacing the 15 meter driver pad because it would not work correctly when realigning the rig. My replacement was a little bigger than the original. Naturally, it does not want to fit in the space provided so now it sits a little cockeyed. Initial testing shows that the transmit power is a little low, about three watts output, and the rig is once again functioning like it should. After I got the HW-7 back, I took the precaution of installing a diode in line with the +13DCV, now hopefully the smoke will stay in the rig!  For those of you that don't know how to do this, it is very easy. You can use a silicon diode such as the 4000 series. A 1N4001, 1N4003, or 4007 would work just fine. It is connected in line with the positive power lead to the rig. The anode will connect to the power source, and the cathode to the rig. The cathode is the end of the diode that has the line around the body. That end goes toward the circuit board. The diode will only allow current to flow if the anode is at a more positive voltage than the cathode.In other words, there will only be power to your rig if you connect the positive lead to the anode.

06/04/2012

12K5 12 Volt Vacuum Tube QRP 40 Meter Oscillator




One afternoon I was looking Ebay for kits when I came across this little gem. It is a very simple one tube oscillator that runs off of 12 volts. I have always wanted to build something "tube" that was geared toward a beginner, so I broke down and ordered one from the seller. I did not have to wait long, I think that it only took about three days for it to arrive. I remember reading about this kit  a few years ago in CQ magazine and wanting to build it back then. Somehow that never happened so I was glad to get this opportunity to build one. You can order one from Pastime Projects  for a reasonable price along with some other really cool projects to select from.

 
 The kit comes with everything needed to build the oscillator including the 12K5 "space charge" tube. After parting everything out, I could see that this was going to be an easy project. The instructions were very clear and easy to understand, and I had the kit built in two short afternoons. I found that I did have to drill holes (of which were clearly marked) in the block of wood supplied to mount the components. This is highly recommended to avoid splitting the wood. The hardest part of this kit was putting together the tube socket, of which all of the components eventually connect to. The coil was prewound, so that made things even easier to assemble. There is an extra coil form included in the kit if you want to experiment with another band, but the 40 meter coil will have to be desoldered to do that. I was a little disappointed that the crystal did not fit in the ceramic holder, so I found an old JAN crystal that had adapters that I could reuse. After removing them fom the old crystal, I soldered them to the one supplied with the kit. Once solderered, my crystal plugged right into the ceramic holder.
 
 
 
When I finished building the kit,  I made a little dummy load out of some quarter watt resistors and hooked it up to my 12VDC power supply. I used my Yaesu FT-1000MP Mark V Field as the receiver and proceeded to tune the rig via the small tuning capacitor on the front of the rig. Basically, I tuned it for the strongest signal on the Mark V and zero beated the signal on 7.040. The output power for this rig is very low, probably somewhere around a few milliwatts, but I really can't say as I have no means to measure output power that low. I tried using my RF probe with a DC voltmeter, and I found that I was getting too low of a voltage (.08VDC) for the 1N34A diode in the probe which requires .25VDC in order to get a more accurate reading on my voltmeter. 
 
 
 
Despite not being able to measure the output power, I removed my dummy load and hooked up a tuner to my oscillator and my 272 foot horizontal loop. I did manage to make a contact with another ham in Pennsylvania, but it took considerable effort. The contact was made around 2 AM with QRN and QSB, so a set of really good ears was needed to hear my little peanut whistle.  As you can imagine, I was pleased as punch with the contact and now am awaiting conformation of QSO. If you would like to hear what I sounded like in Pennsylvania to the other QRP operator, click here.. Overall, I was really pleased with this kit and am having allot of fun with it. In the future, I might take it and a battery to a park or something and hook it up to my quarter wave vertical  just to see what kind of results I will get. To see more pictures of this project in various stages of being built, click here...
 
 

10/07/2010

Rockmite 40 Meter QRP Transceiver.

 




Back in December 2009 I got the "builders bug" in me again so I started looking for an affordable QRP  CW transceiver.  I decided on the Rockmite 40 meter and placed my order online via their web site. The kit looked fairly simple to build from the website and being a newbie at building stuff, this kit was right up my alley. I was very pleased with the service that I received as well as the kit itself when it arrived here about a week later. I do have to admit, when the envelope arrived, and I eagerly opened the package I was a little intimidated by its contents. All I saw was a whole lot of little parts and a couple of pieces of paper for instructions and a schematic. Where was the Heathkit builders manual that was supposed to come with it ??

 As I said, I am rather new at building kits and don't build them often enough to feel comfortable without a good detailed set of instructions. Well, after I got over my initial fears I actually took the time to read the material that came with the kit.  You, know, sometimes that really helps....I saw that there was a down-loadable PDF file with more detailed instructions and between the both the both of these resources, I was able to figure out how to successfully get this rig built and on the air. 

One thing that I was afraid of was reading the values of these parts, (well, I REALLY do not do this on a daily basis, so one does tend to forget how to read values)  It was really cool to see that they took the time to put down on paper how to identify EVERY part. They had each part identified right down to numbers, letters, and colors on each individual part and what package they were in. As you can see from the picture below, it made assembling this kit very easy even for a beginner like me.



Rockmite 40 Meter CW Transciever and accessories kit
 (Sold separately)....Altoids box not included 


One thing that was new to me that I had NEVER done before was there was a surface mount ic that had to be soldered to the board. It was a little scary at first because the last thing you want to do is screw it up. By following the instructions and lining up the ic in its correct spot (only took two and a half hours, reading glasses, magnifying glass, a lamp with a bigger magnifying glass, various tools to move it around 1500 times, duct tape, and super glue and only 2700 GD its)  I was able to "tack" one foot of the IC to the board and then finish soldering the rest of the feet to the board using silver solder.



One thing that I found to be very helpful was as I was building the kit, was to separate the parts that I was preparing to install. I correctly verified each part according to the instructions and then taped them to a piece of paper. I also made sure that I wrote down under each part what it was and what the value is. This method is a little time consuming but well worth the effort. I found that by doing this, I did not make one mistake assembling the kit.



My enclosure was an Altoids tin that I have been saving for a couple of years now, just for a project like this. I went ahead and ordered the accessories pack for the kit and it came with all the necessary components to complete the project. I have to say, I was very surprised to see that it took me almost as long to mount the extra components to the Altoids box as it did to build the kit itself!  Here is a great site to learn how to prep your Altoids box by Rod, N0RC. Then of course there was the wonderful task of cramming all this stuff into the enclosure without shorting or breaking anything. THAT alone was a chore. My power source is two six volt batteries hooked together in series, which only cost a couple of bucks at the local Dollar General store. I made my first contact with KR1ST Alex using my Gap Challenger for the antenna.  He only lives about 6 miles from me but man, what a thrill to make a solid contact from something that I built myself. To see pictures of this project in its various stages of assembly, click here




Homebrew End Fed Tuner for 20 and 40 meters



                   
     

This is my end fed half wave coupler .  In the past, whenever I wanted to try to make some contacts with my Rockmite, I was always using my mobile antennas on a tripod.  I tried a couple different vertical mobile antennas with a varied amount of  radials just laid on the ground and had very little if any success. My thoughts were that well, maybe its just because I am running 500 milliwatts on 40 meters, or, maybe it's the sunspots. Turns out that my antenna systems on a tripod just plain out sucked.  It started to become very frustrating not making any contacts. I could hear stations very well, but I did not seem to be getting out very well when I was transmitting.

I realized that my antenna setup was very much compromised and by using it with an already compromised situation where I was running such low power, it would be very difficult to make contacts. I decided to try using an end fed half wave antenna and a homebrew coupler design by AA5TB. When  I originally looked up the schematic, I was not entirely thrilled with the idea.  I figured "Why should I build this when I could just take my MFJ-969 tuner with me and run a random wire with a counterpoise?"... and that is is exactly what I did.

Early this spring, the wife and I decide to take a  weekend camping trip to Givhans Ferry State Park which is about 20 minutes up the road from our home.   I  brought along my Kenwood 430s, the MFJ 969 tuner, a 130 foot dipole, and my 40 meter Rockmite.   I set up my Kenwood and dipole, and had a very successful afternoon making contacts.  Later that evening, when I went back to camp, I set up the Rockmite with the MFJ tuner. My antenna was simple, just a random length piece of wire and a 20 foot counterpoise.  I also had my tripod set up with a Hustler 40 meter mobile antenna and one 20 foot counterpoise for comparison. For some reason, I figured that I would get a better ground if I used a tent stake to secure the counterpoise. This of course, did not work out well. I after doing this, I notice that every time that I touched the tuner, my SWR would rise considerately. I was not really sure why this was happening so I just left it as is and tried sending CQ.  I did manage to make one contact that evening,  but it was very difficult as the band conditions were not best to say the least.

After the camping trip, I come to the realization that it was really a pain to carry the big tuner with me and decided to revisit the end fed half wave coupler
.   Here is the link  to the coupler that I built, and as you can see, it is really a very simple circuit to build for the beginner. This of course, is a prerequisite for any project that I decide to dive into.  I acquired parts to build the coupler, and got to work building this little gem.

 
                          



In my first attempt to build the project, I used a polyvericon capacitor that I had lying around. This capacitor had more than the required picofarads so I figured that it should work just fine. That was not the case unfortunately.  I found that I could not get the coupler to tune correctly even after using a  3.9k resistor as opposed to an antenna as suggested by AA5TBs article "How to make an end fed half wave antenna work" . I wound up tearing apart an old Radio Shack transistor radio so I could steal the capacitor out of it.  This capacitor was 60 pF which is required in the schematic. Once I did that, the coupler worked just fine. I also found that I was able to tune the 17, 20, 30 and 40 meter bands which was really cool.  I did some tests before I put in its enclosure  with the Rockmite. Everything worked fine except for the SWR LED which was a real disappointment. Turns out, the Rockmite does not push enough RF to light up the LED. A slight change was needed to the original circuit which required removing the 10k resistor and installing  an RF stepup transformer. Ater this modification, the  high SWR LED works just fine with 500 mW.  






When I got home that evening, I decided to go ahead and put my tuner in an enclosure, of which I chose a reproduction tin that has been hanging around. After much work, the project was deemed a success until I put it on my MFJ-269 analyzer and found out that I lost 17 and 30 meters. I kinda figured out that it had to be the tin enclosure, as everything worked just fine before I enclosed it. Sure enough, you could see the SWR changing on the analyzer whenever I took loose the lid and moved things around. I thought maybe if I used some electrical tape on the inside of the case it would fix things so I did the whole inside of the tin with tape. Naturally, it did absolutely no good, but on a positive note, I had fun playing with the tape.
 Turns out, the capacitor has to be low for the higher bands and the metal case was acting like a parallel capacitor.  My tape, was doing nothing more than preventing shorts.  What really needs to happen is I need to put it in an plastic enclosure if I want all the extra bands. In the end, since I was able to tune 20 and 40 meters on the QRP CW frequencies, I was happy and decided to leave well enough alone. I have had wonderful results in the field so far using the coupler and a half wave piece of wire with my Rockmite.  At present date, I have had actual QSOs with several QRP stations on 40 meter CW with this setup and am very happy with the end result.  



Son of  Zero Beat and NEQRP project



                                      NESCAF  parted out



One thing that I was disappointed with is the fact that they did not include IC sockets with the kit. You would think seeing that in the instructions it is HIGHLY recommended that you do not solder the IC's for fear of damage, they would include the appropriate sockets in the kit. Thank goodness for the local Radio Shack (You have quesions, we have blank stares) They just happened to have the right sockets on hand which came as a welcome but huge surprise...


This project is actually two kits, Son of Zero Beat by Jackson Harbor Press, and a NESCAF kit from the New England QRP club. These two kits are a little more advanced than what I am used to but somehow,  I managed to cob them together and get them working.  I could not have done this without the help of  Alex KR1ST and Rob KA8JBY who helped me figure out the pinout of the ICs .  The Son Of A Zero Beat kit is a neat little project that helps you "zero beat"  CW station by means of a series of LEDs. For those of you who are not familiar with what zero beating means,  here is a good explanation  by N3E
F Eric.  The NESCAF is a switched capacitive audio filter which comes in really handy when you want to filter out noise or offending adjacent stations.  I have found that this comes in REALLY handy when on the 40 meter QRP frequency and there is another station causing QRM nearby.      



                         Under the hood....

I found that the LEDs were a real pain to put together, but after much trial and tribulation, I managed to cob them together neatly.  I also had some issues mounting the ICs to the board but came up with a clever solution. To see how I resolved these issues, check out the Son of Zero Beat pictures here  I really got confused when it came time to wire up all the jacks, switches, and potentiometers.  I honestly don't think that without Alex KR1STs help, that I would have ever got this thing working. He was kind enough to spend an entire afternoon explaining over and over how to do this. It seemed like the more he explained, the more confused I got because there were so many hookups! He wound up drawing everything out on paper, more or less made me a roadmap of where all the connections were to be made. This was extremely helpful in getting things to work like they should. My enclosure is an old alarm system box that I found at the Habitat for Humanity store, I paid one dollar for it. I took the circuit board out and carefully measured where I wanted to mount my accessories. The LED hole was the hardest to do because it had to be just right. I used a small drill bit, drilled several holes along the outline, popped out the scrap and trimmed it out with a razor knife My hole was not exact which made the LEDs a  loose fit so I used a hot glue gun to fill in the gaps. I also used a black sharpie to give the "illusion" of a gasket.





       Rear view with input and DC power jacks

The two boards are wire together so that you can run each circuit independently or together. They both  will run on either 9 or 12 volts; I have my 9 volt connection tied directly to the 12 volt input jacks so it is really important that I remember to disconnect the battery before I hook it up to a 12 volt power source. The best way to avoid a disaster is to just get a plug and solder the 9 volt battery leads to it for use in the field, this way there is no danger of "forgetting" to unplug the battery.



 Here you can see where I drilled holes to mount the boards and added feet.

                        The Final Product


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