Posts Tagged ‘Projects’

Time to make a choke balun


In your ham radio adventures, you may have heard the words..choke balun, feedline isolation, common mode choke or a 1:1 balun. In my humble opinion different names for the same device. These devices for the most part are present in a system to control common mode currents. I am not an engineer just a simple ham guy trying to sometimes understand some very complicated and technical explanations. 

I hope to keep the next bunch of lines understandable. Here we go...what are common mode currents! Most ham use some form of 52 ohm coax as it's very easy to route, secure and can within reason be placed anywhere. Ideally, RF will flow out on the OUTER SURFACE of the coax INNER CONDUCTOR and flow back on the INSIDE SURFACE of the coax shield. This is what happens in a perfect world but if a system is unbalanced RF current will return on the OUTSIDE of the outer coax braid. It does not return but it radiates.

This is when we hams can experience RFI issues and these issues vary with the amount of common mode currents flowing on the outside of the shield of the coax. How does one control this common mode current? One very effective way is to introduce a common mode choke, 1:1 balun, choke, feed line isolation or whatever else it could be called.

In a previous post, I did go over how I installed a 1:1 balun at the antenna feed point of my Hustler 4BTV and that seemed to satisfy my RFI issues but further reading informed me that a choke balun at the radio feed point would be very advantageous. I ordered 2 FT240-31 mix toroids as I decided to make a choke balun instead of buying one. The two common mixes for HF toroids are 31 and 43. The difference being the 31 mix is effective from 1-300 Mhz and 43 is effective from 25-300 Mhz. I chose to go with the 31 mix and purchased 2 from a reputable dealer as not all toroids are created equal. I would be very wary if you find toroids at a very low price....just remember you get what you pay for. I ordered mine from Mouser Electronics Canada, part number 623-2631803802 made by Fair-Rite for 13.00 each.

I used RG8X coax to wind around the toroid but the issue with using a ring toroid compared to a split bead is I had to remove the PL-259 to wind the coax around the toroid and then solder the PL-259 back on. I intended to make 10 loops and for some reason, I ended up with 11 turns through the toroid. I then soldered the PL-259 connector back on but not before placing the barrel and coax spacer many of us have soldered a PL-259 on and then realized we forgot the spacer and barrel!
Another advantage to having a choke balun at each end of the coax is that it helps remove some RF noise that is picked up on the shield of the coax.

Dont forget these BEFORE soldering the PL-259

FA- VA4 antenna analyzer kit.

The condo kit corner.
About a month ago my FA-VA4 vector antenna analyzer kit came in and it has sat idle until Friday. I had the day off and with everything done that needed to be done, I say "everything that needed to be done" because there is always something to get done! I decided it was time to put the kit together. This really is the first kit I have attempted to assemble since moving into our small condo in Toronto. I no longer have the huge desk, nice lighting and the room to place all my equipment around me. Now it's a roll top desk with 2 slide out shelves, that is my only choice for kit work now. Trying to get the exhaust fan, soldering station and other small miscellaneous items in place is a real challenge. What was also a challenge was remembering where the heck I placed things in the dam condo! I have a nice Panavise setup for holding my boards in place while soldering. I could find the arms but I was not able to locate the base. I looked everywhere but had no luck and nothing bothers me more than knowing it's somewhere but just not able to find that "somewhere". I had to settle for placing just the Panavise arms on the slide out and do my best. I found very quickly that working in a tight space one has to be very aware of cords and tools, a few times moving the soldering iron in place almost had the soldering iron cord take the make shift Panavise (holding the circuit board) onto the floor. The kit from Box73 comes from Germany, the shipping time was fantastic as well as packaging. There is no SMD work to be done that was done and I only had to mount some connectors, power on switch, pushbuttons and the LCD display. After being away from kit building for a very long time this was a nice way to jump back into things. I first took an inventory of the parts and this is something I always do. I hate getting to the point when a part can't be found and your not sure if it was not shipped or misplaced by me? Doing the inventory allows me to contact the vendor and in the case of large projects the part arrives in time for that point in the assembly. Everything was there and it was now time for the next important over ALL the assembly instructions. In my case I go the extra step and check out YouTube videos and the internet to see if there are any pointers that others have come across to make things easier or things to avoid.  One of the builder beware tips I read was from John AE5X blog to not use lithium batteries as the voltage is to high and the FA-VA4 will repeatedly reboot. This type of information is invaluable when kit building. It saves trouble shooting time and going down possibly a long road of parts testing.
This kit does have SMD parts that I said are factory installed BUT some of the items that the builder needs to install are very close to some SMD parts. This brings me to another important part of kit building....spend the money to get the right tools for the job. In this case my Weller WES51 has a large variety of soldering tips. I find the fine chisel tip (Weller ETM) worked great for soldering the LCD terminals, the larger tip for the BNC connector (Weller ETD) and finally the intermediate tip for the components beside SMD parts( Weller ETB).
The instructions had me installing the ON/OFF slider switch first and this was a great start for this old rusty kit builder.  I then moved onto the 3 rails in which the LCD would eventually plug into. You will notice from the picture these are raised up on the board. Each pin has a "collar" so the rail will be at the proper hight but the builder has to be cautious and make sure the rail is firmly seated and upright and straight. One rail is 20 pins and once it's's in! In the past I have had to remove these types of components due to my own lack of attention. IT IS NOT FUN and I have a Hakko desoldering tool  which make desoldering a pleasure but even with that tool removing a 20 pin rail is not fun at all. Take the time to set these parts up for first time correct soldering. My method was taping the rail in place, solder the 2 opposite end pins, check for upright correctness and firm seating on the board. If all is good solder the remaining pins. The other components were easy to solder in place when using the proper tips. I have a magnifier head set  and use it to make sure all connections are soldered properly and that all were done. You would be surprised how many times when multiple pins are involved how easy it is to miss a pin.  The LCD needed to be soldered to the backlight, it involved a 20 pin connection on one side. The instructions said I only "had" to solder the 2 outside pins. I chose to solder all 20 and then on the opposite side of the LCD there were 2 sets of 3 pin connections that need all pins soldered. To make sure the LCD was firmly against the backlight I used some tape. Once the LCD was ready to go again I took time to inspect the pins that were going to plug into the 20 pin and two 3 pin rails. I did find one of the 3 pin setups ups on the LCD was bent! I corrected this but if I failed to see this could had resulted in broken or bent pins.
There is two AA battery holders that need to be soldered in and all I can say is check and double check this. Mixing this up polarity can bring smoke to the smoke test. Believe me it can happen. One of the Elecraft K2 kits I put together almost ended in disaster when I was not paying attention and soldered up a power cable with Anderson pole connectors. I soldered red wire to Anderson black connector and black wire to Anderson red connector. It gets better.....I then plunged it into the K2 and powered the K2 on!! The Astron power supply made a noise and both the inline fuses on the main Astron power supply blew. I was very luck and now double check everything.
It was now time for the "smoke test" and I was so proud of my first kit in over 4 years I had my dear wife Julie come over for the ceremony.......I flipped the switch and........yup you guessed it...NOTHING!!!!! Yup nothing.....but no smoke and that is a good sign. Julie giggled and moved on to other tasks. I made a mental note to always solo a smoke test and avoid the embarrassment. The problem was one of the AA batteries was not firmly in place. Once looked after the power on test was a success. I called Julie over for her to check out the kit but it just did not have the same excitement. That was it for the kit building for the day I still have to preform the calibration. Over all the kit was a  joy to put together and by way of some side notes. The case is a brushed aluminum with attention to detail such as counter sunk screws for securing case, the LCD and buttons lined up perfectly and a nice touch was not having stick on rubber feet (that always over time seem to come off and get lost) This kit came with pull through rubber feet. I still have to calibrate the unit and actually use it but that will be another day.
Completed kit
Smoke test 
Bent LCD pins 
Supporting the 20 pin connector.
Completed LCD pins 

Project collaboration

During my working life I collaborate with a large groups on multiple sites and we do stuff together. When I am attempting a radio projects I take on a different tack. I attempt to be either an expert in many things or I follow sets of instructions slavishly. Most of the time it takes a long time and there are numerous failures or dead ends along the way. I’m not sure why I do this.

There are many websites that will offer support to the frustrated builder or keen expert. But few that offer hobby collaboration (or at least I haven’t looked too hard but a quick trawl didn’t really yield much). I wonder why that is? A probably misquoted quote goes along the lines of ‘Travel alone, travel fast. Travel together, travel further’. You could argue that sites such as forums offer support and collaboration by using a project management analogy, I can not agree with that. Tasks are not identified, resources are not defined and task durations are not agreed. Expertise is sought, sometimes this results in no responses.

A local ham was at the centre of a project that has now become a major SDR rig. He worked from home, in the evenings with a group spread around the world. They have developed a really astounding product that is now sold as part of the Apache Labs brand. Why is this approach not prevalent?

I’m not offering a solution, just a question. Does a place exist or am I right in assuming that there are some international superstars that produce lots of ‘things’ from 3D designs through to circuit boards and kits that hobbyists use? I think there ought to be a place where we can go to collaborate. I just don’t know where it is or how to engage with it….yet.

PART2: Mod for Signalink USB so it can be used with 2 radios

The finished product
Below are some of the options I came up with to see if I could get my Signalink USB to work with two different radios……
  1. Rewire the internals of the unit each time I switch radios, this was just not an option as it is time consuming and the unit I believe over time would not stand up to these continual wiring change outs.
  2. To purchase Signalinks plug and play boards, you simply plug in the board for the K3 or the KX3. This is for sure an option but again I was wanting to not take the Signalink apart each time I wanted to change out the radios.
  3. There is also the option of purchasing a second Singalink USB unit but this is very pricey for what I wanted to do.
  4. Try to figure out if it is possible to set up the internals so with the simple flip of a switch mounted on the outside of the unit I could change the internal wiring to make either the K3 or KX3 work. This was the option I decided to work on.
    internal mod wiring
So settling on option 4 as my choice I set you to see if and how it could be done. I did an internet search because the way I look at it is why try to reinvent the wheel if someone else already has! My results turned up only 2 that I could find were the unit was being used for 2 radios. Both did not seem to suit my need. The first seemed the operator configured a device that allowed the use of two of the same radiosbut at different locations. Each radio could be controlled by the same Singnalink unit. The other site I found this op used 3 RJ45jacks in a separate box to do just what I wanted to do…BUT…..I was looking to not have yet another “box” I was ultimately looking for an “all in one” solution. I ended up drawing out many possible circuit diagrams and at one point almost finished wiring what I thought was the "solution". I then realized it just was not
One final check before assembly
going to work and had to hit the drawing board again.  I finally came up with a workable plan that involved drilling only two holes in the back panel of the Signalink. I had to install a ON-NONE-ON mini switch and a hole for an RJ45 pigtail to be placed. Some of the things I ended up learning as I went along were: 
1. A long pigtail had to be made on the connections between new rear panel switch and the 8 pin DIN wiring. This allow the removal (if needed) of the circuit board.
2. I had to solder the wires into the 8 pin DIN they just did not stay in place and with the extended pigtail there was lots of movement in the wires as the covers were put in place, I didn't want any wires coming loose once assembled.
3. I ended up removing the pigtail and adding a rubber grommet as the plastic housing seem to have a sharp edge to it.
 Below is my diagram for the mod, the "K3 Signalink RJ45" is the internal jack on the unit. The wiring shown in my diagram for this RJ45 is the wiring that is on the circuit board and does not need to be added. Also on the 8 pin DIN there are jumpers between Spk-1, GND-5 and GND-6.  I have tried the unit both with my K3 and KX3 and it works great. The final thing I have to do is just label the rear switch.

PART1: Mod for Signalink USB so it can be used with 2 radios

Rear view before the mod's
Soldered jumpers
In an order to simplify my digi setup with the Elecraft KX3 I wanted to take advantage of my Singnalink USB unit. I currently use it along side of my Elecraft k3 for digi mode operations and I have thus become accustom to how it works. So it only made sense to also use it with the KX3 setup. One major issue I had to see if I could overcome was modifying the Singalink USB device to work with 2 radios? The issue was that the Signalink USB has to be internally wired (by the user)to work with a specific rig and I wanted it to work with 2 rigs! Before even going forward with this adventure I had to open up the Signalink unit and do some long overdue maintenance. The Signalink was purchased used and for some reason the previous owner soldered the jumper wires that configure the unit to work with a specific rig. These jumpers are designed to be plug and play, this way you can reconfigure the unit to other radios if you change your rig over time. The 16 pin IC DIP socket was melted and of no use for what I had planned for it. I set the socket up for my Elecraft k3 and these wires I had to solder in as the socket would not allow the “plug and play” feature due to the previous owner. These wires had to be cut out and then the fun job of removing the 16 pin socket! I have built many kits in the past including 2 Elecraft k2’s. As all kit builders can attest to no matter how careful you are mistakes happen. When the mistake happens of soldering a part in the wrong place……the removal of said part can either go well or very bad! I have had it go both ways and as a kit builder one investment that has saved me many a time is the Hakko 808 de-soldering pump. I used it to remove this 16 pin socket and when finished it looked like nothing had ever been installed on the board. I have tried spring loaded de-soldering pumps and the solder wicks but the Hakko solder pump make all jobs painless. Now with the new 16 pin socket soldered in it’s time to look into making the Signalink work with 2 radio…………coming up in my next post “ how I made this happen and it’s working very well”
After the Hakko 808 is done

Elecraft surgery part 3 of 3

Back to life again
It's time to solder in the new P30 and P35 headers into the K3 then put the rig together hold my breath and plug it in! Now that the old headers are out and the solder pads are cleaned off I now want to fit each header into it's spot and see how they fit. Then I will solder them in and it's very important these headers sit flat on the board. Here is the process I use to solder the headers in, I first only solder the 2 outer most pins. This allows me to reheat the pads if the header is not flat on the board if you solder 4 or more pads at once it's very hard to reheat them if you have to reposition the header. Once I am happy the header is sitting properly on the board I then solder the rest of the pins to the board. I
Soldering end pins 
don't solder them one after the other but instead I solder every other pin and then go back and solder the other pins. I do this because the plastic that supports the pins do get hot. I found if you solder one pin after the next the plastic supports have melted on me. Once the top side has been soldered I then turn the board over and solder the bottom solder pads in the same manner. Now that the pins are in I take a break and then come back and take a very close look at the pins. I am looking for proper soldering job,

Imports of checking both sides of board
also there has been no flow of solder from one pad to the next. Finally that I did solder all the pins, I have had this happen in the past were I have missed a pin. This is why I take the break as I have found if I don't I end up seeing what I want and I miss the unsoldered pin because I want to get to the rig put back together and try it. Satisfied with the solder job its time to clean the solder pads and I use a tooth flossing brush with 99% alcohol. This cleans off any residue and the alcohol evaporates. With the new headers installed it's time to put the rig back together and do the smoke test. At this point it's very important to take your time as you put the rig back together. There is the excitement in getting the rig back together and see how it work! This is the time you forget parts, not tighten parts, rush and misalign parts. Great care has to be taken when mating up the new headers. I had all go together well and as you can see from the picture at the top of the post the smoke test went well.
Flossing tool used to clean board
New header lines up with front board. 

Part 2 of the K3 surgery.

It's time for the surgery
Beware of other components 
It was time to heat up the soldering iron, hold my breath and begin the surgery! First off you have to get to the P30 and P35 headers. Taking the radio apart is a very important step that close attention is required. Don't take short cuts, for example screws that are removed put them somewhere safe. When handling the rig use an anti static mat and wrist band. Finally when handling covers and boards be aware of fragile components, the last thing you want to do is damage components. Once the rig is apart I identify the components to be changed and made sure they really were P30 and P35. I then look at the parts Elecraft sent to me, last thing you want to do attempt to install an incorrect components. I now looked at the PC board and become familiar other components, wires or anything that I could damage when soldering. I have found in the past when concentrating on a very small section of a PC board you could at the same time place your very hot soldering iron close to sensitive comports and your not even be aware you are doing it. With my project today I had to move a wire that was close to P35 and I have to be aware of 2 components that
Front control head removed
Fume trap and soldering iron ready
are close to the pins on header P30. The first step is to cut the header pins right  the 90 degree bend and I am left with pins protruding from the board. With this completed I am left with pieces of pin sticking though the board that have to be removed. It's now time to setup my soldering station, fume extractor and solder feed station. What I do is hold the pin with my needle noise pliers and heat the solder pad and at the same time pull the pin out of the board. All but two pins came out which considering how many pins had to come out I was pleased with the results. I am left with solder pads to clean out (both top and bottom of board) and work on getting the 2 stuck pins out. The best tool to clean the solder pads is my Hakko 808 desoldering tool, it does a clean and fast job! With all the pads clean it's time to deal with the 2 remaining pins. I decided to trim the pins down close to the board and use the Hakko 808 to suck the pin out once it melted the solder. It worked great and I am now ready to install the new headers.
Trimming the header pins
The two stubborn pins
After using Hakko 808
Old out and new ready
The installation of the two headers is going to be part 3 of the post I have added some extra pic's or the removal of  P30 and P35

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