The control board

This is the first board you tackle with the Elecraft K2 build project. Before I go on about the control board one very important step needs to be taken by EVERY Elecraft builder. If you are not already a member of the Elecraft reflector it is NOW time to do so!! This is a fantastic resource for information, trouble shooting and question asking. Make sure you register with the reflector so you are able to ask questions. How does one registrar you's easy....go to the Elecraft site .   At the top of this page there are links one is called email list It is here you will find how to register and get in on the action. As you progress in your build  you can be a help to others who are progressing in their build.
 In this page I will be posting pictures of the control board build. I find that sometimes that not always do the printed instructions answer all questions. ...sometimes a picture is worth a thousand words. Also I will be adding tips and tricks as we go along in the assembly of the control board. 
The control board is great spring board into the radio build. You have the chance to build your confidence with parts placement and soldering. With the control board parts are spaced comfortably for soldering, there as of yet are no dreaded toroid to wind and solder in place and most components are large and easily soldered. There are some nice challenges also, some crystals have to be carefully soldered in place and the "can" has to be grounded with a spare component lead.

Some things to remember during the control board build
  1. Before soldering components double check to make sure you have the right component and that it's in the right spot. This sounds like it can add some extra takes more time to troubleshoot a misplaced part, remove the part and not damage it and double checking will result in a lower frustration level.
  2. Have faith in Elecraft and follow the instructions. Their step by step component placement has been well thought out. Read each step carefully as sometimes you are asked to trim and not trim leads, to solder something only for very short intervals and so on. 
    Always store in anti static bags
  3. The manual has "check out" sections were you will be doing resistance and voltage checks. Do these and don't skip them, if you have some odd results email Elecraft and the Elecraft reflector. You WILL be very surprised how fast help arrives in your in box of your email. 
  4. If  you start to feel tired, getting frustrated easily or missing key points in the manual that pertains to the step of the build your involved's time to take a break or call it a night.  Always remember this is to be a pleasurable experience. It just may had been one of those days at work and surfing the net, reading a book or vegging at the TV may be what you need. 
Some tips and tricks 
  1. As your control board build progress's the components will start to pileup and you will see less and less spare room on the control board. For this reason where possible I try to keep in mind the ability to read components part numbers and or values. In the future if trouble shooting is needed the ability to read values or part numbers can simplify things.
  2. Those three legged transistors in the past gave me trouble as I tried to bend the fragile legs into a
    tripod configuration  to fit the board. This link shows an easy way I found to get it right the first time without any over bending of the transistors legs and possibly snapping them off. 
  3.  The accessory connectors are a combination of gold contacts that are encased in a plastic housing. One has to be very careful when soldering these as the plastic can very easily melt. Once I have the connector tacked in place  I solder the connector in place by alternately soldering from one far outside edge and back to the other outside edge. I avoid soldering one after the other as the heat can transfer and you may find yourself melting the plastic casing. 
  4. The grounding of the crystals or "cans" as they are commonly called can get frustrating. Here is what I do.....after the crystals have been soldered in place. I take my time in forming the grounding lead and make sure it fits nice and neat. I make the lead long enough so it can be folded over on the opposite side of the board. This helps hold the lead in place while soldering it to the crystal and I also add a 90 degree bend to the top part of the ground lead so it can sit on top of the crystal. Once the lead is made up it is placed off to the side. I then add some solder to the top of the crystal. I found this helps greatly to speed up the time it takes to solder the ground lead to the crystal. As a side note I have seen some builders solder the ground lead to the side of the crystal. There is nothing at all wrong with this but I avoid it because if you have a row of crystals I would find it difficult to solder on the side. Also adding my pre-solder before attaching the ground lead would also be more difficult on the side of the crystal for me. Once the top of the
    Getting it to fit just right
    crystal has had a small amount of soldered added or tinned as it's called. I then fit the ground lead through the PC board hole placing the 90 degree bend on the top of the crystal. At this point the lead on the opposite side of the PC board is not bent. I hold this end with a small pair of needle noise pliers and pull very gently down as I touch the top of the crystal with the soldering iron tacking the ground lead in place. I then bend the lead on the bottom of the PC board and solder that lead. Then it's time to go to the top of the crystal and add a little more solder to firmly attach the ground lead to the crystal. I then trim the lead on the bottom of the board. 
  5. Soon the time will come to bend some leads on another type of transistor, these have three legs as well. On these ones Elecraft wants you to bend all three legs 90 degrees. These power transistors have to go onto the PC board and match a printed layout on the board. Here are some pictures of how I bend these leads so when the transistor is placed on the board it matches the layout on the PC board. The trick to bending the leads of a power transistor is to place the screwdriver on the bottom side of all three leads. Then move it so the outside edge of the screwdriver is in the middle of the large section of the transistor legs. Once there bend the legs of the power transistor and in most if not all cases I find this works fine. The screwdriver gives a nice roll to the bends as opposed to a sharp 90 degree bend.

No comments:

Post a Comment