SA2CLC radio stuff

 This is actually the second time I have had this happen. Imagine getting down to shack, to work that ATNO dx, just to find out that your rig does not put out any rf. Last time, it took some investigating to get back on track. I determined that the LPA was not working (low power amplifier). The LPA is used when power setting is below 12W, so it should not be the 100W PA that had failed, because it could not get any power out on the lower settings either. Forum posts advised to look for driver PA mosfets heating, replace driver mosfet etc. I could hear a faint signal in a separate receiver when transmitting so I ordered replacement mosfets, figuring I was going to replace them all. Upon diassembly, I got a bit lazy and just gently wiggled the connectors of the LPA, reinstalled the KPA 100 and tested the transmitter, and lo and behold, it worked. Oxidation or bad contact between the LPA and main board caused this.  My K3, serial 796, does not have gold plated pins on the LPA boa...

 We all have them, projects that for some reason seems to get stuck at some point. I have a few of them (!), and I also have the nasty habit, whilst I'm up at good momentum at an ongoing project, to get sidetracked by something else. I have fixed a few (or perhaps golden screwdriver-ered them) 11m tube radios and cybernet board "export cb's" for a friend of mine. It's fun, good practice and he enjoys using them. However, Jan brought by a beautiful old Tram Titan 2 more than a year ago, for me to fix, and to add channel 24 (in Sweden, channel 24 is the go-to call channel for SSB). Easy enough I thought, a recap and a dds generator to replace a crystal. Turns out, I was in for more. This project became a multi stage rocket, due to the projects needed finishing, so that I could finish this.  First off, the utracer needed to be finished, so that I could test the tubes in the radio, to know if there was any that needed replacing.  My variac needed some work and an outl...

 If you have happened to visit my profile over at Thingiverse, you can see that I havea  few designs concerning radio and related stuff, and of course, I have only published a fraction of what have come out from the printer over the years. I really cannot imagine being without a printer and the possibility to make anything that I need. For intstance, I needed an adapter for a tube socket (German Y8G) to octal. I rummaged through my bins, and found a socket, and also an octal base, from a smashed 6L6. Now, I wanted it som have some stability joining these two, so I designed a piece that mounts to the Y8G socket, and slides into the octal plug. Neat. I use Fusion 360 when designing, and an Creality Ender 3 to print. I added holes that line up with the pins in the octal plug, that way, I can first solder wires to  the socket, guide the wires through the holes, install the socket to the adapter, and then  slide everything into the plug, letting the wire ends protrude thr...

  EM85 under test. A perfect 100% working specimen So, I bought a large amount of tubes from a gentleman, who had been restoring radios for more than 30 years. Many of the boxes was of little interest for me. Tv tubes and pure "bc radio" tubes, but there was a large lot of magic eye tubes, you know, the green glowing things, that was made to aid in tuning in to stations back in the analog VFO era. Function Magic eyes, or indicators, work by directing a stream of electrons onto a phosphorus coated surface.  The phosphor starts to glow green when hit by the electrons, and we can control the way they hit, by inserting a negatively charged element in the way of the electrons or beside the electron stream. By varying the amount of negative voltage, the shape of the beam varies. Different types I mostly had EM84´s, which is a "closing" bar. Used in fm receivers and tape decks among other things. The bar is projected vertical on the side of the tube. I had a few EM80´s and...

 A modern era tube tester? Yes, that´s right. The old radios in my basement was starting to demand a bit more than just swapping tubes. I wanted to be able to measure them. I did not really want an old tube tester, since they are felt overpriced, and building something from a kit or on your own is always rewarding.  A quick google search led me to Ronald Dekker´s excellent Utracer. The Utracer is a computer connected curve tracer, that traces the response of the device under test, on your screen. This gives you possibility to determine plate characteristics on, for example, triode connected pentodes, and there is also a quick test function, to help run through that pile of 6V6´s. uTracer3/uTracer3_pag0.html I ordered his V6 kit, and it came to my doorstep a few months after ordering, due to the fact that he was doing some tests before shipping. Why wait for V6?  Well, since I play with transmitting tubes (807´s, 6146 etc) I wanted a bit higher voltages than his V3 (true a...

2 x 813 grounded grid linear amplifier  This year marks 10 years since I built this amplifier, and it´s been in use on almost all QSO´s I´ve had since then.  When I got into amateur radio back in 2013/2014, I quite soon understood that I needed a vacuum tube amplifier. SB220´s and L4B´s were high on the wanted list, but there wasn´t anything for sale at that moment. I stumbled across a pair of 813´s and sockets, and that´s what set the wheels rolling. I begun by collecting the needed parts. High voltage transformer, variable caps, meters and such, and after that, it´s mostly a job of shaping metal and drilling holes. Most parts collected An aluminum chassis was bent using the sheet metal brake at work. Reinforcement extrusions was bolted to the underside of the chassis where the HV transformer would go. With a finished box a rough layout was determined, and the hole drilling excercise begun. Getting a feel of where to place things Lot of parts to fit. Note that pictured bandsw...