SA2CLC radio stuff

  The time has come to wake up this old gem I've had sitting in the basement for a few years. It's an Oltronix LS107, a Swedish made, regulated power supply with an adjustable 0-500 volts at 200mA, 2 separate 6,3 volt windings, and a 30mA 0-150 volts negative bias supply. This is built up with vacuum tubes (who could have guessed) with 3(!) EL34's, a couple UL84's, UF80's and an 85A2 regulator tube. The circuit is a series-shunt regulated supply, with the EL34's acting as pass elements, while an UF80 shunts the control grid voltage from the EL34's to ground, using feedback from the output to it's control grid, and the 85A2 as reference at it's cathode. Before power up the unit, I begun by opening it, and had a good look at all the components. Nothing looked burnt or discolored. Not even the inside of the cabinet that sit close to the EL34's shows any signs of heat. A good sign. This has probably not been used much.  My initial plan was to replace...

 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...