In my last post, I talked about the changes I’ve made to my 807 prototype jig so that I could investigate the 400v, triode strapped, plate voltage limit. Now I’ve managed to spend some time playing with the high voltage prototype power supply and my newly modified jig. As a result, I’ve learned a surprising amount about the 807 operating as a triode.
Continue readingA comment by “Dave K” a few days ago got me thinking about how I intend to run my 807 power stage and the limitations listed on the data sheet. So it shouldn’t be a shock to anyone that I’ve decided that a little more testing is required. And that required an update of my 807 test jig.
Continue readingI have the initial set of data with the power supply prototype using the Edcor XPWR011 power transformer. It is enlightening and clearly shows which amplifier I need to build next.
Continue readingBe sure to look carefully at the environment where you do your work. Failure to look too closely may result in you sacrificing time and effort to the gremlins in the machine. At least that’s what just happened to me.
Continue readingOne of the risks of becoming too familiar with vacuum tube electronics is that it’s easy to become a little careless when working around high voltages. And because of this learned carelessness, sometimes we don’t take as many precautions as we should. Especially when prototyping.
Continue readingI’ve finished modifications to my test jig to allow the testing of the 6BQ5/EL84. It’s really a shame that so few other 9-pin power pentodes use the 9CV pinout. The 6CW5/EL86 is the only other really common one.
Continue readingSo as I said in my post The Next Amp, I kind of settled on the triode strapped KT88 based on the power supply. Now I’m not so sure.
Continue readingBack in June, in the Competing Priorities post when talking about the 6AS7 SET, I made the following statement:
I also had another idea this morning which may lead to a little more prototyping work to check out a theory I have (another potential delay). But if the experiment turns out well, I may move bias points around a little on the 6AS7.
Well, I spent this morning with some prototype circuits and a stack of tubes investigating the bias points for the 6AS7 SET power stage. And I learned a couple of important lessons.
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