A couple of points here. 1) You can apply HV any time you want. Just don't draw any cathode current during the six minute warmup. In other words, keep the cathode biased negative with respect to the
Yes, well, as George Daughters pointed out, please do reverse the polarity I indicated for the cathode voltage relative to grid. As anybody who's done grounded grid amps would have surmised, it is PO
WSPs aren't that bad. We've done a few solder-bumped WSPs, with 20mil (0.5mm) center-to-center spacing on the pads. There are rumours that industry is going to head towards 0.4mm and even 0.35mm, but
Ed, The difference between the '1200 and '1500 in feedback capacitance is only 2:1, and both are very small, indeed. While there are the occasional reports of oscillations with the '1200, it is more
In the early broadcast days, when broadcast power could only be achieved by running many tubes in parallel, it was common to have "reasonably" separated feed systems for the tubes. The power supply h
I do not think that is correct. My SB-220 does not use the neutral. It uses hot-ground-hot in the power cord. The "third" wire is connected to the chassis, and goes to the AC line's ground, not the n
Since neutral is normally used to conduct return current, when used as neutral, there is guaranteed to be a difference of voltage between neutral and ground, in the shack. That's the rub, when you do
(snip The function needed by the SB-220 is ground only, it does not need neutral, as causes no currents to flow in that wire under normal operating conditions. No, there won't. The center tap of the
In the late 1980s, one of the engineers I worked with had recently come from Continental Electronics of Dallas, TX. The most recent transmitter design on which he had worked at Continental was a mult
The documentation part is done. Check out the textbooks and articles written over the years by W1FR, Fritz (aka Frederick) Raab. He has built and documented an envelope removal and restoration high e
I have a project going on and need a couple of variable caps. These once were standard Johson parts, and I can buy them new from Cardwell, but the prices are... well... I like my wife too much. Would
I moderate a couple of jazz email lists that use the same Mailman software as AMPS. Mailman can be set to accept or reject postings based on various criteria. Moderators who care about spam and virii
I'm in the final stages of building a small hipot tester. The last item I need is high voltage rectifier diodes. My diode stacks need to withstand 20kV. I know I can series lots of diodes, but this b
I first used Heyboer transformers when I needed custom transformers for commercial product in 1982. Quantities purchased were in the 10,000 to 50,000 per year range. Very nice prices, never a problem
Design your screen supply based on average current. You should have a screen bypass capacitor which supplies the peak current that you are calculating of 100mA. If the screen supply stays in regulati
Routine maintenance manuals for industrial equipment suggest that oilite bearings (oil-impregnated porous bronze) lose the lubricating qualities primarily because the oil wicks onto the motor shaft,
I've been watching the resistors and diodes thread with some interest. I see one point of misunderstanding, and that is about reverse leakage current. The more accurate term is the reverse saturation
When I was but a wee 14 year old, I toured WKZO radio, 590kHz, in Kalamazoo, Michigan. The Chief engineer was Maury W8EMD who became one of my elmers. The transmitter was a 5kW RCA Ampliphase system,
I've been musing for many years about what keeps a manufacturer making tube type amps...the commonly-heard phrase is that "any amplifier manufacturer is in competition with estate sales". Well, it se
Years ago I was faced with an existing design that loved to weld relay contacts closed. The open circuit voltage, and the closed circuit current, both fit within the relays specifications. There was