A secondary issue on the filament transformer grounding/ungrounding: When the transformer secondary is floating, it then becomes important that the transformer primary to secondary breakdown voltage
Hi Will, I am interested in info on the gas discharge devices. Seems these might be more precisely set than a gap device what with air/altitude effects. 73/k5gw ______________________________________
I found out the hard way that 1A and 3A protection diodes can't handle a 3000vdc plate to ground arc. A good sized hv filter C, say 50uF, stores enough energy to destroy them, even with a series 50 o
I also agree with the not grounding of the filament. It has been my experience though, that 1N5408 diodes can be destroyed by a 3500vdc discharge through a 25 ohm glitch resistor. Perhaps the dischar
This WinLink issue went right by me. WTF is this all about? What does it have to do with our FCC license? Please enlighten us (me). 73, Gerald K5GW _______________________________________________ Amp
Hi Dick, I guess we all have our pet designs and as usual, there is more than one answer. I have seen enough KAPOWS! over the years that I tend to design towards minimizing them. If the cathode is co
Hi Bill, if by "floating the screens" you mean no voltage applied and no path to the cathode, then this is not a good thing! The screen voltage will very quickly rise to the plate potential and with
I lost track of who said what/when; In a sine wave the average voltage is zero therefore average power is zero.In an ac circuit with sine wave voltage, average current is also zero. One could be led
I power is No fault found with why average is not zero. This is the part I was responding to: I guess you meant instantaneous VOLTAGE rather than power? Otherwise you would be finding the RMS value o
And, along a similar vein: If a string of 50% duty cycle dots at say 50 words per minute are transmitted, what should the Bird meter show for power output compared to full carrier? 73, Gerald K5GW In
And, along a similar vein: If a string of 50% duty cycle dots at say 50 words per minute are transmitted, what should the Bird meter show for power output compared to full carrier? What are the rise
Someone asked me recently if the tubes in their Alpha 78 might be going soft (they were measuring poor efficiency on 10 meters). My response was to inquire about their measurement technique in order
Good point, Gerald. A more likely explanation for the low efficiency on 10 meters might be a combination of higher tank circuit losses and wattmeter calibration error. Still, I hear people talking ab
Unfortunately my Bird 43 has no peak reading option. It did have the option once upon a time but I got tired of it eating 9v batteries and removed it. I have also "discovered" that the screen voltage
Much more can be said about the voltage rating of these power resistors. The failure mode resulting from over voltage operation is an open turn (and there are a bunch of turns, increasing the probabi
There was one more "gotcha!" failure mode that comes back to mind: My 2m 8877 PA hv power suplly uses two 100uf 3000v oil filled caps in series. The big power bleeder resistor had gone open as mentio
Hi Guys: Appreciate your generous help on my previous matters. Permit me kindly to ask for help on this one. I have a 1948 homebrew using 2 each 1625's in RF deck. Its modulated by 2 each 807's. It w
Dick, I'm not saying it's a bad tube, and dont want none to think that. I just dont want anyone to undercool the tube so it will last. Who knows, the 4CX1500 may have an over-sized radiator too! Abou
Or, one can tape a big plastic garbage bag to the top of the amplifier and time how long it takes to fill the bag with air. If a 20 cubic foot bag fills in 20 seconds then you have a flow of 60 cubic
I have been experimenting with some NTC thermistors to use in a filament transformer 120vac primary to limit the secondary (tube filament) current flow. The unit showing the most promise, model CL90,