Hi, I am planning to build a PA for 20 meters and I saw interesting designs using power MOSFETs. One of the difficult points in such designs is input matching due to the high gate capacitance of the
Hi, I am taking apart an old HV power supply made in the late '40s, probably in Germany. From its size, the power transformer should be rated for approximately 1 KW. It has an HV secondary winding 80
You mean something like this? See schematic attached 73 de Angel Vilaseca HB9SLV _______________________________________________ Amps mailing list Amps@contesting.com http://lists.contesting.com/mail
Hi Barry, Tnx for your answer. I'm positive. I disconnected the cap from the xformer and measured it. It is a hefty thing, measures about 3x4x1 inches. No polarity. Most probably an oil-filled paper
Dear Bill, Tnx for your answer. So let's try to guess what happens if I remove the capacitor... There is no parallel resonant circuit any more, so the power line "sees" a much lower impedance, so the
Hello Ian, What is a power factor correction? What is its purpose? While looking for info about constant-voltage transformers I found a thread on this same mailing list dated May 2003. It said that c
How about using a 15 V Zener instead of a hot-carrier diode? I think that the gate of the HV MOSFET should be grounded for AC. So in the end we have what the name of the thread says: A grounded-gate
Hi snip snip What could a wrong resonant condition be? Resonance frequency can be -much too low (what happens then?) -a bit too low just as you just wrote, -slightly too high, which is what we want i
Hi, I just read in a book dated a few years ago about an interesting device, but could not find it in my parts catalogs. I wonder if someone has tried it. It is an optically-controlled triac, called
Hi, I am building a 2500 V power supply for a one-KW transmitter. It will use 2 4CX20Bs. I have two oil-filled capacitors: 2.5 KV 40 uF and a 4 KV 25 uF. I feel quite uncomfortable using the 40 uF 2.
I am not sure about this. 4CX250Bs should be quite indifferent to HV hum, if screen voltage is well regulated, so I would rather concentrate on the latter. What do you think? I will do that, right no
First of all I would like to thank the group for the many answers I got to my question about lowest possible capacitance in a HV PS. Now this is what I call valuable advice. Thank you all for your he
Hi, I am building a kilowatt shortwave amp. I need a switch to short-circuit a variable part of the coil in the output pi-network to tune into every amateur band. Unfortunately, heavy-duty, ceramic w
Hi How do you do this? Switching several Kilovolts must surely be done with an expensive vacuum relay? You certainly cannot switch the HV transformer primary on and off every time you cycle between x
How could such an amp be converted for shortwave use? Can it be assumed that a broadband 4:1 transformer (ferrite toroid core) at the output is all what it takes to get it running on the shortwave ba
I made a search with Google and I found the Amplifier research Model 200L mentioned in a text about an experimental plasma generator. Could you please make some info available? I am currently buildin
Hi, I am currently building my first HF amp using a couple of 4cx 250b. I have found in the literature that the plate choke is quite a critical component and I found a few kinds of plate chokes desig
I am building a 3.5 to 30 MHz amp and I have been following this interesting thread. I have a question about the *other* choke in the output circuit, that is the one that is wired between the antenna
Hello Richard Thanks for your answer. I do not have a professional background in electronics so from time to time I need to ask some questions that will probably seem quite basic to many of this list
Maybe you could stack 3 T-400A-2 cores Angel HB9SLV _______________________________________________ Amps mailing list Amps@contesting.com http://lists.contesting.com/mailman/listinfo/amps