Are there any sensibly priced switching supplies (even surplus) that are small and light, that could power some of the QRO tubes with high current filaments? Would, say, a 5v, 30A switcher which coul
ORIGINAL MESSAGE: REPLY: Surge current would be a problem if the supply is regulated, which most of them are. Just put a suitable resistor in the filament lead with a relay to short it out after a fe
REPLY: What if instead of DC, the square wave (triangle or whatever) from the switchers transformer were used? ORIGINAL MESSAGE: _______________________________________________ Amps mailing list Amps
That's an intriguing question, but I wonder about harmonics of that sharp-ish waveform flying around the RF deck? 73, Jim N7CXI _______________________________________________ Amps mailing list Amps@
Are there any sensibly priced switching supplies (even surplus) that are small and light, that could power some of the QRO tubes with high current filaments? Would, say, a 5v, 30A switcher which cou
My problem with using switching supplies this way is that they are operating in a strong RF field. If the RF causes the switching supply to stop regulating as it should and suddenly increases the out
Why not use a regular filament transformer? Baruch Zilbershatz Nitzanay-Oz 118 Nitzanay -Oz 42836 ISRAEL phone: (+)972-052 8753838 _______________________________________________ Amps mailing list Am
Surplus switchers are available quite reasonably priced versus the much scarcer transformers of the same ratings. Randy AB9GO Why not use a regular filament transformer? Baruch Zilbershatz Nitzanay-O
And the switching supply is regulated and adjustable to provide the desired Voltage at the tube pins. A 50 or 60 Amp supply would be needed for a 30 Amp load, they are cheep as pulls from junked equi
The problem with switchers or using any regulated supply is the cold resistance of the heater/filament is typically 10% of the hot resistance. That issue is automatically handled by the current limit
Agreed! Ever try to hook a headlamp across an Astron power supply? Pretty tough to do.. 73 Jim W7RY _______________________________________________ Amps mailing list Amps@contesting.com http://lists.
Isn't it worst than that for the tubes like the 4CX3000A7 and 3CX3000A7 or the imported GS35B Hence the step start or using a triac to ramp up the voltage. I really like the idea of ramping up the vo
I have a 5A 200A swps for filament, it pull from a TV transmitter ( made in Italy) the ps made in USA.In 1990s, there are some filament swps manufacturers in China. They all promises that if you repl
On tubes, it's even worse, typ 12%. On the few switcher's we experimented with.. all had a built in ramp up feature on start up. IE: with no load on the switcher's output, the output Vdc would ramp
Nope! A linear type. And yes, the power supply was on. It was a 20 or 35 amp supply. 73 Jim W7RY _______________________________________________ Amps mailing list Amps@contesting.com http://lists.con
Even so, the GRC 106 linear amplifier had a linear regulator to feed 2 4CX250, 26 VDC filaments, in parallel with no problems. There are types of linear regulators that don't latch up at start condit
But the 4CX250s have low powered, oxide coated cathodes. The larger tubes are 225 watts for oxide coated cathodes (YC156) and nearly 400 watts for the 4CX3000A7. Some in the 3000 to 5000 watt range r
a directly heated [thoriated tungsten] GG triode. However, ur scheme would work with directly heated tetrodes.... like a 4CX-5000. Jim VE7RF _______________________________________________ Amps maili
Jim, please bring me up to speed on why the switcher will not work with a directly heated tube. I am not challenging the information; just asking for enlightenment! 73, Gerald K5GW In a message dated
I think making the switcher "ramp up" is pretty easy as most of them already ramp up their voltage at start up by varying the pwm duty cycle. I've done quite a bit of experimentation on this for a s