Home |
Search |
Today's Posts |
|
#1
|
|||
|
|||
Modulation Inductor?
Tony,
I did exactly what you are describing. I used a solid state audio amp, and drove a tube type audio output transformer backwards to step up the impedance from 8 ohms to several thousand ohms. I used a 4 uf oil capacitor to couple that across a HV choke that carried the RF final amp plate current. For a choke I used a 125 watt Stancor poly-pedance modulation transformer where I used as much winding on the primary as available. It worked very well. It might be easier to consider cathode modulation, and in this case the transformer turns ratio will be much less, and the HV problem will also be less. Maybe a 110/220 vac to 12vac 5 amp filament transformer will work out here. This is just a guess, but it might work. Cathode modulation is a combination of plate and grid 1 modulation, so the % eff is somewhere between 66% (plate) down to 33% (grid) , and might end up at about 50%. Consider the 220 vct winding where the grid return goes to the CT, and the cathode goes to the top of the 220 v winding, and the bottom of the winding goes to ground. Your turns ratio need may vary, but the concept proposed is workable. Jim WD5JKO "Tony Angerame" wrote in message ... I've acquired a high power 50 watts plus tube type hifi output transformer. I'd like to try modulating a pair of 6146's with a hifi amp. The circuits I see use a modulating inductor in series with the B+ to the final to keep single ended dc off the transformer secondary. Here's the rub. Where do you find a 30-50 henry inductor for 800+ volts? I was thinking of checking out the secondary of a tv transformer? (Not many left used to be common whatever happened to those tv's). Anyone have any ideas on winding one? Seems to me taking an old transformer apart and scramble winding as much wire as one can afford might do the trick? Ideas? Thanks, Tony, WA6LZH |
Reply |
Thread Tools | Search this Thread |
Display Modes | |
|
|
Similar Threads | ||||
Thread | Forum | |||
Info needed on "Taylor Modulation" from the 50's. | Boatanchors | |||
Power Inductor Optimization... | Homebrew | |||
Power Inductor Optimization... | Homebrew | |||
Current in antenna loading coils controversy - new measurement | Antenna | |||
NCI Position for Rulemaking | Policy |