> Geoff/W5OMR wrote: > > > > > Well, I build to match my tubes, not because it is efficient or > > > inexpensive, but because it is esthetic. I am building a linear for the > > > S-Line using a single 4-1000A. Not because its the best way to go, but > > > because I can think of no better tube to have behind a window to look at > > > while sitting in a cold shack.....well, cold before I turned on the Linear. > > > > I dunno... kinda hard to beat a single 304TL > > > > The mail difference being 7.5v @ 21Amp or 5V @ 25Amps? > > > > BTW, anyone have a 5v @ 25amp transformer?
> Jim WB2FCN wrote: > Ah, > That's as follows: > 304TL filament 5 VAC @ 25 amps or 10 VAC @ 12.5 amps > amp factor (avg) 12. freq for max ratings 40 Mhz yeah, those are the two voltages that the 304TL will run... my fumbling fingers meant to say that the "main" difference between the 304TL and the 4-1000 was that the 304TL uses 5v @ 25Amps for filament voltage/current and the 4-1000 uses 7.5v @ 21Amps. For all practical intents and purposes, I suppose I could run a single 450TL in the final, and modulate it with a pair of 450TL's. I have three 450TL's. I just think that behind the glass, a 304TL would look better than a 450TL, because of the (4) 75w plates. What I have in my junk box, is a filament transformer for a single 450TL (7.5v @ 12Amps) and another Sola constant voltage transformer that is rated at 7.5v @ 42 Amps, that would do nicely for the modulators. I'll have to build up a power supply, but I have a plate transformer that will handle the current (220v in - 2000v out, rated at 4.74kVA). And, I have some 872's that will do well for the rectifiers. Also, I have a nice B&W tuning capacitor, with neutralizing capacitors on the back of it, and a B&W HDVL jack-bar, with a 3-turn swinging link and plug-in coils from 80 thru 10m I'd like to use something 'different' for the grid drive, though. Perhaps a pair of 100ohm high-wattage resistors and feed the grid from the center, and apply grid-bias through the center tap of the filament transformer (as well as read cathode/grid current). Or, I could do as John/WA5BXO suggested a while back, and that would be to parallel the three 450TL's, since I do have a single transformer that would handle the filament requirements for all three jugs, and make a "do all" linear amp. The filament choke would be huge (6ga solid copper) OR, I suppose I could wind two filament chokes out of 10ga wire, and put them on either side of the filament transformer, for the total necessary inductance. Thoughts on that? Also, who's got some neat/nifty ideas of broad-band power feeding the final, if I keep it with a single modulated by a pair? This would be, if I went with the link-coupled single-tube final. I plan on using a Viking II as the exciter/VFO. ad-THANKS-vance for any input, from anyone. 73 = Best Regards, -Geoff/W5OMR
