I'd expect that our cost is a lot higher.
After the run is done, we count the parts on each reel, with our new x-ray machine, and then put the partial reel back in stock.
-- John Larkin Highland Technology, Inc picosecond timing precision measurement jlarkin att highlandtechnology dott com http://www.highlandtechnology.com
e about 2500 of them, in storage. I need to build some clean 90-100VDC powe r supplies for old battery powered tube portable radios.
I was thinking of a little above 2MHz, to eliminate any birdies. As long as it is above the highest frequency on the AM band, plus the IF, it wouldn't cause any problems. I could use a pair of the transformers with primaries in parallel, and all secondaries in series. Add that to the Plus terminal o f the battery, if I need a few more volts. These batteries have been obsole te for decades, and there are several less than optimal 'battery packs' tha t show up for sale. The worst uses ten, 9Volt batteries in series. They are so cheaply designed that they don't even bother with battery clips. They c ut one in half, for each end of the stack. D cells in series power the fila ments.
When used on AC, it uses a current regulating ballast to power the series s tring of filaments. The plate and filament voltage are critical on the LO t ube. That tube has been out of production for about 20 years. These radios original used Octal based tubes, but switched to miniatures early in the pr oduct life.
A decent replacement for these batteries can cost $100. You have to manufac ture a case and the four pin connector. Unlike most HV battery packs, it ha s four pins, exposing the 90VDC output. I bought some decent looking sheets of 3mm Phenolic sheets. I plan on adding a small push button switch in the center of the connector to turn on the HV after the radio is plugged in.
The cases will likely be made from .250" Lauan plywood. I have about a doze n 4' by 8' sheets I picked up from a body shop. Roll up doors for delivery trucks are shipped, bolted to these sheets, and are thrown away, once the d oors are installed.
The filaments are in series, not parallel. The audio output tube is 3V, as well.
I'm not the only person who needs one of these. That was why I bought ten reels of the transformers. They were only 1.5 cents each, delivered.
snipped-for-privacy@highlandsniptechnology.com wrote in news: snipped-for-privacy@4ax.com:
NEDA 200 67.5 volt batteries were common.
He wants 90 volts. I was wondering how much current.
There were 90 volt batteries too. I think they were expensive. My 1965 Allied catalog shows pricing from $2.97 for a small one to $8.90 for a big one.
What's the multiplier from 1965? About 8:1?
-- John Larkin Highland Technology, Inc lunatic fringe electronics
Yes, I had one like that, battery eaters... MW AM only...
If you think in watts anodes all together about 150 mA 90 V -> 13.5 W. Heaters 2.8V 150 mA 3 tubes? 2.8 V 450 mA -> 1.26 W. Together say 15 W, Converter efficiency 75 % -> total 20W..
Earhlings have one universal voltage on their planet: 12V (10-15). Most cars have it and every country sells a wallwart for it ;-). I would install a 12 V socket.. Convert up to 90V and down to 2.8V.
12 V 20 W would need a say 12V 2A wallwart. 12 turns primary Maybe 3 turns for the heaters..The 12V switch-off would give about 70- 90V flyback peak, add some turns to make it a bit more. Fast Si diode for the HV (no Schottky).
As to the size of the E | core, for 20 W you need some real size, think like a small transistor TV line output transformer core.
Seems a fun project, but from a historic POV when transistors arrived I never looked back...
Yes OK, but see my other post for the power calculation.
Getting re-acquainted with toobz is just a bit of hobbyist fun, Jan. And it *is* fun, too. Try it!
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PS to keep that MW band clear you could use a sinewave based converter, maybe drive push-pull, and just use an extra 90 - 12 = 78 turns for the HV. ringcores... ebay module?? Here a simple high power 12V converter with 2 old ring cores driving those a bit into saturation here, but with less load it gives a nice sinewave mine on the left, big ebay RF heating module on the right, 2 power MOSFETs push pull, 50 W:
There are many ways to do this,
HV.
ice sinewave
s push pull, 50 W:
6109.JPGThe filaments are series. 9VDC at 50 mA, for a .45W load.
9.5+3.0+6.0+6.0+0.5 = 25 mA maximum plate currents = 2.25W max load for the 90V supply. It is lower in actual use, of course.These tubes are directly heated, not separate cathode types.
I am looking at using common rechargeable 18650 Li-ion Batteries. Three, in series to power the inverter, and a LDO regulator for the filaments.They w ill fit in the available space, Maybe even a double or triple set to extend the usable time between charges? Line the inside of the box with steel she et metal to add weight and provide for fire protection? Unfortunately, the only metalworking company near here recently closed. I could have had metal boxes custom stamped for under $10 each.
Try 9V at 50mA, or 0.45W
Maximum plate load is only 2.25W
The filaments are 9V, not 2.8
The radio already has a 120VAC power supply, why would you want a wallwart?
I have: 5000 - Vishay HER105-T
For less than 3W?
Tubes appreciated that, from you. :)
That is exactly the same as the European DL92 series I gave a link to.
OK then, seems like you have a different radio than I had.. Also I thought you wanted mains power and not batteries, but you want batteries and not mains. Li-ion works, but fire hazard, lifepo4 is safer but has less capacity. My experience with Lipo is better than li-ion for drones that is (at about 70 W load), I have 3 cell lipos for my RC plane, nominal about 11.1 V 2200 mAh.
2 cell Lipos for my Hubsan drone, 7.4 V nominal, bit low for the heaters.. I am moving everything else apart from the flying stuff here to lifepo4.The alternative would be to buy a standard DC to AC converter.. ebay
Back to my ringcore 12 V to ?? converter, it has about 100 kHz sine out, mmm that is in the long wave band, and an harmonic every 100 kHz in the MW band ;-) if you must keep heaters separate some extra turns..
It is probably possible to do it at 2 MHz above MW, but I never tried, it needs RF ringcores for that. Interesting project :-)
Have you considered the cathode potential difference due to the series-connected filaments?
-- -TV
,
the HV.
a nice sinewave
FETs push pull, 50 W:
IMG_6109.JPG
for the 90V supply. It is lower in actual use, of course.
, in series to power the inverter, and a LDO regulator for the filaments.Th ey will fit in the available space, Maybe even a double or triple set to ex tend the usable time between charges? Line the inside of the box with steel sheet metal to add weight and provide for fire protection? Unfortunately, the only metalworking company near here recently closed. I could have had m etal boxes custom stamped for under $10 each.
The fact that over a quarter million of these were built and sold would sho w that it was considered by the OEM. These tubes (1L5, 1U4, 1U5, 3V4) were designed to be used in this way. As long as the individual grids had the pr oper bias, why would it matter? These were first designed prior to WW II, i n the early days of 20% components.
?? Surely 6.3V?
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Not in a portable radio. There are four 1.5 and one 3V filaments, in series. The battery was 9VDC filament, and 90VDC for the Plate supply, and they were Carbon Zinc.
Michael Terrell wrote in news: snipped-for-privacy@googlegroups.com:
My radio handset had 3 inch long raytheon vacuum tubes in it. A whole array of little tiny tubes wired up in there.
I wish a I still had them. I had a pair.
I recall using those during the 1970s in some WW2 radio.
For less current, you can zig-zag ten 9V batteries together, just snap each one to the next one.
Ah! Thanks for the clarification.
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