Yes, they are directly heated, but ordinary tubes. 4P1L are exceptional tubes, super linear!
Yes, but there were some very linear sweep tubes used in radar displays: British VT127/CV1127 and Soviet version 4П10С (4P10S).
I am enjoying at home a version of my 2x6W Edelweiis-3 amp that runs 4P10S tubes. Gorgeous!!!
Not sure about the availability of the valve types in the USA but here in the UK the few I found on the list are more expensive than your average audio OP valve. They aren't available in any quantities either. Is there a supplier in Europe that anyone knows of, or a US supplier that sells for a competitive price? If not once shipping and customs/post office fees are taken into account, doesn't look like TV horizontal sweep valves offer much of a saving.
The more common types like PL509's, 6DQ6 etc have rocketed in price here in the UK recently and are getting harder to find at a good price.
Andy.
The more common types like PL509's, 6DQ6 etc have rocketed in price here in the UK recently and are getting harder to find at a good price.
Andy.
6P13S's and 6P31S's not a same tubes. Different parameters and different sound.Unfortunately I don't understand the Russian language...
What was the voltage you were using? I've been running 36LW6 in push pull tride 120ma @320V with no issues so far. Same setup with 6P45S without issue.
These tubes were used in a modified TSE amp which was connected to my PC and driving my Yamaha NS10's. It was on a lot, and sat idle for a good percentage of the time. The tubes were run in SE class A and the first two were set to 100 mA of idle current. The last two were set lower, but I don't remember exactly where.
I started at just over 400 volts and worked my way down to about 325 volts as tubes blew up. Oddly there seemed to no correlation to voltage VS lifetime. The first tube lasted almost a year at maybe 420 volts. The second tube blew in a couple of months at around 385 volts. Same power supply, just swapped the 5AR4 for a 5U4. Then I swapped the power transformer to get me in the 360 volt range, and later swapped rectifiers for about 330 volts.
All died the same death. At first the idle current would start creeping upwards, requiring periodic bias readjustment, which became more and more frequent. Then one day the tube would go into red plate runaway. Two failures were smashed to look for clues, but none were found.
The other two are in the picture.
The Sylvania went red plate when I wasn't in the room and it eventually blew the line fuse. It cooked itself enough to look fried, and does not run away today if used, but it has near zero emission.
The fat bottle GE was the first to die. After nearly a year of good service, it got the blue glow of death one day, red plated, and caused the amp to hum at which point I shut it off. I suspected a minor air leak, so I kept the tube to see if the getter eventually turned white or disappeared. It still looks good after nearly 10 years, but the tube will ionize a bright blue glow today even without heater power. Something inside the tube outgassed some conductive ions, probably a glowing screen grid.
I have been experimenting with a unique new way to make sweep tubes work like big triodes. I have it working with P-P amps, but SE is still a challenge. Once the redesigned TSE board is finished, there will be some serious sweep tube SE experiments. I have over 100 25DN6's that I got for under 50 cents each for "testing."
H-sweep work is VERY different from linear audio.
First: the distinction Center and Max is well documented. Tubes and parts vary. If you just throw stuff together and ship it, the Center spec leaves margin for typical tolerances. If you measure every set you build, or have effective regulation to limit tolerance shift, you may use the Max spec.
BUT: the real problem when selling tubes for sweep duty is that they swing from HIGH current to HIGH voltage, and it is very hard to know the actual dissipation (before computerized measurement tools). Very small shift of tolerances can cause large increase of dissipation. If drive level falls off, or coils get leaky, dissipation can double. The Pdiss specs on most sweep tubes are very conservative for medium current/voltage operation that does not slam to extremes.
Against that is the fact that H-sweep tubes had to be beefy but also as cheap as possible. Both for OEM and as repair parts. As George's pictures show, the "same" tube could be built differently, probably depending some on market pressure and warranty policy. Tubes sold on 30-day warranty might be cheapened to just barely live 31 days.
Unfortunately I don't understand the Russian language
Don't you understand anode curves?
I miss 38HE7 and 38HK7 / 53HK7 which are both booster diode plus horizontal sweep in a single compactron bottle
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