Hi this is my first post at this forum so be gentle...
I am currently renovating some old tubegear and came across a strange tube.
Its broken so I need to replace it but the problem is that I dont know what it is..
Its marked:
G1S11
"STANDAR"
"SVENSK TILLV"
And inside the tube its painted in white "HT 49"
Its like 3" tall and 1" in diameter
The internal structure is made of two small steelpins and something that looks like a heaterwire with a thin wire around it. But the wire is burned of so its broken.
What is this tube?
It could be a lamp.... But what if its not?
Included is a poor scan if it..
I am currently renovating some old tubegear and came across a strange tube.
Its broken so I need to replace it but the problem is that I dont know what it is..
Its marked:
G1S11
"STANDAR"
"SVENSK TILLV"
And inside the tube its painted in white "HT 49"
Its like 3" tall and 1" in diameter
The internal structure is made of two small steelpins and something that looks like a heaterwire with a thin wire around it. But the wire is burned of so its broken.
What is this tube?
It could be a lamp.... But what if its not?
Included is a poor scan if it..
An externally hosted image should be here but it was not working when we last tested it.
Hi,
It is probably a balast tube or "barett", it is constant current device that is used in series heater chains to take care of additional voltage drop. It consist of a iron wire in hydrogen gas, when the iron wire heats up the resistance is increased so the current goes down, the iron wire gets cooler aso until it reaches a equilibrium where the current is almost constant.
Regards Hans
It is probably a balast tube or "barett", it is constant current device that is used in series heater chains to take care of additional voltage drop. It consist of a iron wire in hydrogen gas, when the iron wire heats up the resistance is increased so the current goes down, the iron wire gets cooler aso until it reaches a equilibrium where the current is almost constant.
Regards Hans
baretter
It's not so much the voltage drop, as the heater chain current you are interested in. Check the heater current of the valves by looking up their spec's at Frank's tubes . It'll be in the region of 100 to 200mA I think. Then add up the total heater voltage (the valves will be in series). now do some calculations....
You can also do soeme google research using the keywords: baretter & balast
It's not so much the voltage drop, as the heater chain current you are interested in. Check the heater current of the valves by looking up their spec's at Frank's tubes . It'll be in the region of 100 to 200mA I think. Then add up the total heater voltage (the valves will be in series). now do some calculations....
You can also do soeme google research using the keywords: baretter & balast
It is not recommended to replace it with a resistor as a balast is a constant current device. The current value of the original barett is dependant on what kind of tubes that are used, U series tube are for 100mA and P series for 300mA.
Depending on the number and type of tubes type in the heater chain the voltage drop can be quite substantial so it is not so easy to replace it with a series resistor. Try to search for the tube data in TDSL and calculate the total voltage drop, then you can calculate the drop in the barett and design asimple constant current solid state replacement.
A problem with using a solid state replacement is that the heaters normally are connected to AC voltage but maybe you can rectify the AC with a simple bridge rectifier so you can use a solid state constant current circuit, this can be simple as no great accuracy is needed, a transistor, a few diodes and a few resistors should be enough.
Regards Hans
Depending on the number and type of tubes type in the heater chain the voltage drop can be quite substantial so it is not so easy to replace it with a series resistor. Try to search for the tube data in TDSL and calculate the total voltage drop, then you can calculate the drop in the barett and design asimple constant current solid state replacement.
A problem with using a solid state replacement is that the heaters normally are connected to AC voltage but maybe you can rectify the AC with a simple bridge rectifier so you can use a solid state constant current circuit, this can be simple as no great accuracy is needed, a transistor, a few diodes and a few resistors should be enough.
Regards Hans
No...
When I took a closer look I realised that they wherent.
The 6L6 where wired in paralell and the only tube wired in serie with the ballast tube was the 6SJ7.
I was at work so I didnt have the thing in front of me... Never jump conclutions
But now I had time to really study the design.
There is a 12,6v winding going to the ballast tube and then to the 6sj7 so thats why there is a ballast tube so that the 6sj7 has the right heater voltage and current I think
But I dont understand why there is a ballast tube to begin with?
There is 6,3v windings at the main trafo..
When I took a closer look I realised that they wherent.
The 6L6 where wired in paralell and the only tube wired in serie with the ballast tube was the 6SJ7.
I was at work so I didnt have the thing in front of me... Never jump conclutions
But now I had time to really study the design.
There is a 12,6v winding going to the ballast tube and then to the 6sj7 so thats why there is a ballast tube so that the 6sj7 has the right heater voltage and current I think
But I dont understand why there is a ballast tube to begin with?
There is 6,3v windings at the main trafo..
As I understand from your description the tube only have a few volts over it, in that case it is not a balast tube as those need in the order of 50 - 150V to work as intended. My guess is that it is a light bulb and it could be in the circuit in order to drop the heater voltage to the 6SJ7 tube.
BTW, the purpose of this "strange tube" in this circuit is not at all to slow the heater turn on, a balast or light bulb have very low resistance at turn on so the effect is opposite, the tube in series get higher voltage then it would get if it was connected directly to the heater winding.
It would help to understand the function if you can describe the circuit in more detail, can you post a circuit diagram?
Regards Hans
BTW, the purpose of this "strange tube" in this circuit is not at all to slow the heater turn on, a balast or light bulb have very low resistance at turn on so the effect is opposite, the tube in series get higher voltage then it would get if it was connected directly to the heater winding.
It would help to understand the function if you can describe the circuit in more detail, can you post a circuit diagram?
Regards Hans
No sorry I dont have a schematic but I can backtrace the hole thing.. It might take some time...
But now to another problem.. I replaced the "ballast" tube with a 22ohm resistor and started the thing. Had to replace two of the 6L6 tubes but it seems to work.
The gear is a adjustablepowersuply unit and it shall give out up to 300v 300mA maximum.
But mine doesnt... When I turn on the heaterswitch it gives out 155v at the output when I think it should give out 0v. Bare in mind that the anodswitch is not turned on at this time.
When I then turn on the anodswitch the output raises to 205v and is adjustable up to like 400v... Way to much compared to what the sign says.
What can be wrong? I have tested all the tubes with a simple tubetester and there seems to be no internal short... I cant test for short when the heater is turned on whit this tubetester.
is this a sign that its time to switch tubes?
But now to another problem.. I replaced the "ballast" tube with a 22ohm resistor and started the thing. Had to replace two of the 6L6 tubes but it seems to work.
The gear is a adjustablepowersuply unit and it shall give out up to 300v 300mA maximum.
But mine doesnt... When I turn on the heaterswitch it gives out 155v at the output when I think it should give out 0v. Bare in mind that the anodswitch is not turned on at this time.
When I then turn on the anodswitch the output raises to 205v and is adjustable up to like 400v... Way to much compared to what the sign says.
What can be wrong? I have tested all the tubes with a simple tubetester and there seems to be no internal short... I cant test for short when the heater is turned on whit this tubetester.
is this a sign that its time to switch tubes?
It is off course very difficult to know what is wrong but have you loaded the power supply when you measured the voltage? Some power supplies need a small load in order to work correctly. If it gives DC volage out only with heater voltage on it could be so that you see a result of leakage current only.
As electronic power supplies usuallay are quiet simple it should be quite easy to find the fault if any, start by measuring the voltage on the grid of the series regulator tube, in your case probably a 6L6, this voltage must be close to 0V or a few volts below in order to get 0V out.
Another cause of fault I can think of is that the negative voltage supply doesn't work, there must be a negative voltage supply some where as the output voltage should be possible to regulate down to 0V otherwise this wouldn't be possible.
Regards Hans
As electronic power supplies usuallay are quiet simple it should be quite easy to find the fault if any, start by measuring the voltage on the grid of the series regulator tube, in your case probably a 6L6, this voltage must be close to 0V or a few volts below in order to get 0V out.
Another cause of fault I can think of is that the negative voltage supply doesn't work, there must be a negative voltage supply some where as the output voltage should be possible to regulate down to 0V otherwise this wouldn't be possible.
Regards Hans
- Status
- This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.