Searched and found nothing on these interesting fellas. The diagram in the datasheet seems to indicated that the diode plates lie in between the cathode and the control grid. As such how would you handle the diodes if you are not using them. I wouldn't want them to strip off electrons nor would I necessarily want to turn it into a space charge tube (although that might be interesting) yet it is generally considered bad form to have elements floating. Can one simply ground them?
If you keep the cathode at 0 Volts or positive volts with respect to ground (like in self bias), then connect the diode plates to ground.
If the cathode is negative with respect to ground, then tie the diode plates to the cathode.
If the cathode is in a circuit that could sometimes be negative with respect to ground, and sometimes be positive with respect to ground, then connect the diode plates to the cathode.
That should take care of the problems that could occur with floating elements.
If the cathode is negative with respect to ground, then tie the diode plates to the cathode.
If the cathode is in a circuit that could sometimes be negative with respect to ground, and sometimes be positive with respect to ground, then connect the diode plates to the cathode.
That should take care of the problems that could occur with floating elements.
The triode in the aBCx1 is essentially half a 5751. Unused diodes should be connected to the cathode.
Thanks guys. Just wasn't sure if the diode plates would interfere with grid action. You would think that it would have been designed with that in mind.
Look at the 12AV6 tube, a dual diode and triode combination.
Most drawings of the position of the elements will show the true nature of that kind of tube.
The diagram for the UBC41 was a very poor way to draw the placing of the elements.
It makes you wrongly assume that the diode plates are in the way of the triode grid and triode plate; they are not.
Most drawings of the position of the elements will show the true nature of that kind of tube.
The diagram for the UBC41 was a very poor way to draw the placing of the elements.
It makes you wrongly assume that the diode plates are in the way of the triode grid and triode plate; they are not.
If you mean Fig 2 in the datasheet, then ignore it. It is quite misleading. The diode anodes use their own part of the cathode, so no interference with the triode operation.
Some similar valves, such as 6AT6/EBC90, don't have a screen/shield so you can see where the electrodes are.
I have been using the 6Q7, 6SQ7, 6AT6, 6AV6, 6AQ6 18FY6 family of double diode - triodes for over 50 years. I don't connect the diodes to anything and have never had an issue. They will collect enough electrons to bias themselves a few volts negative and then do nothing.
This negative voltage can not be measured with a modern digital meter since the meter's input resistance will bleed off the charge. You can prove this by connecting a capacitor to the unused diode and measuring the voltage with a VTVM or other high impedance meter.
I vaguely remember about 4 volts from a 6SQ7 but it has been 50+ years since those days.
Ground them, wire them to the cathode, or do nothing, it's your choice, and sometimes dictated by the layout. Often excess ground around the base of a high gain triode stage can by a friend.
This negative voltage can not be measured with a modern digital meter since the meter's input resistance will bleed off the charge. You can prove this by connecting a capacitor to the unused diode and measuring the voltage with a VTVM or other high impedance meter.
I vaguely remember about 4 volts from a 6SQ7 but it has been 50+ years since those days.
Ground them, wire them to the cathode, or do nothing, it's your choice, and sometimes dictated by the layout. Often excess ground around the base of a high gain triode stage can by a friend.
Magnavox used the 6AT6 in their model 150 monoblocks. I have a couple of them. The diodes are not connected to anything.
I once had a Stromberg Carlson integrated amp that used a 6AT6 or 6AV6 it also left the diodes unconnected. When you are paying assemblers to PTP wire a chassis on an assembly line extra soldering operations cost money, and provide opportunities for mistakes.
We are free do do as we choose with our DIY one-offs, but I minimize extra connections because a lot of my stuff never works, and thus gets saved for reuse or cannibalization. I have a prototype amp now that started out as 3 pieces of junk from my "box of broken dreams."
We are free do do as we choose with our DIY one-offs, but I minimize extra connections because a lot of my stuff never works, and thus gets saved for reuse or cannibalization. I have a prototype amp now that started out as 3 pieces of junk from my "box of broken dreams."
If you want to use the diodes, remember . . .
The diode Plates are only useful in a circuit if you also use the Cathode for that part of the circuit.
What ever the cathode voltage is, versus the Diode Plate voltage, will dictate whether the Diode conducts or not.
These were normally used in superheterodyne radios, one diode as the AM detector, one as an AGC detector (for Automatic Gain Control of earlier stages in the radio).
Since the triode section was often used (with self bias on the cathode) as the first audio stage in that radio, that dictated whether the diode plates could be used in any given circuit or not.
I believe they sometimes also were used in the FM Detector circuits of FM radios too.
We do not always have to use all the elements that are contained in the same glass envelope of a single tube.
The usefulness of those diode plates are only limited by the genius of the designer (and the maximum voltage and maximum current specs of those diodes).
The diode Plates are only useful in a circuit if you also use the Cathode for that part of the circuit.
What ever the cathode voltage is, versus the Diode Plate voltage, will dictate whether the Diode conducts or not.
These were normally used in superheterodyne radios, one diode as the AM detector, one as an AGC detector (for Automatic Gain Control of earlier stages in the radio).
Since the triode section was often used (with self bias on the cathode) as the first audio stage in that radio, that dictated whether the diode plates could be used in any given circuit or not.
I believe they sometimes also were used in the FM Detector circuits of FM radios too.
We do not always have to use all the elements that are contained in the same glass envelope of a single tube.
The usefulness of those diode plates are only limited by the genius of the designer (and the maximum voltage and maximum current specs of those diodes).
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These tubes were used in radio receivers in the audio section either just before a 6V6G or a much lower output direct .
The diodes were used for AVC /signal , the 6Q7 was also a AF tube and would have a tube line up ( in the UK ) of -
6K8=FC.
6K7=IF.
6Q7-AF.
6V6G=Audio output.
5Z4G= FW rectifier .
The diodes were used for AVC /signal , the 6Q7 was also a AF tube and would have a tube line up ( in the UK ) of -
6K8=FC.
6K7=IF.
6Q7-AF.
6V6G=Audio output.
5Z4G= FW rectifier .
The diodes phsically aren't within the Triode section, but mounted above it instead. Have a look at the following pic of a EBC91, same tube in a 7 pin miniature envelope (courtesy of Wikipedia):
Elektronenrohre – Wikipedia
Best regards!
Elektronenrohre – Wikipedia
An externally hosted image should be here but it was not working when we last tested it.
Best regards!