I've got 8pcs of KT170 with pairing values of "52". But I have no idea what actually the number means.
Noticed that some peoples are complainging about the imcomplete datasheet of KT170. I think I can offer some help for those who're hesitating to try the tube.
Capacitance between electrodes were not menthoned in the datasheet. Here's the major part of capacitance when applied in Triode mode.
Cathode to Grid 1: 25pF
Grid 1 to Grid 2: 18pF
Cathode to Grid 2: 20pF
Values are only for reference, and the accuracy is not guaranteed.
The filament current is about 1.97A±0.1A @ 6.34V at the pins of the tube socket
Here's the curves I've traced with my modified etracer. (The maximum current of HV1&HV2 were modified twice, up to 600mA)[/SIZE]
The current are HIGHER than that in the datasheet.\
For example Vg1=-5V, Va=500V. It's only 300mA according to the datasheet, but it's measured nearly 400mA on my equipment.
When Vg2=250V.
When Vg2=275V. The starting point of Vg1 was adjusted to -3V, since the etracer program can't display current higher than 600mA.
Here's the Triode Mode. The current of Grid2 is about 1/8 comparing with Anode current.
HV1_I is the total current of Grid2 and Anode in the upper picture.
(HV1_I is Anode current, and HV2_I is Screen current. I think such kind of axis can show the ratio between them)
In my own project, I'd like to operate them in Paralleled, Class A Push-Pull. So I don't need a enormously high peak plate current as Class AB Push-Pull. In such conditions, I think using Ultra Linear mode with UL taps much closer to the Plate taps is a good idea. In such working conditions, the characteristics of the tube is more likely to A2 operations of Triode connected. But since the voltage at Grid1 is always minus 0, the driving circuit don't need to have abilities handling grid current.
Here's the curves of my own design. B+ = 440V, with 75% UltraLinear Taps.
Notice that Plate current and Screen current were added together here.
Noticed that some peoples are complainging about the imcomplete datasheet of KT170. I think I can offer some help for those who're hesitating to try the tube.
Capacitance between electrodes were not menthoned in the datasheet. Here's the major part of capacitance when applied in Triode mode.
Cathode to Grid 1: 25pF
Grid 1 to Grid 2: 18pF
Cathode to Grid 2: 20pF
Values are only for reference, and the accuracy is not guaranteed.
The filament current is about 1.97A±0.1A @ 6.34V at the pins of the tube socket
Here's the curves I've traced with my modified etracer. (The maximum current of HV1&HV2 were modified twice, up to 600mA)[/SIZE]
The current are HIGHER than that in the datasheet.\
For example Vg1=-5V, Va=500V. It's only 300mA according to the datasheet, but it's measured nearly 400mA on my equipment.
When Vg2=250V.
When Vg2=275V. The starting point of Vg1 was adjusted to -3V, since the etracer program can't display current higher than 600mA.
Here's the Triode Mode. The current of Grid2 is about 1/8 comparing with Anode current.
HV1_I is the total current of Grid2 and Anode in the upper picture.
(HV1_I is Anode current, and HV2_I is Screen current. I think such kind of axis can show the ratio between them)
In my own project, I'd like to operate them in Paralleled, Class A Push-Pull. So I don't need a enormously high peak plate current as Class AB Push-Pull. In such conditions, I think using Ultra Linear mode with UL taps much closer to the Plate taps is a good idea. In such working conditions, the characteristics of the tube is more likely to A2 operations of Triode connected. But since the voltage at Grid1 is always minus 0, the driving circuit don't need to have abilities handling grid current.
Here's the curves of my own design. B+ = 440V, with 75% UltraLinear Taps.
Notice that Plate current and Screen current were added together here.
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The parameters shown in the graphs are safe working figures. Many valves will cope with far more current but may fail over time.
The number 52 is a figure taken from the testers own equipment and reflect practically no meaning to others except the valves with a 'value' of 52 are all somewhere equal in dissipation / grid voltage.
The KT120 and others are a clone of the KT88 and produced for those wishing to push the limits in my view.
If you consider a KT*** has a dissipation limit controlled by the amount of heat building up on the anode. Keep the anode cool and it will dissipate more power, hence some large power transmitter valves were water cooled.
Give them a carbon anode and the valve will keep dissipating until the glass envelope implodes and I have done that with an 813 many years ago.
The number 52 is a figure taken from the testers own equipment and reflect practically no meaning to others except the valves with a 'value' of 52 are all somewhere equal in dissipation / grid voltage.
The KT120 and others are a clone of the KT88 and produced for those wishing to push the limits in my view.
If you consider a KT*** has a dissipation limit controlled by the amount of heat building up on the anode. Keep the anode cool and it will dissipate more power, hence some large power transmitter valves were water cooled.
Give them a carbon anode and the valve will keep dissipating until the glass envelope implodes and I have done that with an 813 many years ago.
The KT170 has it's screen current trailing off up past 800V plate V (for grid 1 at 0V), while aligned grid tubes drop off to near level by 100V to 200V. Looking at the ratio of plate current to screen current at 200V plate (grid 1 at 0V ) for some various tubes:
KT88 12/1
KT170 7/1
6LW6 24/1
6DQ5 24/1
EL34 7/1
6JA5 25/1
I would say the KT170 does not appear to have aligned grids. Which would explain the rounded plate curves.
KT88 12/1
KT170 7/1
6LW6 24/1
6DQ5 24/1
EL34 7/1
6JA5 25/1
I would say the KT170 does not appear to have aligned grids. Which would explain the rounded plate curves.
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Take a look at the 6HB6 curves for a non aligned beam pentode. Similar, slowly drooping screen current, with a similar 6.4 ratio of plate current to screen current at 200V on the plate. The KT177 however has much nastier looking screen current curves at lower plate voltages. I'm guessing the beam slot is too wide, making it closer to a tetrode. The KT177 needs some re-design work.
https://frank.pocnet.net/sheets/135/6/6HB6.pdf
https://frank.pocnet.net/sheets/135/6/6HB6.pdf
That’s what I was going to say! It’s an almost kinkless or a little kinky tetrode!