A "screen " is usually designated as G2 that's very common in radio work and as the tube is used for HF communications instead of being automatically connected to the cathode G3 as a GRID its separate as special communications equipment sometimes demand that .
In "triode mode " G2/screen is connected to the plate .
Grid 3 is a "suppressor grid " and usually tied to the cathode to keep high speed electrons from bouncing off the plate on impact.
In "triode mode " G2/screen is connected to the plate .
Grid 3 is a "suppressor grid " and usually tied to the cathode to keep high speed electrons from bouncing off the plate on impact.
by the way, not sure what you are building, but the 6e6p - DRY is a SUPERB headphone driver. 180v, 30 to 35ma, 2.4v cathode bias through SIC diodes. I honestly prefer it to the now hideously expensive d3a. Mu is less, but we dont need the extreme of the d3a in this instance. The odd one is microphonic, but same for d3a. Biggest drawback is the heater current, datasheet says 500ma, i measure nearer 600, so they are thirsty, and get hot.
Wanted to swap the 2 types with a minimum of changes
I can change the bias easily using one of Ale Moglia's SiC boards. So what I need to know is can I connect pin 8 of the 6e6 to the top of the cathode. I believe the data sheet says to connect to a considerably lower potential, so is the 3.5 volt bias low enough?
Alternatively if pin 8 is grounded will it be a problem for the E180F, which has internal screen/g3 at that position? Sorry if I did not make myself clear before
I can change the bias easily using one of Ale Moglia's SiC boards. So what I need to know is can I connect pin 8 of the 6e6 to the top of the cathode. I believe the data sheet says to connect to a considerably lower potential, so is the 3.5 volt bias low enough?
Alternatively if pin 8 is grounded will it be a problem for the E180F, which has internal screen/g3 at that position? Sorry if I did not make myself clear before
pin 8 on 6e6p should be grounded, and probably will not be ok grounded for the e180f.
Two options - when swapping remember to desolder and move other option is create something like my attempt with small switches. When i settle on the final design, that whole board will be ripped out and i will point to point the final design (removing pots, bias selector, pin 8 switches). Currently that is more likely to be with the 6e6p dr version, not the d3a version.
Two options - when swapping remember to desolder and move other option is create something like my attempt with small switches. When i settle on the final design, that whole board will be ripped out and i will point to point the final design (removing pots, bias selector, pin 8 switches). Currently that is more likely to be with the 6e6p dr version, not the d3a version.
E180F is a "real" pentode, has three grids.
The third grid (Pin 8) is working also as screen.
6E6P (DR) has only two grids, and one conductive layer as screen (Pin 8).
https://i2.wp.com/www.bartola.co.uk/valves/wp-content/uploads/2013/02/6E6P-DR.jpg
In triode mode -in both cases- the second grid (g2) connected to anode (with resistor as Key wrote), the third (or screen) connected to the most lower potential of the tube, to the cathode.
The third grid (Pin 8) is working also as screen.
6E6P (DR) has only two grids, and one conductive layer as screen (Pin 8).
https://i2.wp.com/www.bartola.co.uk/valves/wp-content/uploads/2013/02/6E6P-DR.jpg
In triode mode -in both cases- the second grid (g2) connected to anode (with resistor as Key wrote), the third (or screen) connected to the most lower potential of the tube, to the cathode.
The pinout for this is nearly identical to a triode strapped 6E6P-DR. With the latter pin 8 goes to ground. The E180F pin 8 has a screen and g3, does it need to connect to the cathode pin or is it ok to connect to ground? Thanks for your help
Since you only asked for g3: I still suggest you connect it to k or a and do a listening comparison.
6E6P is an output tetrode like many power tubes , but for HF that's why it has a shield at pin 8 to be connected to ground as usual ...
This has nothing to do with a small signal pentode as E180F where G3 & shield is usually connected to cathode . But there is not much difference if the cathode is a few volts above ground .
This has nothing to do with a small signal pentode as E180F where G3 & shield is usually connected to cathode . But there is not much difference if the cathode is a few volts above ground .
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Data for 6688/E180F as triode
The June 1961 Amperex data sheet for the triode connected 6688/E180F shows grid 3 (pin 8) connected to the cathode (pins 1 and/or 3) and grid 2 (pin 9) connected to the anode/plate (pin 7).
For Vak = 151V and Vgk = 9V, ia = 16.5mA, gm = 18.5 mS, mu = 50, rp = 2700 Ohms.
The same data is in the original 1956 Rogers Electronics registration papers for the 6688.
Some years ago Richard Sears kindly published measured anode curves for the triode connecected 6688/E180F (here: http://www.triodeguy.com/Triodeguy PDF files/6688 Triode Curves RFS Measurements.pdf)
The June 1961 Amperex data sheet for the triode connected 6688/E180F shows grid 3 (pin 8) connected to the cathode (pins 1 and/or 3) and grid 2 (pin 9) connected to the anode/plate (pin 7).
For Vak = 151V and Vgk = 9V, ia = 16.5mA, gm = 18.5 mS, mu = 50, rp = 2700 Ohms.
The same data is in the original 1956 Rogers Electronics registration papers for the 6688.
Some years ago Richard Sears kindly published measured anode curves for the triode connecected 6688/E180F (here: http://www.triodeguy.com/Triodeguy PDF files/6688 Triode Curves RFS Measurements.pdf)
Thanks for the info
I really appreciate that info. I tried biasing with 2 SiC diodes and ended up with about 185 volt at the plate and 1.75 volts bias, about 15 ma. I have quite a few of these and they are pretty consistent. The 6E6 is inconsistent but initial impressions are that I prefer the 6e6 Will give it a few more hours before making up my mind
I really appreciate that info. I tried biasing with 2 SiC diodes and ended up with about 185 volt at the plate and 1.75 volts bias, about 15 ma. I have quite a few of these and they are pretty consistent. The 6E6 is inconsistent but initial impressions are that I prefer the 6e6
Will give it a few more hours before making up my mind- Status
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