Tube DIY Asylum

Do It Yourself (DIY) paradise for tube and SET project builders.

Return to Tube DIY Asylum

Message Sort: Post Order or Asylum Reverse Threaded

Type 10 grid resistance values

45.72.135.73
Posted on October 23, 2016 at 06:57:43
vetmedrobert@gmail.com
Audiophile

Posts: 453
Location: Ontario
Joined: September 20, 2007
 I've looked at all the data sheets on Frank's web site and no mention of resistance values for fixed or cathode bias. If anyone knows please let me know. TIA

 

Hide full thread outline!
    ...
RE: Type 10 grid resistance values, posted on October 23, 2016 at 12:25:07
thermionic addictions
Audiophile

Posts: 894
Joined: June 16, 2006



This sheet shows three different self-bias resistor values. If you want to calculate your own the formula is simply, desired bias divided by plate current. For example, using the 425V sample on the sheet 40V/.018mA = 2222,22 ohm which you would round off to the nearest available resistor value.

Cal

 

Tube Curves, posted on October 23, 2016 at 12:47:05
Chip647
Audiophile

Posts: 2652
Location: The South
Joined: December 24, 2012
 This is one use of tube curves.

Say you want 250 volts on the plate and 10mA of current. The sheet has both a little table for this and the tube curves. The tube curves have the information to construct a table of what ever operating conditions you care to explore. Then you can look at the curve to make sure it is in its linear operation.

So, 250 volt plate and 10mA says -23.5 Volts on the grid (Grid to cathode voltage)

Since Ohm tells us that I = V/R , you solve for R with the simple R = V/I transformation (algebra) so R = 23.5 / 0.01 This gives R = 2,350

Another setting is 450 18mA and -40 R = 40 /0.018 or 2,222 ohms

 

RE: Type 10 grid resistance values, posted on October 23, 2016 at 14:00:05
vetmedrobert@gmail.com
Audiophile

Posts: 453
Location: Ontario
Joined: September 20, 2007
 I guess I did not express myself very well, I would like to know the maximum recommended resistance values for self or cathode bias, or grid bias supply. These are often in the order of 500 kilohm for cathode resistance and 50 kilohm to 100 kilohm for grid supply. I do not seem to see any such values in any of the 10 data sheets I have looked at.

 

RE: Type 10 grid resistance values, posted on October 23, 2016 at 14:01:45
Paul Joppa
Industry Professional

Posts: 7296
Location: Seattle, WA
Joined: April 23, 2001
 Correct me if I'm wrong, but I think the original question was about the grid-to-ground resistance. The question arises because the Type 50 has such limitations - in the specs I have, Sylvania says nothing, Cunningham says "not recommended for RC coupling," and RCA says "... any conventional type of input coupling may be used provided the resistance added to the grid circuit by this device does not exceed 10000 ohms."

I can't find any Type 10 data sheet with a similar condition, but the 10 is an older tube than the 50, and the necessity of this caution seems to have appeared with the 50 (hence the inconsistent data sheet advice). I speculate that in older designs transformer coupling was much more common.

I will note that the requirement is there to limit bias drift through grid leakage current. In that case, the requirement is most severe with fixed bias. For example, the 300B specs from 1950 specify 50K maximum for fixed bias, or 250K for self bias.

 

RE: Type 10 grid resistance values, posted on October 23, 2016 at 14:12:20
vetmedrobert@gmail.com
Audiophile

Posts: 453
Location: Ontario
Joined: September 20, 2007
 Yes, see my second post. I am using a 10 to drive a 10 with an IT. The input 10 is using filament bias so would likely be ok with 100 to 250 kilohm on the grid. The negative bias supply probably would be ok with a resistance of 25 to 50 kilohms. Please let me know if these would be appropriate values, and thanks for your help.

 

Follow Paul's advice., posted on October 23, 2016 at 14:34:13
Chip647
Audiophile

Posts: 2652
Location: The South
Joined: December 24, 2012
 He gave you his best estimate. IMO 100K is fine.

 

Isn't filament bias the same as fixed bias?, posted on October 23, 2016 at 15:47:32
Triode_Kingdom
Audiophile

Posts: 10047
Location: Central Texas
Joined: September 24, 2006
 It doesn't matter whether a negative voltage is applied to the grid or a positive voltage to the cathode, anything other then self-bias with a cathode bias resistor is fixed bias. This is the "most severe" scenario Paul described. If you believe RCA, no more than 10K should be used at the grid.

 

Yes (nt), posted on October 23, 2016 at 19:56:10
Paul Joppa
Industry Professional

Posts: 7296
Location: Seattle, WA
Joined: April 23, 2001
 Yes

 

RE: Type 10 grid resistance values, posted on October 24, 2016 at 00:38:09
Thomas Mayer
Manufacturer

Posts: 602
Joined: May 8, 2001
 Hi!

You can go with the recommended values of the 801A which is very similar. For the 801A 500k for cathode bias is set as max and 100k for fixed bias. Go with 100k or less and you are safe.

I use 100k on the 10 in preamps both with cathode and filament bias and it works reliably

BR

Thomas

 

Page processed in 0.025 seconds.

[ Top Top of Page ] [ Contact Us ] [ Support/Wish List ] [ Copyright © 2024, Audio Asylum, all rights reserved ]
[ General ] [ Speakers ] [ Tubes ] [ Vinyl ] [ Digital ] [ Hi-Rez ] [ Video Asylum ] [ Cables ] [ Tweaks/DIY ] [ Music ] [ Films ]