[Amps] grid fuses

[Will Matney]

Tom,

I hate to come out and say this, but if you don't think this is the way grid leak bias was derived and used in the past, your just plainly quite wrong. It's been used in transmitters and receivers before the 40's that I know of. I can show proof over and over again if anyone has any of the old Rider or Sams manuals on tube radios. I can also show proof of this very same circuit in schematics here on the net for either sweep tube amps, and other types of equipment (some by the ARRL staff if I recall). Matter of fact, it was taught in the military training manuals (I have an Air Force copy, and the NEETS books show it too). It may not have been used in some amateur amps of a larger size, but it was in the small amps, transceivers, transmitters and receivers. Also, anyone who thinks the control grid in a power tube cant be negatively charged with electrons is dead wrong. Quote; "Don't hang your hats on that as something justify gross misstatements that the grid in a large power grid tube will go negative when floated"! Any vacuum tube with a conductive grid can gain a charge of electrons if placed in their path between the cathode and anode. It may not be a good idea to try and use this for bias, but it surely doesn't stop the fact that the grid will obtain a negative charge from the electron flow. Anyone can do an experiment say on a 3-500Z by taking the grid loose from ground and temporarily applying power to the tube while measuring for negative voltage between the control grid pin to ground. You will read a negative voltage here, maybe small, but you'll read one. If this didn't take place, you wouldn't have fluctuations in control grid current when used in circuit. Floating or not, the control grid will be negative, surely not positive. Again, electrons have a negative charge, not positive.

That's all I'll say on this subject.

Will

*********** REPLY SEPARATOR  ***********

On 7/22/06 at 11:04 PM Tom W8JI wrote:

>>>Actually both of you are mixing applications and very
>>>different systems. Contact bias or space charge biasing is
>>>NOT the same as grid leak biasing.
>>
>>
>> No, this actually forms the basis for grid leak biasing 
>> where the grid collects electrons.
>
>Well, I can copy and post authoritative text in several peer 
>reviewed textbooks written by well known authors that 
>disagrees with your claims Will...but I doubt it will do 
>much good.
>
>I guess we will just have to agree to disagree on this one 
>also.
>
>73 Tom 
>
>
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