[Amps] Hi Mu correction

Tony King - W4ZT amps071806 at w4zt.com
Wed Jul 19 17:51:46 EDT 2006


Thanks Bill, I think that is the best explanation I have seen.

73, Tony W4ZT

Bill Fuqua wrote:
> Lower mu tubes have wider spacing between the grid wires allowing more 
> electrons to slip by each second for the same bias voltage. It also 
> reduces the effective control the grid voltage has over the plate 
> current, thus lower mu. You can easily see this difference in grid wire 
> spacing by comparing a 250TH with a 250TL. Or a 811 with a 812.
> 
> 73
> Bill wa4lav
> 
> 
> At 11:55 PM 7/18/2006 -0400, Tony King - W4ZT wrote:
>> Tom W8JI wrote:
>> > I do think I made an error in the post about mu, but I
>> > deleted my post.
>> >
>> > Higher mu in a given tube means less bias is needed to
>> > maintain the same plate current. Lower mu means more bias is
>> > needed to cut off the tube to the same current. The rest was
>> > OK.
>> >
>> > 73 Tom
>>
>> I'm still a little confused here.  I thought that a higher mu tube
>> (higher gain) would require more bias to hold it to a specific current
>> (idle?) and that a lower mu tube (lower gain) would require less bias to
>> hold a specific current.  Can you help me understand where I am missing
>> this?
>>
>> Thanks and 73,
>> Tony W4ZT
>>
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> 


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