[Amps] Drake L4 tube replacement

[Jan Erik Holm]

Did surf the inet a bit. Found 3-400Z at www.tubedepot.com
for $279.95, dont know if they still have them but maybe.
Also 4-400A´s and even 4-250A´s could be used however sreen
and grid has to be tied together and if there is any zener
diode bias in the L-4 it has to be removed, i e cathode has
to be grounded directly in order to get decent operating point.
Also I tend to remember that one L-4 I saw did use "open chimneys",
i e same diameter top and bottom, but my memmory could be wrong,
if so ofcourse it makes it easier to drop anything in there.

73 Jim SM2EKM
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Jason Buchanan wrote:
> Jan Erik Holm wrote:
> 
>> Yes! Just like when you run out of gas in your
>> car, just put new in.
> 
> 
> 
> Well, the consensus is that I need to find new chimneys to use the 
> 3-500Z on account of the 3-400Z is a shorter tube.
> 
> There appear to be 3 different chimneys - SK 406 (4.75" tall), SK 406A 
> (4.25" tall) and SK 406B (4" tall).  Sounds like the 3-500Z chimney in 
> use with the L-4B would be the 4.75" SK 406 chimney - the question 
> becomes whether the 4.75" chimney will fit in the older L-4.  I haven't 
> seen any 3-400Z tubes for sale anywhere so it seems that the 3-500ZG 
> types that are available today are the only option for replacement, and 
> they require the tall 4.75" chimney.  "Cooling" is good so I don't want 
> to skimp just to get by with the wrong sized chimney.
> 
> Ron W2CQM has piqued my interest with the 8877 retrofit but my uncle and 
> grandfather would tar and feather me for hacking this L-4 - this amp 
> part of the family!! hi hi
> 
> 
> 73 Jason N1SU
>