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
------------------------------------------------------------------
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
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