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[Amps] Hombrew 3-1000Z in SA

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Subject: [Amps] Hombrew 3-1000Z in SA
From: Patrick Barthelow <>
Date: Thu, 13 May 2010 16:36:29 -0700
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As most of you have read, I am seeking an amp for a friend in Uruguay, via 
almost any mechanism that is minimal cost.  Basket cases, tubes, parts, 

Come to the conclusion that most has to be found, or originate in country, due 
to very stiff duties (apparently ~100% of new paid value) paid, or shipping 
costs for heavy items.


I wonder if duties can be waived or reduced if bring in is accompanied, with a 
strong letter of endorsement by the national Amateur Radio Body, explaining the 
emergency comms, public service aspects of amateur radio. with reference to the 
specific person receiving the item?


I found a single  3-1000Z nicely built amp with separate power supply, now for 
sale by family of an SK ham in Uruguay.    

Has not been powered up for at least 2 years, when the SK ham passed away.


See Photos:



I love the big bottles, but dont know any specific  gotchas on the 3-1000Z.  
So, looking for exprienced feedback on the  3-1000Z. :
1. Are 3-1000Zs  prone to failure due to gas intrusion through the glass/metal 
seals, with dormancy/non use,  like the 3-500Z?
2. Can an old stored 3-1000Z be rejuvinated in the usual way, burn in, low B+ 
gradual increase, getting the plate hot?
3.  What is the availability of replacement 3-1000Zs New or used?
4.  If this is the last practicaly obtainable 3-1000Z in the country,   what 
modern external anode triode might be a electrically similar tube, using 
similar B+ and having similar Plate Z in amateur operation,  that could be 
swapped (with rebuild, redesign of the tube mount, and fil transfomer change) 
into the amp if this 3-1000Z fails?   (maybe the GS-35B?) 
5. Is it a good idea to design a filament cold start circuit, or perhaps a 
small variac to bring the filament voltage on to try to get maximum years out 
of the tube?
I think I remember a 7.5 V  21 Amp fil requirement.  Pretty good THUNK!  when 
you turn on filaments, I bet.


6. Can 100 watts input drive them to Legal Limit?  With a tuned input?  Without 
a tuned input?  


7. What is the input Z if direct fed, without a tuned input circuit?


Thanks for all  your prior valuable input.

Best Regards,   
73, de Pat Barthelow AA6EG

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