>
>I have decided on a new amp (after asking about recommendations here
>recently) - a good friend has a Henry 2K2 desktop amp in excellent cosmetic
>and electrical condition for $600 -
? a bargain, provided you don't mind doing a little updating.
>- I haven't completed the purchase yet,
>so if I'm making a horrible mistake, please tell me now before I plunk down
>my cash!
>
>Only thing that really worries me about it is the 3-400 tubes - they're
>pretty hard to find these days. I understand it's relatively simple to
>convert the 2K2 to use 3-500z's - yes? no?
>
? 3-400Zs and3-500Zs have the same PEP output in SSB or CW service
because peak emission is equal. However, for RTTY service at 4000v, the
3-500Z is a better choice. . Amperex still makes the 3-400Z/8163. I
run a pair in my SB-220 with 0v bias. One was mfg. in 1967. It still
has good emission. // In my experiences, 3-400Zs are mechanically more
rugged than 3-500Zs. I have seen plenty of broken coolers on 3-500Zs and
none on 3-400Zs. . . More is not always better.
>Any thing else I need to know about that amp that will help either confirm
>or cause me to reconsider my decision?
>
? If it has an open frame resonant-choke, I would pot it in laminating
resin. Instructions are on my Web site. // If you have a modern
transceiver, you might want to add high speed switching to the amplifier.
($60) // Step-start would be nice. // Henry's glitch-R in the neg. HV
lead is a mistake. A glitch R should be added to the pos. HV circuit.
// It might be prudent to add 3A glitch protection diodes across the
(irreplaceable) meter movements.
- good luck, Marty
Rich...
R. L. Measures, 805-386-3734, AG6K, www.vcnet.com/measures
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