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[AMPS] What (modern) tube to use?

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Subject: [AMPS] What (modern) tube to use?
From: (Joe Subich, W8IK/4)
Date: Fri, 19 Feb 1999 10:54:30 -0500

> Joe's comment is not quite correct.  Henry has been using 3CX1200s in
> several of their HF amps for years.

Commented on the Henry designs elsewhere ...

> However, Joe's point should be kept in mind.  A tube without
> widespread commercial use might suddenly disappear from the market.  On
> the other hand, this didn't help the 4-400A...

The 4-400 is a rather special case.  It's primary niche was in 1 and 2.5 KW
AM broadcast transmitters.  With the cost to retube a transmitter pushing
$2 K (two modulators, two finals) every three ot six months in many stations
and the cost of good staff engineering, it became an economic decision for
stations to move to the solid state transmitters at replacement time.  Once
that happened, the market for the 4-400 dried up (hams only wanted the
pulls <G>) and the tube went away ... thus my concern for any tube without
a significantly broad commercial acceptance.

> Rich Measure's recent post about running a 8171 at 2.5 KV and 1.5 KW out
> is interesting too.  His comment about cooling at amateur power levels
> and the chassis space of a 4-1000 frames the question nicely.

The other concern here is the cost of the 8171 (> $1K new) and the air
socket ($350 - $500).  The cost can be improved by scrounging but I don't
know if the 8171 solution can be made competetive with a new 4CX1600 or
8877 pulls.  Of course, the 8171 is strictly a homebrew solution ... not
an option for the majority of hams.

> So what if you can heat your shack with the filament power (pun intended).

You may need the heat "up north" ... I want to cool my shack with the
amplifier <G>!
   ... Joe Subich, W8IK/4  ex-AD8I

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