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[AMPS] What (modern) tube to use?

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Subject: [AMPS] What (modern) tube to use?
From: (Rich Measures)
Date: Fri, 19 Feb 1999 13:48:46 -0800
>> 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.

?  8171s with ok emission and cosmetic probs. can be had for a few 
hundred dollars.  I paid $75 for a surplus sk300a  socket.  If one spent 
$600 for a tube and socket, the cost is $30 per kW pep when the tube is 
operated at max. capability.  The 8170 and the 8171 are the two most 
parasite-damage resistant tubes I know of.  There is no gold plating on 
the grid to sputter off during an intermittent vhf parasitic-osc.  The 
cathode design can resist virtually anything except being dropped on a 
concrete floor.  
>> 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>!

?   The good news is that the 8171 does not need to be left on because it 
is "instant on".  Thus, it makes no heat when laying in wait.    When I 
ran one, I found that I needed it only occasionally.  During the summer, 
I opened the window to let the heat escape.  During the Winter, I used it 
to take the chill off of the room in the mornings.  


R. L. Measures, 805-386-3734, AG6K,  

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