[AMPS] Reflector thoughts about my future amp project wanted!

2 2@vc.net
Tue, 11 Dec 2001 05:35:28 -0800

>Hello Gang,
>    Went to the swap meet last weekend in Mesa AZ. and came home with a pair
>of medical pull 4PR-1000 tubes in what appear to be like new condition. (One
>is an EIMAC and the other a Triton and both have early 98 date codes.)  I
>was told they were pulled due to the time in service, not performance so I
>am hopeful.  The price was right even if only one is working.  If both are
>NG then I have a nice pair of bookends or lamp basses.  ;>} I'll remain
>optimistic for the moment.
>    First order of business is to find someone who can put them on the air
>and check them out or a commercial tester who can test them to see what
>condition their condition is in.  (OPPS, flashback to '60 rock.)   ;>} If
>anyone has info either
>option, let me know.
>    Second item is sockets and chimneys.  Two would be nice but one of each
>will do for a start.  

//  The elegantly too-simple split-chassis cooling method employed in the 
Heath SB-220 offers superior cooling with less noise that the Eimac 
"air-system" socket/chimney, which requires a high-pressure (not quiet) 
blower.  However, if you are building this amplifier to impress the 
unenlightened, air-system cooling and a viewing window is almost 

Making the 4-1000A/8166 easier to drive requires high anode potential,  
8166-builder      Terry, W6RU told me that 7kV is FB for SSB.  I have a 
friend who runs 8kV to a pair of 8166s in g-g.  However, a single 8171 
would deliver 3x as much steam, take up half the chassis space, and could 
be driven with 150w instead of 320w.  

>Let me know what you have and what you want/need for
>them.  A trade is ok by me as I do have a collection of stuff myself.
>    Third item is knowledge.  Once again the collective wisdom of the group
>is requested as I really don't like reinventing the wheel and for some of
>you this is old hat.  Here is what I am curious about...
>1.    I remember from comments on this reflector that the 4-1000 takes a bit
>of drive to get full output and it likes lots of HV.  Something like over
>130 watts of drive is not unusual especially when you get to 10M. 

//   Since the 8166 screen is resonant just below 10m,  operation there 
is reportedly problematic.  

> As I recall 4KV is preferred to say 3KV and I see from the one spec sheet I 
>that it can use up to 5.5KV under 30Mhz.  I am thinking that 4KV is probably
>a good place to start as it is doable with what I have on hand.  I question
>all this because I will most likely have only 100 watts or less drive
>2.    IF in GG service they are tough to drive to max legal smoke with 100W,
>then how about Grid Driving it and running AB2?  Looks like it only needs
>something like 14 watts to get full tilt boogie out of the bottle that way

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