>
>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
mandatory.
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
have
>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
>available.
>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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