Re: 60kV 50MHz HV Divider Completed

["Tesla list" <tesla-at-pupman-dot-com>]

Original poster: "by way of Terry Fritz <teslalist-at-qwest-dot-net>" <dhmccauley-at-spacecatlighting-dot-com>


Yes, the resistors are high voltage type resistors.  They are similar to the
THV type Caddock ultraprecision hv resistors but of an older vintage which
isn't being made anymore.
They are 50meg, 10kV resistors with a tolerance of 0.1%.  A 500kV divider
would be a challenge at the least,but you sound like you are well on your
way!

The Captain


 > Hi Captain,
 >
 > I guess "I" have to ask if the resistors are high voltage types too?  At
 > 10kV each I am sure they are ;-))  But "ordinary" resistors are pretty
 > voltage variable!  Here is some data for our 10Mohm 1/2W Yageo carbon film
 > resistors of MMC fame:
 >
 > Voltage (DC)    Current (mA)    Resistance (Mohm)       Power (mW)
 > 250             0.0248          10.0806                 6.2
 > 500             0.0502          9.9602                  25.1
 > 750             0.0759          9.8814                  56.9
 > 1000            0.1026          9.7466                  102.6
 > 1250            0.1303          9.5933                  162.9
 > 1500            0.1593          9.4162                  239.0
 > 1750            0.1899          9.2154                  332.3
 > 2000            0.2229          8.9726                  445.8
 > 2250            0.2579          8.7243                  580.3   Past power
 > rating
 > 2500            0.2959          8.4488                  739.8
 > 2750            0.3379          8.1385                  929.2   Thermal
drift
 > 3000            0.3989          7.5301                  1195.2  Thermal
drift
 > 3250            Thermal failure (core cracked)
 >
 > For the MMC, we don't really care if the resistance varies 10%, but for a
 > voltage divider, they would not work.  It is interesting how voltage
 > dependant the resistance is.  Not sure why...
 >
 > Your voltage divider is great!!!  Neat how you have compensated it!!.  If
 > you really want a challenge, try making one for 500kV at like 3pF loading
 > without disturbing the coil's fields ;-))  Be great of directly measuring
 > top voltage!  I have been trying for about 5 years :o))  A capacitive
 > voltage divider up the center is as close as I have thought of (Jennings
 > style).  Still messes a lot with the coil, but the effects are
predictable...
 >
 > Cheers,
 >
 >          Terry
 >
 >
 >
 >
 > At 10:24 AM 5/15/2003 -0400, you wrote:
 > > > Hi Dan,
 > > >
 > > > I couldn't tell from your schematic what type of caps were
 > > > used for the 82
 > > > pF compensation caps.  My assumption is that they are ceramic.
 > >
 > >Yes, that is correct.  Both Vishay and AVX makes these type of high
voltage
 >msnip...