DIY scintillation probe: the easy way

This guide is under continuative update. 
updated 9 June 2019
updated 12 June 2019
updated 21 June 2019


Many backers of my USB PMT adapter project on Kickstarter asked me to write a simple guide that explains how to make a scintillation probe to be used with the USB PMT adapter for gamma spectroscopy. This guide is focused on the “dirty cheap” way to construct one at home without special tools.

I know two ways of making a probe:

  • Alluminium turned enclosure with internal teflon spacers. Internal mu-metal shielding and internal voltage divider.
  • Black tape and scissors “dirty cheap” probe.

The first type of probe is rugged, reliable and hard to make at home if you don’t have access to a lathe, a mill and have the skills needed to precise machining alluminium and plastics. This type of construction will be discussed in a new guide that I’ll write in few weeks. The second type that is treated here is easy, quick to make. It could be easily improved adding a proper aluminium enclosure.

How is made a scintillation probe and what I need to make one?


Example drawing of a scintillation probe


Scintillation probe with a well-type scintillation crystal


A typical scintillation probe consists of a light tight enclosure with, inside of it, a photomultiplier tube (PMT) that is coupled to a scintillation crystal. The voltage divider needed to feed the tube and extract pulses usually is placed on the back of the PMT tube. The tube could have wires soldered directly to the voltage divider PCB or some kind of socket. In this case the divider is connected to the socket that is connected to the PMT.

To make one you need:

On the right I’ve added a direct link to my favourite suppliers.

  • A scintillation crystal OST Photonics and Epic Scintillator
  • Some silicon optical coupling grease The Rad Lab
  • A photomultiplier tube The Rad Lab
  • A voltage divider for the PMT and it’s socket (if it needs one) The Rad Lab
  • A light tight enclosure that puts all pieces together. In this case… just some well tight black electrical tape.

PMT tubes example

The following pictures shows a typical photomultiplier tube usable for gamma-ray spectroscopy. I strongly recomand you you to buy tubes from a reliable source. My favourite tubes are from Hamamatsu and specifically the R6095

R6095 PMT from iRad – The rad lab
R6095 with it’s socket
Front optical window

Scintillation crystals

There are many type of scintillation crystals avaiable. The most common are:

  • LYSO    usable but have internal Lu176 gamma emission
  • NaI(Tl)    this is the type of crystal to buy
  • CsI / CsI(Tl) / CsI(Na)    low FWHM compared to NaI(Ti) hard to find
  • BGO    low FWHM compared to NaI(Tl) harder to find

For gamma-ray spectroscopy the preferable type is NaI(Tl). They can be found on eBay from cheap from ex CCCP countries.

The quality of your spectrometer expressed by the FWHM capacity of the system crystal-PMT-amplifier-ADC must be in the range of 8% or below. Small value of FWHM indicates better resolution capability of the spectrometer. Usually surplus soviet crystals have a variable FWHM because of they age and storing condition in the range 8-12%. A good crystal must be colorless with ultra -brite white internal walls. If not maybe they could be yellowish or stained and this means that they are trash.

Russians NaI(Tl) crystals. Usualy they are enclosed in a round machined steel enclosure.
On the left a CsI undoped crystal. On the right four LYSO crystals. They could be used but I prefer to use the LYSO as radioactive calibration source because it’s internal Lu176 gamma emission or for display in my collection :3
Bicron plastic scintillators. Because they low Z they are useless for gamma spectroscopy

Copling between the crystal and the PMT tube

The optical face of the PMT tube is where the scintillation crystal will be coupled. For this parpuse use some specific silicon optical coupling grease. It is very cheap and you’ll need a very modest quantity.

An important thing to note is the size of crystal and PMT. You must use a PMT with an optical windows bigger than the crystal. If you cannot you’ll lose some resolution. For example if the crystal is 43mm diameter and PMT optical window is 38mm you can couple they and expect some little resolution loss. If you try to couple to a 24mm PMT this coupling doesn’t work well and must be avoided.

A perfect coupling. PMT is 30mm diameter and crystal is 28mm internal diameter. It will works just great!
Another good coupling. A 10mm crystal on the optical window of a 30mm PMT
This coupling is BAD! A 30mm PMT on a 43mm crystal
An acceptable coupling. A 38mm PMT on a 43mm crystal. Is not a good coupling,I expect some 1% FWHM loss but it will work

Assemply the probe

So, you’ve find all the needed parts to assemble a probe? Good! Lets build it.

First, clean your desk, clean your PMT’s optical window and your crystal’s optical window too. You must remove all kind of grease from it like fingerprints with some alcohol. Put the crystal face up and spread over it’s optical end some silicon optical grease. Put the PMT otical window in contact to the crystal and spread the grease with little circular movements, this will remove bubbles of air. Don’t apply any pressure. The grease will make an optical coupling film between the crystal and the PMT. Now with some piece of black tape fix the PMT in position over the crystal.

Now countinue to wrap the black tape around the tube. No light must enter. Take care to tight the tape and to tight the coupling between the PMT and the crystal. I’ve closed the end of my tube with some black silicon glue. If your tube needs a socket you’ll need to enclose the complete assembly into a light tight enclosure. This because you cannot put black silicon glue under the socket.

Now, if you have some adesive mu-metal shielding sheet, you can cut it and wrap aroun your probe to add magnetic shielding to the tube. This is a good thing to do but, the tube will work also without it so, don’t worry about it at the moment, you can always add it! Connect your voltage divider circuit and your coax cable. Your probe is ready to be tested. My USB PMT adapter supply positive voltage from the central point of a BNC connector. I suggest to use a short (<=1mt) RG59 coaxial cable to connect the probe with the board. One end of the cable must have a BNC male connector, the other end, screen shield of the cable goest to the voltage divider – “minus” ground/cathode, the inner insulated conductor of the coaxial cable, feeds the voltage divider with high voltage. It goes to the + “plus” anode. If you use a mu-metal shield, connect it to – “minus”.

Notes about voltage divider

Photomultiplier dynodes need specific voltages and voltage ratio between each other. The voltage divider is specific for each photomultiplier. This guide explains how voltage divider is calculated. The Rad Lab sells PMT’s with voltage divider kit and instructions to build it. I strongly suggest to buy it from him and follow the assembly instruction. Here you can see the instructions provided for the R6095 and R9420


LYSO + ZnS(Ag) new order

Today I’ve made a new order from The Rad Lab. This time I’ve found on it’s ebay store a stock of 20 LYSO crystals to be used as gamma scintillators with my new SiPM photomultiplier. I haven’t wrote anything about it? Ok… I’ve bought from Mouser this AFBR-S4N44C013 Broadcomm SiPM silicon photomultiplier tube and it needs some little scintillator crystal.

Broadcomm 4x4mm SiPM

I’m planning to test it with LYSO from The Rad Lab. If it works well I’ll made a kickstarter campaign for an ultra small gamma

LYSO crystals under UV light

spectrometer based appon LYSO + SiPM with USB connection.

There’s no high voltage need by the SiPM! This means that I could design a very compact circuit. I’ve also bough an ZnS(Ag) scintillator disc to test my PMT and the new SiPM with it to try some alpha particle counting.

ZnS(Ag) image by The Rad Lab

Antenna rotor clean up

Some months ago I’ve received from the local A.R.I. radio club an old antenna rotor. I think it is a Daiwa but there is no label on it. It looks like a Kenpro KR400 too… boh? It was used for many years on the roof of a local OM. It was covered with grease, dirt and many other “bleah” things.

First thing to do, I’ve cleaned it with turpetine. This powerful spirit clean up grease with ease and it smells really good to!

Second thing, open it and check it’s gears. To open it, simple uncrew the four screw on the bottom. It’s gear set is ok, no broken teeths, just a lot of dirty of old dark gray grease. I’ve carefully separed the aluminium ring that was screwed with the top alauminium enclosure.

It makes with the inner-bottom alluminium motor/gearset assembly, a bearing. Now, there are a lot of stell ball aroud.

Dirty oil

I’ve collected the bearing’s balls, cleaned and left apart for future re-assembly. Separing the inner-bottom assembly from the top alluminium enclosure revealed that there is another bearing there. More steel balls to be cleaned…

Steel balls and half ball bearing

Third thing, clean with soap the rotor spliced in: top alluminium enclosure, inner-bottom assembly and bottom alluminium ring.

Fourth thing, paint this three pieces with a strong synthetic paint, re assembly everything applying some grease on the ball bearing tracks.

How the bottom bearing is made.
Zoom on the bearing’s track


I’ve used Anderol L786 grease


Mosley TA-33-JRN

I’m an ham radio operator since year 2008. I’ve started this hobby with simple and relatively cheap equipment: an FT757GX transceiver and a long wire with tuner. During this 11 years of activity mainly focused on HF bands, I’ve tryied to improve my radio station. At first I’ve changed the radio with a IC7000 then an FTDX2000 now I’m using an FDM-DUO SDR QRP transceiver and an FT897.

I’ve quickly realized that changing the radio changes absolutely nothing except it’s intrinsic ergonomicity. The key component of a radio station is the antenna! The first vertical antenna was an 12AVQ, a compromise that worked for many years. The first full sized dipole for the 20mt band, erected at 10mt from ground with 10 mt of free space around, was absolutely the best antenna I ever had! It was silent compared to the noisy long wire or the vertical antenna. Now I’ve changed my QTH from Fano to Gradara, a castle on a 62mt eight hill. Not bad considering that in Fano my old QTH was at sea level with hills around it.

With such a nice location what to put on the roof? A yagi beam antenna for sure! I’ve choosed the Mosley TA33JRN because it have a nice declared gain and it’s size and weight are within my cababilities of a single man putting it on the roof.

First, I’ve bolted two iron supports on the side of the center wall of my roof. This two supports are heavy, very well made. They are the type used from professional antenna installators. They can fix a 60mm diameter pole, they are bolted to the concrete with two wall fixing bolts 14mm diameter, 200mm long and they are separed from one to another with 1mt vertical spacing in order to improve weight load distribution on the concrete wall.

I’ve decided to make a 3 section telescoping pipe. The idea is to assemble the antenna atop the roof with the pole fully retracted then elongate it to the desired height. The first section is a 2mt long 60mm diameter extruded steel pipe with 5mm wall thickness. The second section is 50mm diameter extruded steel pipe with 4mm wall thickness and the last 2mt section is 42mm in diameter and 4mm in wall thickness.

I’ve insert each tube in the other for a 250mm lenght thenfor every insertion I’ve made three 10mm holes. Two, with a bolt soldered, is for quick blocking the pole. The second is for insert a long 8mm screw that block the section in position.

The complete, crude steel pipe, needs some kind of rust protection. I’ve painted it with zinc spry. It is sufficent to prevent corrosion.

Atop the last section, the one wich support the rotor, I’ve soldered four steel rings for guying.

For the rotor I’ve choosed an Yaesu G450. I’m not using a rotor cage because it’s datasheet say that my 0.49m2 antenna is well within it’s load capabilities. This rotor is very well made and doesn’t cost much… about 300€ The last 50 cm pole on the top of the rotor is an alluminium pipe of 50mm diameter and 6mm wall thickness. It supports the yagi antenna.

Last but not the last, I’ve used 4mm size Dyneema rope for guying the pole. This rope is specifically made for yatchs, it’s stronger than steel rope and is insensible to UV light, water and salt from the sea droplets. By the way I’m 1.5km far fom the Adriatic sea… I can see it from my roof.

Take a look at this video, it explains why Dyneema is better than steel cable.

Assembling the Mosley atop the roof procedeed flawless. I’ve assembled the boom first and secured it to the pole. Then, I’ve assembled and secured central dipole, reflector and director elements. They are long at maximum 8.5mt and they weight is within a kilogram… maybe a kilogram and half. Is easy to work with such light elements. I’m working in a telecom company here in Italy that is servicing telephone land lines. For me is a joke climb up a 12mt wood pole and change long (heavy) cables atop of it. If you are not so practic with working on elevated, dangerous places with big pipes/wires/exc… I suggest you to ask for the help of one or two persons. Security first!

One negative note about this antenna is the supplied assembly manual. It’s a joke! It’s completly useless. No complete assembly drawing, parts are listed but the bags that contains parts are not labelled… you must use your own imagination! This is not good! I’ve searched on the net and found some more complete (old) manual from Mosley. Looking at a complete drawing of the antenna helped me a lot.

Mosley_MP-33N_user          TA-33-JR_assembly_instructions        ta33jr

I’ve found this three files that helped me.

High voltage generation from 3.3-5V

This post describes my standard DC-DC HV converter

You know, to power up geiger tubes or photomultipliers there the need of high voltage at very low current drain. How to generate 400, 1000 or more volts from a single 5V supply or better 3,3V? Simple, let’s build a boost converter (Wikipedia). In this post I’ll describe my standard building block, the PWM drived, voltage multiplied boost converter. I’ve used it in many circuits, as notable example please take a look at my HV converter project page.

How does it works? Let’s look at the following picture. In my implementation the active element of the circuit, a N-type mosfet called BSP300, is capable to handle 800V and it only needs a proper PWM waveform generated by an MCU like Atmega328 from an Arduino or STM32F103 or other MCU’s to work.

My boost converter circuit

Briefly speaking, the input supply (5V) “charges” the magnetic field around the inductor L1 when the mosfet Q4 is energized by a positive PWM waveform (5V). The PWM signal is applied on the BSP300 gate. When the PWM signal reach the low state (0V) of it’s duty cycle, the mosfet disrupt the circuit causing the generation of an overvoltage across the inductor leads. Please visit Wikipedia for more info on PWM.

Duty cycle example

This overvoltage is caused by the magnetic field collapsing aroun the inductor. The overvoltage is rectified by a Shottky diode or, in my case by a voltage multiplier network. This voltage multiplier network is formed by D1/D2/D3/D4 and C2/C3/C4 and multiply input voltage by a factor of 4. The voltage multiplier network is a standard Cockcroft-Walton design.

Voltage multiplier basic circuit

At the output of the diode or the network usually you’ll add a capacitor to filter out the voltage ripple and then you have your high voltage ready to be used. The V_ADC output goes to an ADC input of the choosed MCU and makes possible to the MCU to know the output voltage then regulate it varying the PWM waveform duty cycle. The series of R1-R2-R3-R4 forms a 40Mohm resistor. With R5 that is 100kohm, this series of resistors is a voltage divider network. The voltage across R5 is 400 times smaller than the voltage across the complete resistor series. Mathematically Vr5=[Vin/(R1+R2+R3+R4)]*R5 so with 1600Vin you’ll get aprox. 4V. If your MCU runs from 5V and your ADC’s reference voltage is 5V you’ll stay in it’s input range. If you’ll use different reference voltage you’ll need to change the voltage divider ratio.

I’ve found this boost converter components calculator from Adafruit but I’ve found more usefull to use a standard MC34053 calculator and use it’s output inductor value as reference.

Adafruit calculator

How to generate the PWM signal? Take a look at this little “Arduino” code. It’s self explaining and it’s easy to be ported to whatever MCU and language you use.

Some notes about components selection

  • L1 must be a 3.3mH ferrite core inductor with the lowest internal resistance avaiable. It’s value is experimental, I’ve found that my circuit works best with this value. The inductor used is this ELC-11D332F
  • Diodes must be Shottky and rated minimum for 400V reverse voltage. Low leakage current fast recovery type are a must! Suggested model: BYG21M-E3/TR
  • Capacitors of the voltage multiplier must be rated minimum for 400V and they value is 4.7nF.
  • The BSP300 couldn’t be substituted. That mosfet is specifically designed to be drived by a PWM waveform from a MCU and it’s high voltage capability it’s essential. It’s also cheap and easy to found.

Some notes about my Arduino code

  • In this code I’m using A7 ADC pin to sample the generated voltage.
  • Pin 9 is PWM output to the BSP300 gate
  • A2-3-4-5 pins have internal pull up resistor enabled. This four pins are connected to a dip switch to select desired output voltage. The dip switch shorts to ground the selected line, the MCU read it as input.
  • The software calculate the desired output voltage via a simple function “read_jumper()”.
  • I’m also using a custom function called analogWrite16() because this function makes a 3Khz PWM output. The standard Arduino’s analogWrite() barely reach 900Hz frequency.
  • The frequency is very important because changing frequency you’ll need to change the value of the L1 inductor and also the capacitors of the voltage multiplier.
  • The circuit is designed to work at 3Khz.
//MadExp PMT adapter firmware v0.1
//Copyright 2018(C) Papadopol Lucian Ioan
//This program is free software; you can redistribute it and/or
//modify it under the terms of the GNU General Public License
//as published by the Free Software Foundation; either version 2
//of the License, or (at your option) any later version.

//This program is distributed in the hope that it will be useful,
//but WITHOUT ANY WARRANTY; without even the implied warranty of
//GNU General Public License for more details.

//You should have received a copy of the GNU General Public License
//along with this program; if not, write to the Free Software
//Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.

//Define some pins
const int analogInPin = A7; // Analog input pin

//Voltage conversion constant
const float conversionFactor = 0.00488;

//Global variable
int Output;

//Startup setup code
void setup() {

//Jumper pullups
pinMode(A2, INPUT_PULLUP);
pinMode(A3, INPUT_PULLUP);
pinMode(A4, INPUT_PULLUP);
pinMode(A5, INPUT_PULLUP);

//Main LOOP
void loop() {

//Reading voltage set point and reading actual converter output voltage
int Setpoint = read_jumper();
int sensorValue = analogRead(analogInPin);
int Input = sensorValue * conversionFactor * 400;

//Some calculation for PWM correction (more voltage? less PWM exc...)
int k = 0 ; //Costante di correzione

if (Input < Setpoint) {
k = (Setpoint - Input) / Input;
Output = Output + 2 + k;
if (Input > Setpoint) {
k = (Input - Setpoint) / 10;
Output = Output - 2 - k;
analogWrite16(9, Output);

int setpoint_minus_delta = Setpoint - 20;
int setpoint_plus_delta = Setpoint + 20;
if (Input <= setpoint_plus_delta && Input >= setpoint_minus_delta) {
if (Input > setpoint_plus_delta || Input < setpoint_minus_delta) {


//PWM @ 16bit resolution! From 0 a 4095 not 0-255 like stupid arduino library!!!
/* Configure digital pins 9 and 10 as 16-bit PWM outputs. */
void setupPWM16() {
DDRB |= _BV(PB1) | _BV(PB2); /* set pins as outputs */
TCCR1A = _BV(COM1A1) | _BV(COM1B1) /* non-inverting PWM */
| _BV(WGM11); /* mode 14: fast PWM, TOP=ICR1 */
TCCR1B = _BV(WGM13) | _BV(WGM12)
| _BV(CS10); /* no prescaling */
ICR1 = 0x0fff; /* TOP counter value 4095 12bit */
/* Comments about the setup
Changing ICR1 will effect the amount of bits of resolution.
ICR1 = 0xffff; (65535) 16-bit resolution
ICR1 = 0x7FFF; (32767) 15-bit resolution
ICR1 = 0x3FFF; (16383) 14-bit resolution etc....

Changing the prescaler will effect the frequency of the PWM signal.
Frequency[Hz}=CPU/(ICR1+1) where in this case CPU=16 MHz
16-bit PWM will be>>> 16000000/(65535+1)=244,14Hz
a 12 bit fa 16Mhz/(4095+1)= 3.9Khz
/* 16-bit version of analogWrite(). Works only on pins 9 and 10. */

void analogWrite16(uint8_t pin, uint16_t val)
switch (pin) {
case 9: OCR1A = val; break;
case 10: OCR1B = val; break;

//Read jumper function
int read_jumper() {
int point;
int jumper_presel = 0;
int jumper_state1 = digitalRead(A2);
int jumper_state2 = digitalRead(A3);
int jumper_state3 = digitalRead(A4);
int jumper_state4 = digitalRead(A5);

if (jumper_state1 == 0) {
jumper_presel = jumper_presel + 8;
if (jumper_state2 == 0) {
jumper_presel = jumper_presel + 4;
if (jumper_state3 == 0) {
jumper_presel = jumper_presel + 2;
if (jumper_state4 == 0) {
jumper_presel = jumper_presel + 1;

point = (jumper_presel * 50) + 500;
return point;

PRC320 power supply repair

My military HF manpack radio PRC320, 3 months after I’ve bought it, started to make a whistle and was not able to tune on any frequency. After few minutes it went KO. No audio at all. Damn! How to fix it? Let’s take a look inside!

Opening the radio is an easy task:

  • Disconect battery, antena connector and headset cables
  • Unscrew all the allen screws
  • Take apart gently, front and back pannels. They slide out the aluminium enclosure.

This is what I seen inside it

Inside PRC320

The Unit n° 5 is the first suspect. This module is the power supply. As a general rule in electronics servicing, check the power supply first! Let’s open it to verify if it’s doing it’s job.

Now, with extreme care I’ve reconnected front and back pannel and powered the radio via its external power supply cable. After measuring the voltages on 6 and 112V points my suspects where confirmed. No way to have some power supply, there’s no output voltage. I’ve removed the module from the radio to troubleshoot it.

Repair that module is not an easy task because it’s semiconductors are all obsolete and hard to find parts. Still at the moment I don’t have a suitable replacement for TR1: the main 24V to 12V stabilizer, that fried. I’ve found also the BC107 on the step up section KO. Giving a chance to a BD139 in place of TR1 resulted in a semi funcional radio: I could listen to radio stations but i couldn’t transmit! Ok, let’s search for a complete new module! This is not a trivial task: this modules are very hard to find, I’ve found one new, serviced from a guy that does this job, radio servicing, during his military career, on ebay for 80€! It’s not cheap.

Now with this new module in place the radio comes to life again in RX and TX! Nice… but I have still to deal with the old broken module. I’ll update this post when I’ll fix it. At the moment this file could help you, Module 5 schematics


This is the latest Free Version of Ham Radio Deluxe 5.0.2893 compiled by Simon Brown. Download here HRD_5.0.2893

Here you can download BecquerelMonitor 2011 MCA audio BecquerelMonitor-1.0

This is the patched version of BecquerelMonitor by Stanislav Prytuliak BecqMoni_patched password:

This is my AmericiuMCA (pre beta-release) software compatible with Maxim’s high speed spectrometers via SHproto v2 AmericiuMCA_build

MProg 3.5 for FT232 eeprom configuration mprog3.5

Borland Turbo C 2.01 original (3 floppy) tc201

Borland Turbo Pascal original 3.02 tp302

Mini60 HF antenna analyzer Windows software AntAN.exe

MadExp HV 5V to 900V step up converter firmware/arduino project (Arduino 1.8.3) with libraries. READ THIS FIRST! firmware_upload.pdf


Autunite specimen from China

Recently I’ve bought a little specimen of Autunite from China. My sample is 20mm in lenght, 15mm width and 6mm thick with nice green lamellar crystals. I’ve bought it from a chinese seller because I couldn’t find an equally nice sample from Europe.

Autunite specimen

I’ve received it after 30 days from the order and immediately I’ve painted it with transparent acrylic pain to avoid contamination with tiny powder that could be lost during handling.

I’ve tested it with my SV500 geiger counter that measure beta+gamma at contact in the range of 20-25mRad/h and 3-5mRad/h of gamma’s only. This is an highly active sample as expected. It’s radiation emission doesn’t travel too far in air and at just 10cm from the sample, just my scintillation probe could measure it. I’ve made a gamma spectrum of it’s emission with a NaI(Ti) scintillator.

Autunite gamma spectrum

As you can see it’s easy to detect it’s thorium and radium content. There are also decay products like Pb214. Bi214 is a characteristic decay product of Ra226. Take a look at the Ra226 decay chart below

Ra226 decay chart

In conclusion this specimen is not a fake made in China, is just a nice high activity sample.

NER10 X-Ray generator

I’ve bough from eBay a NER10 X-Ray generator tube. It was build in 1925-1930 I don’t know exactly when. It’s interesting to see how well made it is also, It’s massive and big in size and weight.

NER10 x-ray generation tube

I’ve no datasheet of this tube. Everything I know about this tube, I learned on this video

Der Floureszenzschirm befindet sich hinter dem Pappschirm.
Das Bild wird von dem quadratischen Spiegel (mit rotem Rand) wiedergegeben.
Diese Anordnung hat den Vorteil,daß die Kamera auf der nicht ganz so strahlenverseuchten Seite der Röhre stehen kann.
Die Röhre ist eine Phönix Radion Ner10,etwa 1925-1930 hergestellt.
Der Anodenstrom beträgt im Video etwa 3mA (bis 7mA sind möglich,allerdings geht dann die Spannung in die Knie) bei einer Spannung von etwa 50kV.
Der Heizstrom harmoniert am besten mit dem Hochspannungsteil (Röhrenwiderstand) bei etwa 2,8A.
Die Anodenspannung wird mit einem AC-Zeilentrafo,welcher von einer ZVS-Schaltung getrieben wird,und einer nachgeschalteten Kaskade erzeugt.
Die Kaskade ist in einem PVC-Rohr mit Ölfüllung untergebracht.Die Dioden der Kaskade vertragen einen Strom von 10mA@20kV;
die Kondensatoren haben eine Kapazität von 1nF und eine Spannungsfestigkeit von 15kV. 
Das ganze Teil sollte in einem Steampunk-Bakelit-Holz-1930er Jahre-Design rüberkommen.
Darum habe ich bewust diese alten Drehschalter verwendet.
Das obere Amperemeter zeigt den Röhrenstrom in mA an,das untere den Heizstrom in A

I don’t speek german but I think Google traducer made a good job:

The fluorescent screen is located behind the cardboard umbrella.
The image is reproduced by the square mirror (with red border). 
This arrangement has the advantage that the camera can stand on the not so sun-contaminated side of the tube.
The tube is a Phoenix Radion Ner10, made about 1925-1930.
The anode current in the video is about 3mA (up to 7mA are possible, but then the voltage goes to the knee) at a voltage of about 50kV.
--> IT NEED 50kV Nice!!!
The heating current harmonizes best with the high voltage part (tube resistance) at about 2.8A.
The anode voltage is generated with an AC line transformer driven by a ZVS circuit and a downstream cascade.
The cascade is housed in a PVC pipe with oil filling. The diodes of the cascade tolerate a current of 10mA @ 20kV;
the capacitors have a capacity of 1nF and a dielectric strength of 15kV.
The whole piece was supposed to come in a steampunk bakelite wood 1930s design.
That's why I've deliberately used these old rotary switches.
The upper ammeter indicates the tube current in mA, the lower the heating current in A.

This is the Anode, the corroded point is where electrons hits the metal and generates xray’s

The copper anode and the hole

The copper anode and the hole where the filament heats up.

Let we see the marks on the tube


The cathode socket with two wires soldered by me

Cathode socket

Anode is made of turned steel or maybe copper plated steel?

PRT-E750W & PRT-E1500W vfd settings

How to set correctly the PRT-E750W and PRT-E1500W  (are equals except for the power capability) VFD supplied with CNC 3020 and CNC 6040 chinese routers. Click to download: PRT-E1500W vfd settings

This is the CNC 6040 Setup for Mach3 by David Parish.

I’ve found that the two files are missing an important note. After factory reset the VFD with D001 to 1 and D176 to 1, will appare the word “Load” into the display. The reset is complete in few seconds. Now to continue the setup procedure you must set D001 to 1 again. D001 tells the controller that settings modify is enable. Without doing this you cannot modify any other setting.

This is the VFD controller.

This video shows how to change one of the setting of the controller, specifically one of the spindle settings that make it accept 400Hz PWM power drive.