RF and AF probe for VTVM, TVM, VOM , DVM and Oscilloscopes

[Smithdoor]

Buildind probes for VTVM, TVM, VOM , DVM and Oscilloscopesbuilding probes.
I am building my own probes for my VTVM and Oscilloscope.
Hope popes the photos and schematics of there probes.

Dave

Latest probe quadruple for AF and RF work and RF for VOM uses

[Bazz4CQJ]

Hi Dave

this is a subject which has been discussed a lot on the forum over some years.

One subject of interest has been the really good results that certain companies have achieved with their probes (e.g. Boonton and Marconi) which amateurs have found hard (impossible?) to replicate.

The 1SS86 silicon schottky is a diode which may be worth a try.

B

[Smithdoor]

It is problem with almost all groups.
The only fix is sticky threads.

Here photo of my probes from a old wind-chime and drawing in pdf on how I did the probes.

Dave

Originally Posted by Bazz4CQJ

Hi Dave

this is a subject which has been discussed a lot on the forum over some years.

One subject of interest has been the really good results that certain companies have achieved with their probes (e.g. Boonton and Marconi) which amateurs have found hard (impossible?) to replicate.

The 1SS86 silicon schottky is a diode which may be worth a try.

B

[Cruisin Marine]

It is too late for me to think straight. Is the 4 diode version like a full wave voltage doubler?

[Smithdoor]

Here some history I found on internet on the Quadruple

Aka Quadruple
The Greinacher voltage doubler is a significant improvement over the Villard circuit for a small cost in additional components. The ripple is much reduced, nominally zero under open-circuit load conditions, but when current is being drawn depends on the resistance of the load and the value of the capacitors used. The circuit works by following a Villard cell stage with what is in essence a peak detector or envelope detector stage. The peak detector cell has the effect of removing most of the ripple while preserving the peak voltage at the output. The Greinacher circuit is also commonly known as the half-wave voltage doubler.[2]

Figure 3. Voltage quadrupler – two Greinacher cells of opposite polarities
This circuit was first invented by Heinrich Greinacher in 1913 (published 1914[p 2]) to provide the 200–300 V he needed for his newly invented ionometer, the 110 V AC supplied by the Zurich power stations of the time being insufficient.[3] He later extended this idea into a cascade of multipliers in 1920.[p 3][4][p 4] This cascade of Greinacher cells is often inaccurately referred to as a Villard cascade. It is also called a Cockcroft–Walton multiplier after the particle accelerator machine built by John Cockcroft and Ernest Walton, who independently discovered the circuit in 1932.[p 5][5] The concept in this topology can be extended to a voltage quadrupler circuit by using two Greinacher cells of opposite polarities driven from the same AC source. The output is taken across the two individual outputs. As with a bridge circuit, it is impossible to simultaneously ground the input and output of this circuit.[6]

Dave

Originally Posted by Cruisin Marine

It is too late for me to think straight. Is the 4 diode version like a full wave voltage doubler?

[Smithdoor]

Originally Posted by Cruisin Marine

It is too late for me to think straight. Is the 4 diode version like a full wave voltage doubler?

It dates back to 1910s

Dave

[Cruisin Marine]

It dates back to 1910s


At least I am a mere 110 years behind the times, that is good for me

[Bazz4CQJ]

I don't recall seeing a commercial probe using 4 diodes.
I think it is also the case the the really good instruments like the Boonton had closely matched probe/amplifier combinations.

B

[Smithdoor]

Originally Posted by Bazz4CQJ

I don't recall seeing a commercial probe using 4 diodes.
I think it is also the case the the really good instruments like the Boonton had closely matched probe/amplifier combinations.

B

I did not find any it was 1 or 2 diode.
But only found half wave too.
I was looking for full wave and only found shop made.

Dave

[Smithdoor]

Originally Posted by Bazz4CQJ

I don't recall seeing a commercial probe using 4 diodes.
I think it is also the case the the really good instruments like the Boonton had closely matched probe/amplifier combinations.

B

This may help to see how the the two diode expand to full wave.
If add a 4.7 resistor to schematic it is very common probe.
The Quadruple is just two Greinacher circuit for full wave probe.

The Greinacher circuit is 20hz to 50Mhz it even use tube version on older VTVMS

Dave

[Smithdoor]

This is from 1984 ALLR Book for probes.

This found in old VTVMS using one tube .
It maybe to keep cost by only using one tube this only a guess

Originally Posted by Bazz4CQJ

I don't recall seeing a commercial probe using 4 diodes.
I think it is also the case the the really good instruments like the Boonton had closely matched probe/amplifier combinations.

B

[Bazz4CQJ]

There's a good article on Boontons here http://ve2azx.net/technical/RF-Probes.pdf.

For some reason, that does not open in Chrome unless I go incognito.

B

[Cruisin Marine]

I will have a go at constructing the quadruple probe as soon as I can find a case to put it in. An old sharpie type pen or cigar tube will do.
I will compare it to my single diode design taken from an old Pye manual (probably Cambridge).

[Bazz4CQJ]

Originally Posted by Cruisin Marine

I will compare it to my single diode design taken from an old Pye manual (probably Cambridge).

The question that raises is what are the various criteria you will need to assess what's good?

B

[Cruisin Marine]

I will just test with a sig gen and measure level on an AVO 8 and compare levels and freq. response. Not an exhaustive test, more a comparison.

[Smithdoor]

The download is great Thank you
I will make a real drawing in next few days and post it here.

Dave

Originally Posted by Bazz4CQJ

There's a good article on Boontons here http://ve2azx.net/technical/RF-Probes.pdf.

For some reason, that does not open in Chrome unless I go incognito.

B

[Smithdoor]

Schematic of first

Originally Posted by Bazz4CQJ

The question that raises is what are the various criteria you will need to assess what's good?

B

[FrankB]

We are lucky these days with the solid state parts. My old Sylvania Polymeter used a loctal tube in the RF probe.
That quad probe looks quite interesting.
I wonder how 1N21 diodes would work in that config.?

[Smithdoor]

Originally Posted by FrankB

We are lucky these days with the solid state parts. My old Sylvania Polymeter used a loctal tube in the RF probe.
That quad probe looks quite interesting.
I wonder how 1N21 diodes would work in that config.?

It may work I am still looking for right diode.
The 1N34 goes to 250Mhz.
My probes are built in side a 12mm tube for good hand fit. Aka old wind-chime

Dave

[Smithdoor]

Data on Quadrupler probe
https://workforce.libretexts.org/Boo...rs%2C_and_More)


Dave