Simplistic MosFET HV Shunt Regs

[jeanlucdemarc]

Salas SSHV2-dimensions

For representation and for hole drilling.
136 x 48 mm
Output side : 4.25mm(in-- of 48mm) and 5.55mm(in-- of 136mm).
Input side: 14.45mm(in-- of 136mm) and 3.55mm(in .. of 48mm).
Hole 3.5mm

 

[Salas]

...Very nice

 

[soldersober]

What would you say is the longest wire length from the regulator to tubes? 1 meter run from a separate chassis OK?
Thanks!

 

[Salas]

If converted in two wire output mode OK but that will add some resistance to it. Keep the wiring kinda thick. If in its native Kelvin four wire mode it may gather noise on the sense lines in case its still stable by all that length's inductance and extended loop area. Needs a scope to know what happens when pushing chances.

 

[soldersober]

Thanks, good to be warned

 

[euro21]

1 meter run from a separate chassis OK?

I use 2m length umbilical (four wire HT - twisting F,F0 and S,S0 - shielded with copper screening).

 

[merlin el mago]

Salas I have a load of 150mA, it's possible to mod SSHV2 to support?

There are some much higher IDSS IXYS depletion mode parts to replace the DN2540s so to push the CCS limit high, like IXTP 08N50D2, but I don't know how stably they would react in practice. Dissipation and sinking would also change of course.

Salas changed Q1 DN2540 for IXTP01N100D max. CCS 150mA mine real load is 140mA but I need 20mA for the SSHV2 so can't reach te target of 160mA the power tx is 240V 120VA max. Vout is 173V and the target is 170V but there is a big hum. How can fix it?

The filaments are AC with center tap connected to signal ground, twisted touching the chassis. Before without the SSHV2 same AC filaments and no hum or noise.

 

[euro21]

IXTP01N100D max. CCS 150mA

Really?
IXTP01N100D is 100mA device.

 

[merlin el mago]

Yes Bela measured across T.P. R5 10R 1,5V.

Now after warm up CCS max. 1.095V = 109.5mA, max. B+ 132V

Cheers
Felipe

 

[Salas]

There is a 500V 800mA one too the IXTP08N50D2

 

[merlin el mago]

Wtih this one I will reach 160mA CCS? Again not available in Europe, only Mouser or Digi-Key.

 

[Salas]

Wtih this one I will reach 160mA CCS?

If you put two for both Q1 & Q2 positions yes or a Q1 like that and a DN2540 for Q2 that has >160mA IDSS

Again not available in Europe, only Mouser or Digi-Key.

Sum up a bunch of things you might need from one of those stockists over a period of time above a certain $$ amount that they grand the shipping cost and then ordering from the US makes sense.

 

[euro21]

Again not available in Europe, only Mouser or Digi-Key.

Felipe, mouser.es is in Barcelona.
Call them.

CUSTOMER SERVICE OFFICE

+34 93 6455263
espana@mouser.com
Parque de Negocios MAS BLAU I
Edificio Muntadas, Esc. B
C/ Solsones nº 2, Planta 2 Local C1 y C3
08820 El Prat de Llobregat
Barcelona
Spain


https://www.mouser.es/ProductDetail...aqLv1G%2bIPoGDbwEouHlQ4gHijoF5IkupEaqDvMjxg==

 

[merlin el mago]

Thanks Bela I know, it's only a sales representative office. If you don't buy a lot of money the shipping expenses are very high not like RS or Farnell.

 

[poty]

1. ...max. CCS 150mA mine real load is 140mA
2. but I need 20mA for the SSHV2 so can't reach te target of 160mA
3. the power tx is 240V 120VA max.
4. Vout is 173V and the target is 170V
5. but there is a big hum... Before without the SSHV2 same AC filaments and no hum or noise.

Wtih this one I will reach 160mA CCS?

Considering 1 and 4 in the first message there are two problems and reaching 160mA will solve only one (and possibly worsen the second).
For 4: what do you have before SSHV2 now? Something should be in between of your transformer in point 3 and the SSHV2 to "eat" the voltage!
For 2: 20mA - is the minimal current for SSHV2, you need probably some spare current for the job that powered device doing (I mean you should consider this, not only "spare current for SSHV2).
For 5: if you had not changed anything before adding SSHV2 you should do it now, because SSHV cannot work properly without the necessary spare current and voltage.

 

[merlin el mago]

I used CRCRC to drop the voltage between the rectifiers and the load.

 

[poty]

Then you should consider to use lower values for Rs in your filter. This will raise voltage and make it suitable for SSHV2.

 

[merlin el mago]

I know, the problem is reach a CCS of 160mA....

 

[poty]

Yes, but you should get a "baseline" (I mean the current will change with the voltage increasing, because 3V across the actually used schematic is very low).

 

[merlin el mago]

I'm sorry I don't follows. I tried without Rs only 3 capacitors in the PSU.