Electronic Choke for Valve Amplifiers

[psaitz]

Hi!

Menno van der Veen - located in the Netherlands - offers an electronic choke. The description an technical data sounds great (in theory).

Has anyone tested/used this electronic choke in a valve power amplifier? Is it really better than a classic choke? I'm interested in the schematics too. Where can I get it?

Thanks for your help
Peter from Vienna/Austria

[TheGimp]

It looks like a gyrator.

Do a search on "Gyrator Plate Load" and you will find lots of discussion about it.

It will not store energy like a real choke. Otherwise it will work like one in a power supply for ripple rejection.

As a plate load it will not allow the full voltage swing of a true inductor plate load.

[Wavebourn]

Gyrator plate load and gyrator instead of a power filter choke are very different beasts. The first is a good improvement, the second is suboptimal. Beauty of PS filter choke is, it stores an energy. High impedance in frequency band of amplified signal is it's minus. If to use active devices to filter PS ripples, I would rather prefer such topologies that offer low output dynamic resistance, instead of imitation of choke weak points.

[LinuksGuru]

Personally I use 4H/400mA fixed air gap toroidal chokes. Quite small and efficient.
Additionally, I have built regulated stabilized power supply 500V/0.5A.
IMHO optimal solution is to use traditional CLC or stabilized regulated power supply, or even better, combination of both.

[Bigun]

Another thing to bear in mind, real chokes create magnetic fields around them (leakage flux) which can couple hum into your amplifier despite good B+ filtering.

Nevertheless, I like real chokes for their simplicity (ease of design, construction, debugging and maintenance) - I suspect they might be more reliable but I've no data to support that.

[ArtG]

Originally Posted by LinuksGuru

Personally I use 4H/400mA fixed air gap toroidal chokes. Quite small and efficient.
Additionally, I have built regulated stabilized power supply 500V/0.5A.
IMHO optimal solution is to use traditional CLC or stabilized regulated power supply, or even better, combination of both.

Can you suggest a source for a small quantity purchase of such an item?

[LinuksGuru]

Originally Posted by ArtG

Can you suggest a source for a small quantity purchase of such an item?

I have ordered bunch of them straight from the factory along with other items for our business, I did not found anything comparable in any large European electronic store.
If you are in Europe, I can sell them for 25 GBP/pc, but if you are outside Europe, shipping cost will be unreasonable high and prohibitive (choke weights 1.8 kg).

[rsumperl]

Originally Posted by LinuksGuru

Personally I use 4H/400mA fixed air gap toroidal chokes. Quite small and efficient.
Additionally, I have built regulated stabilized power supply 500V/0.5A.
IMHO optimal solution is to use traditional CLC or stabilized regulated power supply, or even better, combination of both.

Can you post a schematic of your 500v supply?

Thanks
Ray

[DF96]

I am intrigued by Fig 4 in the link from post #1. It shows the decay with a 10H filter choke in the PSU, between two 330uF caps. There are two prominent components which shift up in frequency by a factor of about 3! I would have expected LC ringing to be rather more stable in frequency. Of course, we don't know exactly what the initial stimulus was, and whether DC through the choke is changing its inductance.

Any ideas?

[LinuksGuru]

Originally Posted by rsumperl

Can you post a schematic of your 500v supply?
Ray

I'll do it when finish everything. Right now I have working stabilizer built on the teflon board very rough way. The next things to do are turn on delay (40 - 60 sec to avoid cathode poisoning), and PCB. I do not wish to post schematic for device which is not tested enough.