VVR installation

[Colas LeGrippa]

I have a VVR ready to install. One question: is the mica meant to isolate the transistor from the chassis ? Shall I use a heat sink , or the chassis becomes one when used with the mica ?

Thanx

Colas

[kagliostro]

The mica is to isolate the mosfet



you can use the chassis or a heat sink (it must be adequate in measures to the use)

here you have a large documentation on VVR

http://www.el34world.com/Forum/index.php?topic=6899.0

the short are the wires that connects the mosfet to the circuit, the best

Kagliostro

[Colas LeGrippa]

grazie mille, sei com' un' fratello per me!

[Willabe]

Steel chassis will not transfer the heat away from the mosfet well. Aluminium will work well as a heat sink. But the mosfet still needs to be mounted in a place on the chassis that is away from heat sources (power/rectifier tubes, PT) and has air flow so the chassis can dissipate the heat into the air.

A higher wattage amp on an aluminium chassis even with good air flow, might still need a heat sink.


           Brad              

[Colas LeGrippa]

it's no problem, the chassis is .125in  aluminum and the amp is 10W or so, thanks !

Colas

[Colas LeGrippa]

VVR installed on power tube only. Works great, I lowered the 6V6 plate down from 420V to 315V, and the tone is much better.( super champ modified).  I can swap to an EL34, 6L6.........and raise the B+ accordingly. Instead od buying the VVR kit as I did ( 3 years ago ), for my next build I'll use parts I have mostly, but the  regulator,  for much less than I paid then.
Regards

Colas

[kagliostro]

For VVR you may consider also cheaper mosfet than the NTE2973 - NTE2377

NTE2973 (14A 900V) € 16.46
http://www.nteinc.com/specs/2900to2999/pdf/nte2973.pdf

NTE2377 (8A 900v) € 31.94
http://www.nteinc.com/specs/2300to2399/pdf/nte2377.pdf

(price are from Farnell online shop)

-------------

IRFP460 (20A 500V) € 8.62
http://docs-europe.electrocomponents.com/webdocs/0791/0900766b8079122f.pdf

IRFPE50 (7.8A 800V) € 5.65
http://docs-europe.electrocomponents.com/webdocs/0791/0900766b8079124c.pdf

STW11NK100Z (8.3A 1000V) € 3.63 <== This seems a good choice
http://docs-europe.electrocomponents.com/webdocs/0db2/0900766b80db2783.pdf

(prices are from RS online shop)

hope this will help to contain costs

Ciao

Kagliostro

[Colas LeGrippa]

Buon giorno ! Thanks for the tip Kagli, I have an electronic ( chinese crap hey hey ) store not far from my place in Montreal where I still can find the mosfet for cheap.

Regards
Colas