Hi Lon,
Every consider using MOSFET's for this application?
These are available in 1000 & 1200 volt versions from IR, IXYS, & ST, in
TO-220 packages. The pinout would even be compatibile with the old 2N6740's.
73 & Good morning,
Marv WC6W
http://sql.net/wc6w/
--- On Wed, 1/19/11, kingwood <k5jv@kingwoodcable.com> wrote:
> From: kingwood <k5jv@kingwoodcable.com>
> Subject: [Amps] Suitable switching transistors found
> To: "Amp Reflector" <amps@contesting.com>
> Date: Wednesday, January 19, 2011, 4:22 PM
> Greetings to all,
>
> I have just finished evaluating
> two types of hi-voltage switching
> transistors to replace the original, inadequate, device in
> the factory
> Ameritron QSK-5 and QSK-5PC units.
>
> Originally I used 2SC5305
> transistors. These worked find for a
> reverse bias of 700 to 800 volts. Unfortunately, I
> have not been able to
> locate a current source for these devices. Thus the
> search for another
> replacement.
>
> The 2SC5589 is a suitable
> replacement, and will allow raising the
> reverse bias to well over 1,000 volts. However, this
> devise is quite large
> and is not so easy to adapt to the board.
>
> The BU508A is the transistor I
> have settled on. It has basically
> the save ratings at the 2SC5589, but is about 1/3
> smaller. It's lead
> spacing wider than that of the original transistor, but the
> leads,
> themselves, are the same as a standard T0-220. These
> leads are easily bent
> to fit into board and, due to its smaller size, it fits
> quite nicely.
>
> I strongly recommend that, if
> you have to replace the switching
> transistors in your QSK-5, for what ever reason, that you
> install standard
> T0-220 sockets to the board. These sockets are
> readily available and will
> really save wear and tear on the board.
>
> 73 de Lon, K5JV
>
> Lon W. Cottingham
>
> 1110 Golden Bear Ln.
> Kingwood, TX 77339
>
> 281-358-4207
> 281-795-1335 Cell
>
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>
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