[ARC5] BC-453 mods

[J. Forster]

Yes. Or a Darlington-White. I think it needs a resistor or two.

-John

===============


> That makes sense.  The JFET would be the input device and the bipolar is
> probably a cascode connection (kinda like a grounded grid amp) to stand
> off
> the higher voltages.
>
> Dennis AE6C
>
> On Sat, Aug 6, 2011 at 1:15 PM, J. Forster <jfor at quikus.com> wrote:
>
>> I've seen two transistor versions, a FET and regular transistor, coupled
>> together, used.
>>
>> -John
>>
>> ================
>>
>>
>> > FYI.  A JFET is not a triode  It does have a "triode" like region
>> prior
>> to
>> > pinchoff, but beyond that Vds bias point the current saturates like a
>> > pentode.  The pinchoff voltage is low enough that it is rather
>> impractical
>> > ficult to run it as a triode in most cases.  But it's a good sub for a
>> > pentode and you don't need any "screen" voltage.  The biggest
>> limitation
>> > is
>> > the max operating voltage.
>> >
>> > Dennis AE6C
>> >
>> > On Sat, Aug 6, 2011 at 9:50 AM, Kenneth G. Gordon
>> > <kgordon2006 at frontier.com>wrote:
>> >
>> >> Making the 1st IF regenerative in any of the models is easily done,
>> >> and makes a big difference for weak signals....not so much for strong
>> >> ones.
>> >>
>> >> Two pieces of #12 TH or THHN (with insulation still on) soldered to
>> >> the grid and plate terminals, and a pot in the cathode is all it
>> >> takes.
>> >>
>> >> The main problem I always had when trying to replace tubes with FETs
>> >> is that an FET is basically a triode. For multi-grid tubes, this is
>> >> often a real problem.
>> >>
>> >> For triodes, not so much.
>> >>
>> >> I have a pair of Tubesters here which I took out of a Heathkit VTVM.
>> >> As I remember it, one replaced a 6AL5 and the other a 12AX7.
>> >>
>> >> vy 73,
>> >>
>> >> Ken W7EKB
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>>
>