Dear Angelo,
Plate chokes are the one place that there
is absolutely no fixed information to follow.
There are several factors when building amplifiers
and winding your own chokes:
The choke wire gauge needs to handle the full
D.C. amperage that the tube(s) will draw, plus,
the RF amperage that will be bypassed to ground in the
RFC bypass capacitor. Oftentimes, most amateur
amplifiers will only draw one to three amperes, so
20 - 26AWG silicon covered magnet wire suffices.
The choke needs to not be resonant anywhere the amplifier
will be transmitting (frequency-wise). This is called a
series-resonance, and its effects are fire and smoke. Just
using a heavier guage wire does not fix the problem.
Sometimes builders use more than one RF choke and a
vacuum relay to switch the additional choke into the
circuit to arrive at enough inductance to prevent RF
power from entering the power supply at lower
frequencies.
B&W manufactured a successful RFC for amplifiers
called a Type 800 and then a type 802. They had
ceramic cores and fit most chassis situations, but
their wire guage was this and they aren't able to
handle the amperages needed on some big tube
amplifiers.
If you are intrerested in winding your own chokes, the
HAMCALC program available free on the internet
provides a good basis for determining the physical
characteristics.
Hal/W4HBM
On Sat, 06 Aug 2005 03:59:34 +0000 "Angelo Karabetsos"
<ve3yn@hotmail.com> writes:
> Hello,
> I noticed that most plate chokes are wound with very thin gauge wire
> and
> varying diameter. I assume that would make it quite resistive/lossy.
> Some
> are split and mounted at right angles. Is there an advantage to
> using a thin
> gauge conductor other than space considerations?
> 73 VE3YN
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