[ARC5] Homebrew choke

[Brian Clarke]

Hello Neil,

1. If there is the slightest chance that one diode can go
open-circuit, you will then have a true half-wave rectifier. A choke
in series with a half-wave rectifier is a BIG no-no, because of the
back-emf when diode conduction stops on each half-cycle.
2. Ordinary power transformers are not good as HT chokes, because of
the relatively continuous DC flow. You need to open the transformer
and insert an air gap.
3. If you do choose to use a choke to improve regulation, putting it
in the negative lead removes the need for high Voltage withstand.
4. What size (Henries?) and current flow choke do you need? I may have
one that would do.

73 de Brian, VK2GCE On Wed, 17 Aug 2016 15:16:03 +1200, Neil said:

Sorry, I meant a power supply choke with iron core for B+ at 600 VDC.
The scheme is to use a standard old style 230-230 volt (NZ) isolating
transformer for the power transformer. I'm already using one with
full-wave bridge rectifier to derive 325 VDC for my BC-AO-230
transmitter.

Now I want to build a supply using the same transformer for my
AN/ARC-5 transmitter. This will necessitate a voltage doubler circuit
to get 650 VDC (no-load). But because each capacitor in such a circuit
is charged only on alternate half-cycles, with the other supplying
the full load, the regulation, and hum, is going to be a lot poorer
than it is in the full-wave bridge circuit. So I need a choke.

Your experience with the primary of the filament transformer is
interesting. Did you measure, or notice, a significant improvement in
the regulation in a before/after comparison?

NZ house voltage is between 230 and 240 volts, so winding insulation
should be as good or better than the US counterpart.

73 de Neil ZL1ANM

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