I think PSUD assumes the full load is there at
startup unless you set a delay. Normally, the cold valve does not
conduct for a few seconds. The anode resistors are calculated for
full voltage and current, so the transformer winding is normally
enough on its own. If a cathode follower is involved and you are
using NOS valves, watch the cathode-heater voltage. The modern
6922 equivalents have a much higher rating.?
Richard
On 24/09/2024 08:48, Duncan Munro
wrote:
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Hi Pierre,
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PSUD2 should be able to deal with this for you. If you
measure the leg of the transformer at 70 ohms, simply add the
required resistor value (100 ohms) to give your secondary of 170
ohms.
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Double click on the transformer icon to access the
transformer properties box:
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The press the [...] button shown by the arrow. This will
bring up the Source Impedance Calculator:
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Enter your off load voltage on one leg and the winding
resistance, again for one leg. In reality, you may find the two
secondary legs have a different resistance so just average two.
Note that I've used 170 which is 70 plus the 100 extra. PSUD (in
this example) calculates the source impedance as 230.6 ohms,
however it is taking the effect of the primary into account too.
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Click OK and it will feed the transformer parameters back to
PSUD2 and you're good to go.
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Having a small input cap on CLC filters is OK, it helps to
increase the conduction angle and reduce the peak current in the
rectifier. Hope this is helpful.
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Regards,
Duncan
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