>
>
>
>>>Nothing wrong with the half wave rectifier in the 220...works
>>>fine...lasts a long time. I dont believe in making extra work for
>>myself
>>>particularly for no good reason.
>>>
>>>73....Carl KM1H
>>>
>>For adding a step-start relay and high speed switching, a FWB is
>>indicated. Half-wave rectification causes DC to unhappily flow in the
>>transformer. Adding 3 more diodes and ungrounding the 80v winding is
>>easy/inexpensive.
>>Rich---
>>
>>R. L. Measures, 805-386-3734, AG6K
>
>IMO, adding Step-Start to the SB-220 is a complete waste of time and
>money. The filament xfmr was designed to limit inrush current. The plate
>xfmr is also current limited.
...snip...
- The HV transformer is required to produce repetitive, high peak
currents to satisfy the considerable demand of the C-filter. If the HV
transformer were designed to limit current--like the 220's filament
transformer--the HV regulation would be unacceptable.
- When a stock SB-220 is consistently started up on the SSB HV tap, the
inrush current is such that the life expectancy of the on/off switch is
reduced. Two solutions are: Use the switch manufacturer's 40a inrush-I
version (Arrow p/n 2800HM11 C ) of the switch, or install a step-start
relay.
Rich---
R. L. Measures, 805-386-3734, AG6K
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