> Hopefully the answers you post will be more detailed than: > "It depends", "Maybe", or "Yes and No".
Hi Bob (and the group) Then your probably not going to like my answers very much... > So today's questions are (in your experience): > 1. Does the supply just fold-back the current if the output > is shorted? In the generic sense to the majority of fixed voltage supplies sold and used for the typical ham station, NO they do not safely fold back current in shorted conditions. But some Astron Supplies do properly fold back based on their date of production, size/ capacity and model. And, it is not super rocket science to add a current fold back control because the heart of the circuit is already (mostly) in place on the regulator board. > 2. Does the supply just fold-back the current if the crowbar > SCR fires? The SCR fire was/is traditionally included to blow a fuse in a catastrophic condition. Protect the equipment was job 1. > 3. Can anything simple be done to prevent the crowbar from firing > when the supply operates in a strong RF environment? Yes, change some of the parts out to different values, add one or two parts (caps and resistors) and depending on the age of your specific regulator board/supply change some of the part(s) connection points/locations. Someone with a working but cranky supply could Email me and based on a list of about 10 questions I would ask... be able to help me identify the regulator board version in their supply. I'd then be able to tell then what specific parts value to change and what parts to add & where they would go. But some of the early regulator boards are not realistic or practical to patch upgrade. > 4. Is the crowbar firing due to RF, or is the output voltage > actually going high enough to trip the SCR, thus making it > fire for the purpose it's there for? Depending on the regulator board (supply) version, the problematic SCR fire issue is primarily related to wrong (not the best) part value selections, RFI and transients getting in the trigger circuit. More questions...? Got milk? cheers, s
