Just some general guidelines when choosing a linear power supply for long-term receive-only use ...
It simplifies trying to figure out all the "ICAS" ratings and whatnot, usually intended more for transmitting needs. Long term rx-only is very simple.
Don't exceed 25% of the total rated amperage of the supply. That means warm, not HOT. Warm is where you can leave your palm on the heatsink all day long - you'll feel it for sure, but you can leave your hand there. HOT means you simply can't leave your palm on the sink for more than about 10 seconds. Components will last longer without having to run ice-cold if you don't exceed 1/4 of the total rating.
This is even more important if the ambient temperature of the shack is hotter than 77F.
Example: My HF transceiver, used for rx-only, pulls about 1.4 amps max. With that, I use a 7-amp linear supply. Heatsinks are warm, but not hot. I tried the same with a smaller 4A rated supply, and I just exceeded 25% by a little bit. OUCH! Sure, the 4A supply is a little toasty, and is built to dissipate heat, but I want to extend the life of the components.
*** WARNING ***
If you feel your heatsink, DO NOT WEAR ANY RINGS doing this. Why? If you short the exposed power transistor case to the heatsink, you can damage the supply, especially if they don't have any other protection circuitry.
Considerations: If you have some really expensive gear on that supply, you may want to choose one that has "crowbar" protection. That usually means if something goes wrong and you lose regulation, it will trip the supply, and not let the unregulated 18 to 24v through to the radio.
What causes this? Massive overloading and/or very high ambient temps can cause this. Maybe not right after purchase, but later down the line. Power line spikes can also do this.
Protect the input to the supply: Some supplies incorporate a single transient MOV or other parts inside the supply. That's fine. But I STILL recommend an external unit, like a Tripp-Lite Isobar to do a much better job of that. Especially for the smaller supplies that don't incorporate a crowbar protection circuit.
It really is that simple - go big if you want to run ice-cold, or envision adding more gear to the supply later on. Or perhaps you need a feature, like a built-in crowbar that sometimes comes only with larger supplies.
Of course, if you want to take the whole thing to the next level, there's always this:
Astron Power Supply Index Page
Astron or not, it's a great resource.
It simplifies trying to figure out all the "ICAS" ratings and whatnot, usually intended more for transmitting needs. Long term rx-only is very simple.
Don't exceed 25% of the total rated amperage of the supply. That means warm, not HOT. Warm is where you can leave your palm on the heatsink all day long - you'll feel it for sure, but you can leave your hand there. HOT means you simply can't leave your palm on the sink for more than about 10 seconds. Components will last longer without having to run ice-cold if you don't exceed 1/4 of the total rating.
This is even more important if the ambient temperature of the shack is hotter than 77F.
Example: My HF transceiver, used for rx-only, pulls about 1.4 amps max. With that, I use a 7-amp linear supply. Heatsinks are warm, but not hot. I tried the same with a smaller 4A rated supply, and I just exceeded 25% by a little bit. OUCH! Sure, the 4A supply is a little toasty, and is built to dissipate heat, but I want to extend the life of the components.
*** WARNING ***
If you feel your heatsink, DO NOT WEAR ANY RINGS doing this. Why? If you short the exposed power transistor case to the heatsink, you can damage the supply, especially if they don't have any other protection circuitry.
Considerations: If you have some really expensive gear on that supply, you may want to choose one that has "crowbar" protection. That usually means if something goes wrong and you lose regulation, it will trip the supply, and not let the unregulated 18 to 24v through to the radio.
What causes this? Massive overloading and/or very high ambient temps can cause this. Maybe not right after purchase, but later down the line. Power line spikes can also do this.
Protect the input to the supply: Some supplies incorporate a single transient MOV or other parts inside the supply. That's fine. But I STILL recommend an external unit, like a Tripp-Lite Isobar to do a much better job of that. Especially for the smaller supplies that don't incorporate a crowbar protection circuit.
It really is that simple - go big if you want to run ice-cold, or envision adding more gear to the supply later on. Or perhaps you need a feature, like a built-in crowbar that sometimes comes only with larger supplies.
Of course, if you want to take the whole thing to the next level, there's always this:
Astron Power Supply Index Page
Astron or not, it's a great resource.
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