I have a power supply that I would like to use to power the A supply of my battery radios. Output is 5 volts with no load (there is some variable adjustment here)but how do I determine the amperage? There are no markings to indicate this or what this supply was part of.

This is a DC power supply, right? Is it a linear or switching supply?

Is it fused? That would give you some idea of current capacity.

This would be very crude - but if it's a linear supply, I would weigh it, and guestimate at 10 VA per pound.
Doug

if this is a switching power supply, it may not be the best thing to use on a radio anyway. It makes noise that can be picked up by the radio.

Brian

Switching power supplies will cause noise in a radio.

If the supply is a linear type will work for a radio. Most transistorized supplies shut down when current rating is exceeded. You should be able to determine current by test. Wire 5U4 tube filaments in parallel and see how many will light. Each draws 3 amps.

Norm

:I have a power supply that I would like to use to power the A supply of my battery radios. Output is 5 volts with no load (there is some variable adjustment here)but how do I determine the amperage? There are no markings to indicate this or what this supply was part of.

I've been able to determine (from barely visible markings) a power supply made by Standard Power Inc., model is possibly SPS15-5? Can anyone shred some light on this?

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: : : : : :Sir Brian . . . . : : : :Power supply. . . .POWER SUPPLY. . . . .Step forth and identify thyself ! : :Be ye Linear. . . or be ye Switch Mode ? : : : : : :Initially, considering that the power supply in question is of minimal construction , it being within a molded type of housing and :not being housed and shielded within a metal housing, (Thereby, in the latter case, there being more of a possibility of the :presence of internal RFI (Radio Frequency Interference) countermeasures being contained therein.) : : :Also, your power supply might be in a WALL WART, plug into the wall, style or with a cord that connects to the wall plate. : :A quick type analysis of linear /vs / switch mode. . .can be made via the utilization of a pocket transistor radio. : :Initially it is HIGHLY desirable to have all TV receivers, computer monitors and computers in the immediate area powered down. :Then, take the pocket radio and turn on, tune OFF station at ~550 KC, max its volume and then press the pocket radio right up against the AC wall plate to initially sample any present ambient inteference level on the AC line at that point. : :Then, plug in the Wall Wart ? and press the radio case right up against the casing of the wall wart both in the X and then the Y plane . ( ???. . . .I'm not sure of the positioning of the loop antenna rod / bar within your radio, invariably they end up coincident across the left to right plane of the radio, but a FEW of the smaller flat bar units get placed vertically across an end of the radio.) :That way you have covered both possibilities of having the winding planes of the coils within the Wall Wart and the radios Ferri loop, acquiring maximum coupling in one of those orientations. : :By now, you should know. . . . : : :Was the noise level then increasing up to and becoming a high pitched "Whine" in the radio. . . . you have a switch mode power supply. : : :Or : : :Was the noise level staying the same as a mouse peeing on a cotton ball. . . .then you have a linear power supply. : : : : :Should you be monitoring a switch mode unit, you can detect a slight shift in the "Whines" tone as different loads are subjected upon its secondary. : : :Lately, I have CERTAINLY seen my share of new power supplies being contained within wee housings and still being of a switch mode design, whereas the old style linear still gives a bit of a hint by the contained sizing of the enclosed transformer as well as the coinciding weight factor. : : : :If this is a CORDED power supply. . . of minimal design. . . INSTEAD of the wall wart configuration, you can wrap a turn or two of the AC line around the case of the radio in order to have a like coincidental winding plane coupling to the loop antenna inside. : : : : Finally, I never did come up with an exact schematic of that radio model that you have and "sort" of looked at a #400 model, what is your sets tube line up, or can you provide referencing to its schematic, or at least give me its toobie lineup? : : : : :73's de Edd : : : : : : :

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