"wb5kcm" wrote in message
ups.com...
My Ranger is blowing the 5 amp primary fuse every once in a while when
I turn it on. I have checked for any kind of intermittent short but
unable to find anything. I am now suspecting inrush current. My Ranger
has all the power supply mods. Solid state HV and LV power supplies
with 330mfd LV cap and 165mfd HV cap. At first did not suspect inrush
current due to having choke input filters but I suppose with the solid
state rectifiers and the large caps it maybe happening. Does anyone
have any suggestions to limit this inrush current in the Ranger. Also,
does anyone know what the Ranger's nominal current consumption is from
the 117 VAC source under full load? Any info is appreciated. 73, Randy

You probably would find a varistor in the primary of the transformer to be
of help. It also improves the life of the power on-off switch at the same
time.
We used one in the primary of the Signal One transceivers after having
measured an one cycle inrush current in excess of 50 Amperes! (Hypersil core
transformer) You can purchase them that exhibit a hundred Ohms or so when
cold that drop to 4-6 Ohms hot and essentially remove themselves from the
circuit after the first few moments of operation. They don't help at all if
you turn the radio off after a period of use and immediately power it back
up whilst the varistor is still hot, but it takes the edge off the inrush
curent in "normal" operation. About the size of 3-4 nickels stacked together
with a radial lead off each face.

W4ZCB