02-01-2009, 01:01 PM
I won't jump into the pinout basing issues commentary but the 5X4 is an easy tube to find on ebay and if you are going to restore the radio having a hacked 5U4 sub as a rectifier tube would diminish the value. From Doug's remarks it should be just a matter of putting the wire connections back, I have a 38-690 and it is a nice radio, been lucky enough to gather a few of Philcos higher tube count 38 models.