IIRC, the difference is (from a 5U4) that there's a cathode, with a heater.? Some of the other ones have a heater only.? Whether the heater is isolated or not, I don't remember.? Unless the requirements are for an isolated cathode, you may be ok.? A quick look at the pinouts for the 5U4 and 5AR4 would verify this.
Harvey
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On 8/31/2019 5:45 PM, Phillip Potter wrote:
Hi Chuck,
While I was reading your comment to Jamie, I note with interest your suggestion that a 5AR4 is of little demand.? This tube number jogged my memory, and I found it easily in the Service Manual for my HP 200CD Signal Generator, where it is employed as a rectifier tube... I'm hoping that you're right about that, because I could use one for a spare. ;)
Phil
On 8/30/2019 6:45 PM, ChuckA wrote:
BTW a workable replacement for the 5AR4 is a 5V4 again a TV damper tube and very little demand outside of the TV collector community.
