[R-390] R-390A Power Transformer, going SS and turn on

[Ken Harpur]

Hi Bill,

That's what I was thinking of doing too...mounting the B+ dropping resistor on the Power Supply unit. That way I can swap Power Supply modules between solid state and tubed at will. The main issue for me was getting rid of some heat and being a little bit nicer to the PT at switch-on.

I have to be honest...I don't like the idea of a CL-80 inside my radio. If I go down this road I'll put one inside it's own box and have it external to the radio. I know a lot of guys like them though. Maybe I'll try that approach also. 

Regards,
Ken


On 5/01/2013, at 3:54 AM, "Bill Breeden" <breedenwb at cableone.net> wrote:

> 
> I have been running a solid stated power supply in my R-390A for a number of years.  Given that I solid stated a second power supply so that I could retain my original power supply with tubes, I mounted the B+ dropping resistor on the power supply chassis instead of the audio module to keep the rest of the radio compatible with a tube type power supply.  The dropping resistor produces a lot less heat than the 26Z5W tubes and I didn't have to modify my working or spare audio module.
> 
> I also have a CL-80 inrush current limiter installed between the AC fuse holder and the AC line filter in place of the original wire between those two points.  It's visually obvious when the radio is turned on that the inrush current limiter is functioning as intended.
> 
> 73,
> 
> Bill - NA5DX
> 
> 1967 EAC #1828       
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