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 Post subject: Soft starting B+ voltage
PostPosted: Mar Fri 12, 2021 8:52 pm 
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Joined: Jan Thu 01, 1970 1:00 am
Posts: 124
Location: Lexington, SC
Restoring a Silvertone 4588B floor model and is playing fine so far as it goes. The B+ voltage however surges past the 450V rating of the caps in the power supply. Surges about 560V from a cold start. Uses a 5X4 rectifier tube that is directly heated and gets ahead of the warmup of the other tubes till the B+ settles out around 375V.

Used an inrush current limiter in series with 5X4 filament. Takes about 30 secs for the radio to warmup but w/o the B+ surge. ICL device is an Amphenol CL-50, 7 ohms at 25C, max current of 5A. The 5X4 rectifier has a 5V 3A filament.

http://www.nostalgiaair.org/pagesbymode ... 017128.pdf


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 Post subject: Re: Soft starting B+ voltage
PostPosted: May Fri 07, 2021 5:25 pm 
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Joined: Jan Thu 01, 1970 1:00 am
Posts: 9637
Location: Latham NY 12110
What filament voltage does the 5X4 see after the warm up?


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 Post subject: Re: Soft starting B+ voltage
PostPosted: May Fri 07, 2021 5:58 pm 
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Joined: Apr Wed 01, 2020 7:22 pm
Posts: 362
I use CL-90s on the incoming AC line to slow the turn-on and drop all the voltages to near where they should be. Todays line voltage is normally in excess of 120VAC, and as high as 126VAC which raises all circuit voltages, adds a lot of unwanted heat, and stresses all of the components...YMMV....73...Jordan VE6ZT


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 Post subject: Re: Soft starting B+ voltage
PostPosted: May Tue 18, 2021 2:39 am 
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Joined: Nov Fri 10, 2006 12:24 am
Posts: 3044
Location: Thornhill, Ontario, Canada
Jordan390a wrote:
I use CL-90s on the incoming AC line to slow the turn-on and drop all the voltages to near where they should be. Todays line voltage is normally in excess of 120VAC, and as high as 126VAC which raises all circuit voltages, adds a lot of unwanted heat, and stresses all of the components...YMMV....73...Jordan VE6ZT
+1 but it runs hot (by design), so try to mount on top of the chassis in some safe, ventilated housing!
Cheers,
Roger

_________________
Roger Jones,
Thornhill, Ontario
Ontario Vintage Radio Assoc. http://www.ovra.ca


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 Post subject: Re: Soft starting B+ voltage
PostPosted: May Sat 22, 2021 5:09 pm 
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Joined: Jan Thu 01, 1970 1:00 am
Posts: 124
Location: Lexington, SC
Lou deGonzague wrote:
What filament voltage does the 5X4 see after the warm up?


My recollection after 2 months is 4V.


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 Post subject: Re: Soft starting B+ voltage
PostPosted: May Sun 23, 2021 12:39 pm 
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Joined: Jan Thu 01, 1970 1:00 am
Posts: 9637
Location: Latham NY 12110
2 months is a long warm up time LOL


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