Author Topic: adding fuse to tube radios  (Read 341 times)

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Offline kinkydoints

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adding fuse to tube radios
« on: January 28, 2019, 09:38:57 AM »
in my rebuild of a hallicrafters s120 I would like to add a slow blow fuse to the " hot" side of the main ac line in. what are the factors I need to think about in choosing the correct amp fuse? Should this fuse be the first thing the line in powers up on it's way through the unit.
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Offline The Radio Shop

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Re: adding fuse to tube radios
« Reply #1 on: January 30, 2019, 08:22:28 PM »
Good question. If you pull of the specs you can maximum current draw.
The filaments will draw about 150ma when first powered up, and total will be around 30 watts of power. this is near 4 amps. So a 5 amp fuse should be ok.  I like the fuse before the switch. Remember switches and short also.
Buddy kc4umo

Offline kinkydoints

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Re: adding fuse to tube radios
« Reply #2 on: January 31, 2019, 01:07:50 PM »
without doing more investigating , seen a video that stated the unit runs at about 30 watts. in my study guide for my tech ticket , going sat. for exam here in KY. I noticed a  ...P-I-E ... circle , to help in calculating the different answers , were P is power in watts, E = voltage  dividing to get I = amperes .  called it 130 VAC / 30 =4.34 or so... and ya I did work out that same rated fuse. I will post some pics in the other forum to update this S120. thanks 
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Offline KE4EST

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Re: adding fuse to tube radios
« Reply #3 on: January 31, 2019, 10:45:41 PM »
If it were me I would put the fuse first thing.  Looks like you have already worked out the rating. :)
Michael, KE4EST

Offline kinkydoints

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Re: adding fuse to tube radios
« Reply #4 on: March 20, 2019, 08:57:58 PM »
Thanks guys for this site I am learning from doing more than I ever thought.  I have a question on older tube equipment that have been using these old selenium diode to power the DC side. both of the projects I am working on use these, I have seen the videos on " replacing " these with 1n4007 silicon diode and two electrolytic caps. Can a NTE5301 silicon bridge rectifier be used? that should take 2 caps out of play ?
  just like to update and clean up the underside just a little as far as the rats nest of wires .On these two s-120 hallicrafters radios found two rebuilding one,  the other for a baseline so I don't get lost, as it is untouched by me, the 324 eico . as far as the wave pattern on the 324 would the use of that solid state 5301 rectifier make it a better looking pattern ? the sine wave looks more like a camels back... 


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