Ceramic Resistor
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Location: Golden Grove, SA
Member since 10 April 2015
Member #: 1726
Postcount: 149
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Hi Everyone,
I am after a 150 ohm 20 watt ceramic wire wound resistor.
Is't for the HT circuit for an AWA Valve Amp.
I have bought a Chinese version but would like to get something more original.
Thanks
Josh
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Location: Perth, WA
Member since 19 November 2008
Member #: 381
Postcount: 240
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Location: Golden Grove, SA
Member since 10 April 2015
Member #: 1726
Postcount: 149
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Thanks Gary, The one I got from China looks similar BUT if it doesnt survive and I cant get an original style,
I will look at getting a newer one higher power and putting it under the cover and leave the original in place to look right.
Josh
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Location: Sydney, NSW
Member since 28 January 2011
Member #: 823
Postcount: 6678
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Not usually a good idea to cover a power resistor, especially a 20 watt one.
Why the need to cover it?
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Location: Golden Grove, SA
Member since 10 April 2015
Member #: 1726
Postcount: 149
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I want to keep the top of the amp looking as original original as possible, usually not a huge worry but this AWA is serial number 2 and from what we can figure out a prototype.
The Chinese one should be ok but if not I would use a 50w aluminium covered one bolted to the chassis under the cover it should be ok temp wise
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Location: Wangaratta, VIC
Member since 21 February 2009
Member #: 438
Postcount: 5239
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I have replaced a missing field coil with one of those RS Metal clad ones. In the case of the set there really was not a desirable amount of room however, if you can mount one of them on a side plate, out of harms way (use transistor conductive grease under it), that will assist in dissipating quite a bit of the heat.
Marc
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Location: Golden Grove, SA
Member since 10 April 2015
Member #: 1726
Postcount: 149
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That's the Idea Marc, the other thing is its not like it will be run for long periods, purely for demonstration.
Josh
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Location: Wangaratta, VIC
Member since 21 February 2009
Member #: 438
Postcount: 5239
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I think a lot like HMV changing the screen resistors in the 52 series from 2 x22K 1W Parallel to a 10K seem to forget that W = VIt.
Its that "t" that causes a lot of issues, as in the 10K resistor mentioned slowly failing as I squared R tells us that the current drawn exceeds one watt. We will blame the bean counters & it causes me to stock 10K 2 & 3 Watt just for them.
This is why these things fail, cost cutting seeing underrated inferior parts being used.
I would not dare use anything that would stop the thing being continuous rated (many sets weren't)
Marc
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Location: Sydney, NSW
Member since 28 January 2011
Member #: 823
Postcount: 6678
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