I just finished a complete rebuild on my? PS 150-120.? I choose to stay with a 2 prong polarized power cord mostly due to Walter Cates recommendation to avoid 60hz hum on the TX.? ?Didn't see why at first but I think I've codgertated it out.? ?The TRX? and PS were designed together and? the TX is intended to be the common signal ground point for both.? With? a 2? prong polarized plug and cord this works fine but will not support a GFI.? ?
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If you add? a? 3 prong? cord to? the PS the 60hz current passed? by C201 and C202 appears on the electrical Ground and can be passed to the electrical Common via the main AC breaker box? where the 2 are terminated to the same buss.? ?This can appear as a 60hz potential between a station RF ground and the electrical Common which apparently can find it's way into the TX audio.
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This is no doubt highly situational depending? on house and station wiring.? ?If you use a 3 prong AC cord and encounter the hum, deleting C201 and C202 might fix it.? Also the 60hz current passed onto the electrical Ground by the capacitors? could? trip a GFI considering that is the current they are intended to sense.??
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A ferrite on the power cord can functionally? replace? the caps.
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73 Jack KZ5A
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