03-27-2015, 09:52 AM
One has to tell the hum from the noise reception and home wiring fom AC hum.
Also, 20 same as 70 or 90 is susceptible to the bad aluminum can shields connection to chassis, where the shield is floating rather than shielding.
All my baby grands, as well as other tube radios have at least a little hum, most of it being AC modulated RF, due to home wiring. A pocket transistor radio has the same but then it allows to orient it away from this noise. So is my 46-250 that has a loop type antenna, it also can be oriented out of it.
Grounding may reduce noise also.
Another thing to look for is bad grounding due to oxidized riveting when riveted contacts are used as grounding points.
Also, 20 same as 70 or 90 is susceptible to the bad aluminum can shields connection to chassis, where the shield is floating rather than shielding.
All my baby grands, as well as other tube radios have at least a little hum, most of it being AC modulated RF, due to home wiring. A pocket transistor radio has the same but then it allows to orient it away from this noise. So is my 46-250 that has a loop type antenna, it also can be oriented out of it.
Grounding may reduce noise also.
Another thing to look for is bad grounding due to oxidized riveting when riveted contacts are used as grounding points.
People who do not drink, do not smoke, do not eat red meat will one day feel really stupid lying there and dying from nothing.
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