model 84b - Printable Version

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+--- Thread: model 84b (/showthread.php?tid=18167)

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RE: model 84b - Radioroslyn - 04-02-2018

>are you running a polarized plug ensuring the hot is switched?
No, You can if you like not a big deal. I don't particularity like them as they don't fit into some receptacles.

> but it seems that 10mfd  50vcap from the ct to ground (28) wouldn't be too happy if you didn't,especially as the chassis must be grounded.
Well the 10 mfd doesn't care at all about the mains polarization as it is isolated thru the power transformer. It's strictly there to filter the negative dc voltage. The other part of 28 (.015) on the primary of the transformer gives the chassis a rf ground thru the neutral side of the mains. It's better to connect an earth ground (one not related to the mains ground or neutral) as the mains can carry a lot of noise.

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RE: model 84b - falcon123 - 04-03-2018

perhaps i misunderstood,im still not used to the idea of philcos attempts at the worlds first IC! i was on the wrong side of the transformer! forgive my ignorance! by the way what are your thoughts on coating the transformer coils with polyurethane? mine all read good.

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RE: model 84b - Radioroslyn - 04-03-2018

>forgive my ignorance!
No problem! I find myself on the wrong side of a transformer every once and a while too!

>your thoughts on coating the transformer coils with polyurethane? 
Not sure what effects it may have on the efficiency (known as Q of a coil). By lowering the Q it can foul things up, Oscillators won't oscillate, poor sensitivity, and poor selectivity.
I would stick with wax, nothing, or just a bit of lacquer. I'm thinking that getting rid of the original plastic strip is a big help to alleviate the rot problem.

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