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5E3 grounding and filament questions

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  • 5E3 grounding and filament questions

    I have a Mission 5E3 kit winging its way across the Atlantic at the moment, and I have some questions as I mull over the build in my mind.

    It looks like there is a brass plate included in the Mission kit. How does using this compare to using an isolated jack and pots with a star grounding approach? Is the brass plate problematic or is this really a non issue? Certainly the brass plate allows a neater looking build.

    Also, looking at a few other people's builds, it looks like there is an artificial filament center tap, using 2 x 100 Ohm resistors on the filaments which are "grounded" at one of the power cathodes. I've used this method in a few SE builds and it made a significant reduction in filament hum so I'm all in favour of elevating the "ground". However, the first power socket looks like things are getting a bit crowded on the pins. I have ordered a choke so there will be more stuff (I believe) attached to the first power socket. I notice that some people (e.g. (Steve at S2amps comes to mind) ground the common end of the 2 x 100 Ohm resistors directly to the chassis using one of the socket bolts to mount a small solder tab. This looks like a more elegant method. How much difference (if any) is there between the two system?

    Thanks.

  • #2
    The brass plate is not an issue as long as your connections are mechanically sound and the ground wires go the right places. Solder, the ground wires to the bass plate before you install it in the chassis. Check out the grounding scheme at Hoffmanamps.com.

    If your PT has a centre tap for the 6.3VAC supply you won't need to use a vrtual centre tap. If you do need a virtual centre tap a lot of guys find that the pilot light assembly is a good place to mount the 100ohm resistors.

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    • #3
      Originally posted by MWJB View Post
      The brass plate is not an issue as long as your connections are mechanically sound and the ground wires go the right places.
      Good news.

      Originally posted by MWJB View Post
      If your PT has a centre tap for the 6.3VAC supply you won't need to use a virtual centre tap. If you do need a virtual centre tap a lot of guys find that the pilot light assembly is a good place to mount the 100ohm resistors.
      I haven't received my Mission kit yet but from looking at other peoples pictures I think there is no center tap. I am reluctant to put the 2 x 100 ohm resistors on the back of the lamp because I don't think it looks so neat . I have this crazy idea in my head that this build will be the one where all the leads line up and look neat - I wish.

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