CLC High Pass T Filter Rotary Switch Pole count

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LazyTurtle

Active member
Joined
Apr 18, 2017
Messages
43
Hi, after checking several schematics I´m trying to figure out why is a 3 pole rotary switch placed in most designs I´ve seen.

For example, for a CLC high pass T filter the rotary switch should connect to both capacitors for each frequency, but the multitapped inductor would share common GND with all the stages.
So, for a 6 frequency steps HP T filter, wouldn´t a 2P6T  switch be enough? Check the attached image.


Thanks
 

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I think the altec 9067b is designed following this topology...
I´ve checked several new high pass filters  based in the Altec and also think they have that topology.
 
You can check this topic where this type of rotary switch is mentioned:

https://groupdiy.com/index.php?topic=51217.0

As you can see the switch seems to be 3 pole...but I still don´t get why...
 
LazyTurtle said:
You can check this topic where this type of rotary switch is mentioned:

https://groupdiy.com/index.php?topic=51217.0

As you can see the switch seems to be 3 pole...but I still don´t get why...
Where can I see that? There is no schematic and the pictures are extinct.
 
This is the picture of a unit a built several months ago.
It is a unit bought as a DIY Kit.
This is a CLC T filter and as you can see (hope it is clear enough) the rotary switch uses three decks (yellow, black and green cables, one colour per deck).
 

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LazyTurtle said:
It is mentioned in the post itself.
Search for the "switch" word.
Why not saying which post? I had to read the whole thread to find the shade of an answer in post #19.
It looks like Altec used a particular arrangement that needed a 3rd switch. See attachment.
I don't know why they would use this arrangement; I can't imagine one second their engineers overlooked the simpler 2-wafer arrangement.
My only guess (but it should be substantiated with more hard evidence) is this arrangement has less interaction between sections if there are pull-down resistors.
 

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Thank you very much for all the valuable information, and sorry for the reference to the post I sent.
I thought maybe searching for "switch" in the topic you could've reached faster to the post itself.
 
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