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Components and Circuits For discussions about component types, alternatives and availability, circuit configurations and modifications etc. Discussions here should be of a general nature and not about specific sets. |
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23rd Jan 2018, 3:44 pm | #1 |
Retired Dormant Member
Join Date: Jan 2018
Location: Vienna, Austria
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Parmeko AP67914 voltage rating
Dear Group,
i have sent yrs to mate two of PARMEKO Chokes 20H/80mA labelled Neptune Series AP67914 Ser. No. PMA 1/51 I have that 211 SE Project here, but i am unsure whether it will take 1kV steady. I have seen other models labelled 1.4kV pk having longer ceramic terminals. I am sure on 500-600 Volts, but double that? thanks in advance, Anton |
23rd Jan 2018, 4:55 pm | #2 |
Dekatron
Join Date: Feb 2007
Location: Leominster, Herefordshire, UK.
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Re: Parmeko AP67914 voltage rating
If these are in metal cans, why not isolate the can from chassis and restrict access? The EHT voltage won't be across the choke winding, just from winding to case/chassis.
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....__________ ....|____||__|__\_____ .=.| _---\__|__|_---_|. .........O..Chris....O |
23rd Jan 2018, 6:27 pm | #3 |
Dekatron
Join Date: Nov 2011
Location: Surrey, UK.
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Re: Parmeko AP67914 voltage rating
Is there scope for connecting the choke(s) in the negative side of the HT supply, i.e. close to the 0V side of things? I'm assuming that any pi-filtering capacitors will be separate items at this sort of voltage, rather than multiple-section-with-common-negative types. Putting HT chokes in the positive side of the supply is a convention used with multiple-section capacitors that seems to have stuck when otherwise un-necessary and is stressful of insulation. Also, negative-side fitment can sometimes be used for bias derivation, depending on circuit.
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6th Mar 2018, 9:57 am | #4 |
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Location: Vienna, Austria
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Re: Parmeko AP67914 voltage rating
Chris,
Would you want to have it at home that way? Rgds |
6th Mar 2018, 10:03 am | #5 |
Retired Dormant Member
Join Date: Jan 2018
Location: Vienna, Austria
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Re: Parmeko AP67914 voltage rating
That is an Option but it will change grounding. Usually referenced to Input cap it will likly be in the output Cape negative for audio ground.
Opinions? rgds |
6th Mar 2018, 10:42 am | #6 |
Nonode
Join Date: May 2007
Location: Preston, Lancashire, UK.
Posts: 2,511
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Re: Parmeko AP67914 voltage rating
The power supply for the H2S radar used that method in the +/- 1800v circuit. The chokes are mounted on bakelite supports with one terminal connected to the laminations so the whole choke sits at 1800v. Just don't touch it..............
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6th Mar 2018, 9:51 pm | #7 |
Heptode
Join Date: Oct 2009
Location: Melbourne Australia
Posts: 901
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Re: Parmeko AP67914 voltage rating
Is there only negligible AC across the choke winding?
You could stress test it, and then fall back to 1kV working voltage, and make sure the power transformer secondary is fused. That is then a functional specification if nothing else. Do you have an insulation resistance meter that generates at least 1kVdc ? |
6th Mar 2018, 11:32 pm | #8 |
Banned
Join Date: Jun 2015
Location: Mareeba, North Queensland, Australia
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Re: Parmeko AP67914 voltage rating
Why not put the choke in the ground leg of the power supply?
That way it doesnt have a large voltage across it at all. Joe |
10th May 2018, 2:26 pm | #9 |
Retired Dormant Member
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Location: Vienna, Austria
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Re: Parmeko AP67914 voltage rating
That came a lot cheaper than insulating the windings to the core as that voltage even exceeds the bobbin rating and therefore need for switching to bigger core...
Anton |
12th May 2018, 4:53 am | #10 |
Heptode
Join Date: Oct 2009
Location: Melbourne Australia
Posts: 901
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Re: Parmeko AP67914 voltage rating
Just be mindful of hum:
Note on a cause of residual hum in rectifier filter circuits. Terman & Pickles, 1934. |