Parmeko AP67914 voltage rating - UK Vintage Radio Repair and Restoration Discussion Forum

valvo_lk4330 · 23rd Jan 2018, 3:44 pm

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

Herald1360 · 23rd Jan 2018, 4:55 pm

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.

turretslug · 23rd Jan 2018, 6:27 pm

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.

valvo_lk4330 · 6th Mar 2018, 9:57 am

Chris,

Would you want to have it at home that way?

Rgds

valvo_lk4330 · 6th Mar 2018, 10:03 am

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

M0FYA Andy · 6th Mar 2018, 10:42 am

Quote:

Originally Posted by Herald1360

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.

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..............

trobbins · 6th Mar 2018, 9:51 pm

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 ?

joebog1 · 6th Mar 2018, 11:32 pm

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

valvo_lk4330 · 10th May 2018, 2:26 pm

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

trobbins · 12th May 2018, 4:53 am

Just be mindful of hum:
Note on a cause of residual hum in rectifier filter circuits. Terman & Pickles, 1934.

23rd Jan 2018, 3:44 pm	#1
valvo_lk4330 Retired Dormant Member Join Date: Jan 2018 Location: Vienna, Austria Posts: 6	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
Herald1360 Dekatron Join Date: Feb 2007 Location: Leominster, Herefordshire, UK. Posts: 16,535	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. __________________ ....__________ ....\|____\|\|__\|__\_____ .=.\| _---\__\|__\|_---_\|. .........O..Chris....O

23rd Jan 2018, 6:27 pm	#3
turretslug Dekatron Join Date: Nov 2011 Location: Surrey, UK. Posts: 4,393	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.

6th Mar 2018, 9:57 am	#4
valvo_lk4330 Retired Dormant Member Join Date: Jan 2018 Location: Vienna, Austria Posts: 6	Re: Parmeko AP67914 voltage rating Chris, Would you want to have it at home that way? Rgds

6th Mar 2018, 10:03 am	#5
valvo_lk4330 Retired Dormant Member Join Date: Jan 2018 Location: Vienna, Austria Posts: 6	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, 9:51 pm	#7
trobbins Heptode Join Date: Oct 2009 Location: Melbourne Australia Posts: 901	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
joebog1 Banned Join Date: Jun 2015 Location: Mareeba, North Queensland, Australia Posts: 2,704	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
valvo_lk4330 Retired Dormant Member Join Date: Jan 2018 Location: Vienna, Austria Posts: 6	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
trobbins Heptode Join Date: Oct 2009 Location: Melbourne Australia Posts: 901	Re: Parmeko AP67914 voltage rating Just be mindful of hum: Note on a cause of residual hum in rectifier filter circuits. Terman & Pickles, 1934.