Capacitor types. - UK Vintage Radio Repair and Restoration Discussion Forum

rockinmark · 10th Nov 2014, 8:25 pm

Hi can anybody help what is the deference between capacitor types film / Polypropylene and Polyester iI have a wax one type 346, 200V DC, 0.05uF that needs changing on a valve unit. iI have been looking for a replacement and not sure what to get and does it matter what way round you put it iI believe this would be a near value match 0.047uF 47nF 400V.

Herald1360 · 10th Nov 2014, 8:32 pm

The difference between polyester and polypropylene film capacitors is the insulating plastic film between the two foils. The two films have slightly different characteristics but either will be fine for most coupling/decoupling jobs in a valve set. Polypropylene are "better" and cost a bit more, but for a vintage set, pick the one closest in size/shape to the old part.

AC/HL · 10th Nov 2014, 9:13 pm

And to answer your other questions, it doesn't matter which way round, that only applies to Electrolytics, and .047 is the modern equivalent for the old .05

Radio Wrangler · 10th Nov 2014, 9:26 pm

These sorts of capacitors are non-polarised and will work fine either way round.

Some non-polarised capacitors do have a band around one end. This is to mark which leg is connected to the outer foil just in case the part gets used in some sensitive application and you don't want stray coupling to other components. You'll probably never have trouble with this, but just in case you come across a marked one and wonder about it.

David

rockinmark · 13th Nov 2014, 6:52 pm

Thank you iI have ordered them now iI went for the yellow ones because iI have been told if iI was changing old Hunts these would be good.

10th Nov 2014, 8:25 pm	#1
rockinmark Heptode Join Date: Sep 2014 Location: St Albans, Hertfordshire, UK. Posts: 594	Capacitor types. Hi can anybody help what is the deference between capacitor types film / Polypropylene and Polyester iI have a wax one type 346, 200V DC, 0.05uF that needs changing on a valve unit. iI have been looking for a replacement and not sure what to get and does it matter what way round you put it iI believe this would be a near value match 0.047uF 47nF 400V. Attached Thumbnails

10th Nov 2014, 8:32 pm	#2
Herald1360 Dekatron Join Date: Feb 2007 Location: Leominster, Herefordshire, UK. Posts: 16,535	Re: capacitor The difference between polyester and polypropylene film capacitors is the insulating plastic film between the two foils. The two films have slightly different characteristics but either will be fine for most coupling/decoupling jobs in a valve set. Polypropylene are "better" and cost a bit more, but for a vintage set, pick the one closest in size/shape to the old part. __________________ ....__________ ....\|____\|\|__\|__\_____ .=.\| _---\__\|__\|_---_\|. .........O..Chris....O

10th Nov 2014, 9:13 pm	#3
AC/HL Dekatron Join Date: Nov 2003 Location: Heckmondwike, West Yorkshire, UK. Posts: 9,642	Re: Capacitor types. And to answer your other questions, it doesn't matter which way round, that only applies to Electrolytics, and .047 is the modern equivalent for the old .05

10th Nov 2014, 9:26 pm	#4
Radio Wrangler Moderator Join Date: Mar 2012 Location: Fife, Scotland, UK. Posts: 22,867	Re: Capacitor types. These sorts of capacitors are non-polarised and will work fine either way round. Some non-polarised capacitors do have a band around one end. This is to mark which leg is connected to the outer foil just in case the part gets used in some sensitive application and you don't want stray coupling to other components. You'll probably never have trouble with this, but just in case you come across a marked one and wonder about it. David __________________ Can't afford the volcanic island yet, but the plans for my monorail and the goons' uniforms are done

13th Nov 2014, 6:52 pm	#5
rockinmark Heptode Join Date: Sep 2014 Location: St Albans, Hertfordshire, UK. Posts: 594	Re: Capacitor types. Thank you iI have ordered them now iI went for the yellow ones because iI have been told if iI was changing old Hunts these would be good.