Ekco U245 metal caps - UK Vintage Radio Repair and Restoration Discussion Forum

Daventry 5XX · 10th Feb 2012, 2:30 pm

Hi all

I'm in the process of recapping an Ekco U245 (trader sheet no.1309)

I've come across 2 metal caps which in my limited experience I'm not familiar with.

The first is C23 0.01mf which has a small tag connecting the outer case to chassis

The second is C27 0.005mf (the list says it should be 0.002 but it looks original) This one has insulation wrapped around the body to prevent contact with anything else.

They dont appear to be polarised and are not shown as electrolytics on the circuit diagram

My question is, can I replace these with standard polypropylene caps or do they have to be metal cases,and why are they metal cases anyway?

Whats the difference between these and standard caps?

Any advice very welcome

Alan

ukcol · 10th Feb 2012, 3:04 pm

Hi Alan

C23 couples the audio to the first valve in the audio amplifier. Thsi is where the audio gain is maximum and an area that can be vunerable to hum pick-up. I would think though that you could use a "normal" capacitor provided you keep it away from the mains switch wiring and any other AC wiring.

I can't see any reason to insulate C27, there are no particularly high voltages on it.

Colin M

10th Feb 2012, 2:30 pm	#1
Daventry 5XX Pentode Join Date: Dec 2011 Location: Daventry, Northamptonshire, UK. Posts: 163	Ekco U245 metal caps Hi all I'm in the process of recapping an Ekco U245 (trader sheet no.1309) I've come across 2 metal caps which in my limited experience I'm not familiar with. The first is C23 0.01mf which has a small tag connecting the outer case to chassis The second is C27 0.005mf (the list says it should be 0.002 but it looks original) This one has insulation wrapped around the body to prevent contact with anything else. They dont appear to be polarised and are not shown as electrolytics on the circuit diagram My question is, can I replace these with standard polypropylene caps or do they have to be metal cases,and why are they metal cases anyway? Whats the difference between these and standard caps? Any advice very welcome Alan

10th Feb 2012, 3:04 pm	#2
ukcol Rest in Peace Join Date: May 2003 Location: Harlaxton, Lincolnshire, UK. Posts: 3,944	Re: Ekco U245 metal caps Hi Alan C23 couples the audio to the first valve in the audio amplifier. Thsi is where the audio gain is maximum and an area that can be vunerable to hum pick-up. I would think though that you could use a "normal" capacitor provided you keep it away from the mains switch wiring and any other AC wiring. I can't see any reason to insulate C27, there are no particularly high voltages on it. Colin M