AGC capacitor replacement - UK Vintage Radio Repair and Restoration Discussion Forum

petervk2mlg · 4th Mar 2008, 9:32 pm

What voltage rating is OK for replacement AGC line capacitors? I've been using green cap polyesters with a 100 volt rating. However, on reading this from Marcus and Levy Elements of radio servicing , I'm wondering if they are adequate:
"Even though the voltage across (ACG capacitors) is quite low, it is advisable to use a condenser of high voltage rating so that the leakage resistance will be quite large."

Peter

JHGibson · 4th Mar 2008, 9:54 pm

Marcus and Levy wrote that note in the days of paper insulation caps when a higher voltage rating did mean higher insulation resistance. Today's plastic insulated caps have very high insulation value at all working voltages so a 100 Volt cap will be adequate on a AGC line.
John.

Sideband · 4th Mar 2008, 10:19 pm

I agree. I have hundreds of the Mullard/Philips 'licorice allsort' type polyester capacitors (the ones with the value as colour coded stripes) these are rated at either 100v or 250v. Either type are more than adequate for AGC decoupling. Been using them for years with no problems.

Rich.

petervk2mlg · 5th Mar 2008, 7:23 am

Many thanks John and Richard for clarifying this for me.
Peter

4th Mar 2008, 9:32 pm	#1
petervk2mlg Heptode Join Date: Jan 2007 Location: Parkes, NSW Australia Posts: 877	AGC capacitor replacement What voltage rating is OK for replacement AGC line capacitors? I've been using green cap polyesters with a 100 volt rating. However, on reading this from Marcus and Levy Elements of radio servicing , I'm wondering if they are adequate: "Even though the voltage across (ACG capacitors) is quite low, it is advisable to use a condenser of high voltage rating so that the leakage resistance will be quite large." Peter Last edited by petervk2mlg; 4th Mar 2008 at 10:01 pm.

4th Mar 2008, 9:54 pm	#2
JHGibson Retired Dormant Member Join Date: Apr 2003 Location: Salt Spring Island, BC, Canada Posts: 368	Re: AGC capacitor replacement Marcus and Levy wrote that note in the days of paper insulation caps when a higher voltage rating did mean higher insulation resistance. Today's plastic insulated caps have very high insulation value at all working voltages so a 100 Volt cap will be adequate on a AGC line. John.

4th Mar 2008, 10:19 pm	#3
Sideband Dekatron Join Date: Oct 2003 Location: Croydon, Surrey, UK. Posts: 7,567	Re: AGC capacitor replacement I agree. I have hundreds of the Mullard/Philips 'licorice allsort' type polyester capacitors (the ones with the value as colour coded stripes) these are rated at either 100v or 250v. Either type are more than adequate for AGC decoupling. Been using them for years with no problems. Rich. __________________ There are lots of brilliant keyboard players and then there is Rick Wakeman.....

5th Mar 2008, 7:23 am	#4
petervk2mlg Heptode Join Date: Jan 2007 Location: Parkes, NSW Australia Posts: 877	Re: AGC capacitor replacement Many thanks John and Richard for clarifying this for me. Peter