[ARC5] BC-453B capacitors...

[Kenneth G. Gordon]

As several have stated here, you WILL lose other capacitors if you 
run that receiver at full B+ voltage! Period! And, unless you are 
very quick with the off switch, you will lose other, nearly 
irreplaceable, components at the same time.

I tested a bunch of those can-type capacitors in the many ARC-5 
receivers I have here and discovered that most of them show 
significant leakage at 150 VDC. Many fail almost immediately at 
250 VDC. Most of them were originally rated for only 300 VDC, and 
their rating has fallen steadily in the past 60 years.

The one that is most trouble-prone is the three section 0.22 mfd 
cap near the back.

Your oscillation is caused by a screen bypass capacitor being open 
somewhere. The receivers are normally completely stable.

If you MUST run it without replacing any of the below deck 
capacitors, run it at much reduced B+. 

If you do not want to change the appearance of the below-deck 
area, it IS possible to rebuild the can-type capacitors using modern 
components. Although, that job is not particularly easy, in the 
interests of safety to other components, you must either do that, or 
simply replace them with modern disk ceramics, metalized film, or 
"Orange Drop" types, especially if you want to use the original 
dynamotors.

Although Dave Stinson has had good luck running his at 24 VDC, I 
have had varying degrees of success doing that. However, all of 
mine have run well at 130 to 150 VDC.

Lastly, in my experience, the ARC-5 type receivers are possibly the 
finest single-band receivers ever built. 

Other than the capacitor problem, NO DRILLING is necessary to 
get them to work excellently.

Ken Gordon W7EKB