[Arran]

I don't really like how they denote B- verses chassis ground on these diagram, they use arrows for both, the only difference being that they omitted the lines for the B- ones, it would be very easy to mix the two up. I also don't like it where the have the power line capacitor ahead of the power switch, since it's basically across the power line as long as the set is plugged in.
Regards
Arran

[klondike98]

Yes use of that symbol for B- is confusing.

[RodB]

I use a blue hi-liter to mark the B- on my schematics and pink for B+. Saves retracing time after time.

[MrFixr55]

Hi Klondike,

Unfortunately, there will be leakage.  The culprit is not C5 as this goes to "B-, A-, Common, and only when the switch is on. The Culprit is Cap E1.  This is a "warm chassis" set.  Note the capacitor "E1" is connected between B= and the chassis.  The purpose of this cap is to allow RF energy (i.e. the tuning cap and chassis ground, indicated by the typical ground symbol) to connect to A- / B- (Indicated on the schematic as arrows).  If the cabinet is metal, it appears that the chassis is not well insulated from it.  To make matters worse, like almost every AA5 radio and almost every "3 Way" (AC/DC/Battery) radio, the AC line is "Neutral switched", not "Hot switched"  In other words, the leg of the power cord that goes to the common B- and A- (for battery sets) or B- and 1st AF amp end of the filament string on AA5 and AA6 sets goes through the power switch first.  Therefore, if this leg is at "Neutral" potential, with the switch on, the chassis is at neutral potential (which is ground potential as neutral is tied to ground at your fuse box or meter panel) and you will not feel a tickle (or outright shock) with the switch on.  However, with the switch off, leakage through the rectifier / condensers and tube filaments on this sets or the filament string on AA5 sets will cause the chassis to be "warm".  Using a DVM, you will likely detect 120VAC between the chassis and ground with the switch off and 0V with the switch on.  Reverse the plug and the opposite happens (0V with the switch off, 120V with the switch on.

The issue is not the voltage; it is the allowable current leakage.  It is possible to detect a rather high voltage using a DVM because its input impedance is very high.  Later Sams Photofact schematics instructed Service Techs to measure leakage by measuring voltage across a resistor connected between exposed metal and ground and calculate via Ohm's Law.  if you use a 1K Resistor, the voltage displayed will indicate mA.  For example, 1V across a 1Kohm resistor is 1/1000 Amp or 1 Milliamp (mA), or 1,000 microamp (uA).  The following may help:

• The IEC60601 current specification for most electronics in a patient care area but not having patient contact is 500uA or 0.5mA. 
  

• The IEC61010-1 Standard for consumer electronics is 500uA normal leakage and 3,500uA (3.5mA) for a "single fault" condition.
  

• A "Class A" GFCI (Ground Fault Circuit Interrupter), the type found in most kitchens and bathrooms trips at 4-6 mA (4,000-6,000uA)
  

Of course, what passed UL (Underwriters' Laboratories), or CSA (Canadian Standards Association) inspection in the 1940s and 1950s likely won't cut the mustard today.  Looking at some of the last tube radios of the 1960s, one will find plastic control shafts, no external contact to the chassis, knob clips that prevent removal of the knob from the case and fully enclosed cabinets with very thinly spaced ventilation louvers.

Hope this helps.

[klondike98]

Thanks Mr Fixr. Very helpful as I was actually trying to figure out the best way to check for what that leakage current would be. Next time I'm out in the shop I'll give that a try.

UPDATE: The leakage current is 0.06mA (0.06v across a 1k resistor). Still, I don't like the all metal design and will be on battery when used.

[Arran]

The way I figure it, if you can't feel a tingle with the set turned off then I don't worry about it too much, the .05 uf cap allows a lot less current leakage then a .25 if that many AC/DC sets used to couple the chassis to the B- side. Still, operating the set through an isolation transformer is still an option, though there may be more RF noise.
Regards
Arran

[RodB]

I'm not understanding what you mean by rf noise. Noise is af, we can't hear rf. Maybe you mean it's the noise interference caused by rf. Maybe the noise is somehow modulating an rf signal. I've always been out in right field when it comes to noise interference in our radios. Some handle it much better than others and I'm thinking it may be mainly the antenna design. The power line transmits the noisy signals, the atmosphere transmits noisy signals, politicians transmit noisy signals. It's up to antenna design to reject them.

[MrFixr55]

The only antenna that can filter out politicians is no antenna and the set in a Faraday cage.

Strong RF can modulate and heterodyne the signal. For example, when I was a kid, I could hear squeals on an AM radio when the TV was on, even a battery operated transistor radio. It would get lower if I walked outside bad louder when passing a neighbor's house when their TV was on. The noise that I hear in my house with some of these radios is relatively low in frequency. I can't exactly put my finger on it as 60 Hz hum, and I don't think that it is 120Hz hum, at least not coming from the various radios, and they all behave the same except for some of the newer sets that have ferrite loopstick antennas. My house is wood, shingled on 3 sides, aluminum siding on one side (the west facing side and most stations in my area are west of here in NYC), wired in Romex with no conduit other than the service drop mast. If I get away from the house, even if using AC from the house, like in the back yard, the signal is somewhat cleaner. My 50 ft log wire antenna is of no help.

[klondike98]

I can finally put this one to bed. I got ahold of some of the large snaps used for the Eveready 467 battery and was able to complete the restoration. Its together now and playing nicely. Thanks to everyone for all the help along the way!! I have another battery set coming in a few days...the adventure continues...

[Image: https://www.dropbox.com/scl/fi/ft2fk5ofj...hxua&raw=1]

[Image: https://www.dropbox.com/scl/fi/b7j0f0mnc...6ben&raw=1]

[Arran]

Bob;
I have a soft spot for battery radios, especially the farm sets. The ones that had in Canada had such cabinets, and were decent performers, most having an extra RF or IF amplifier stage, just what people needed in an underpopulated country, with long distances between settlements. What I like the most is the fact that I may be the first person to hear the set play in 60 or 70 years, since they were often put into storage after AC mains came into an area. Needless to say three way portables usually got way more use then their DC only siblings.
Regards
Arran

[klondike98]

I’ve tended to stay away from battery sets for the most part but really enjoyed getting a Crosley 1121 and a speaker up and running and this little Motorola was similarly fun to hear play. I have an Emerson 560 coming that is battery only that will be the next project. I do get a thrill hearing the restored sets play for the first time in decades.