Just picked up a 1930s Battery operated Coronado

[old_tv_nut]

Note that later and more expensive scopes may have built in measurement cursors to get a more precise measurement of time/frequency than just eye-balling the display, but eventually these have to be calibrated against a standard frequency source.

Really modern scopes are all digital sampling types, and the sampling rate is crystal controlled, so the scope really contains a calibrated reference.

[vortalexfan]

Originally Posted by old_tv_nut

Note that later and more expensive scopes may have built in measurement cursors to get a more precise measurement of time/frequency than just eye-balling the display, but eventually these have to be calibrated against a standard frequency source.

Really modern scopes are all digital sampling types, and the sampling rate is crystal controlled, so the scope really contains a calibrated reference.

Ok, that makes sense. Thanks for explaining that to me.

[vortalexfan]

OK, so a little update: This radio had been working like a champ for the past week and a half and then today I was listening to it and the stations were bleeding over onto each other on the upper end of the dial and so I turned it off and went to turn it back on to see if it had cleared up the issue and for some reason or another I can't get it to turn on anymore, and I noticed that the power switch was a little finicky sometimes and would require me to turn the power knob a couple of times before it would finally turn on, but now its not turning on at all period except for a little crackling noises when I would turn the power switch on and off several times and then turn it on and wait for it to warm up, but I'm not getting any audio.

I'm thinking its the power switch, because I have a Philco 116B that's done the same thing with its power knob, except instead of sticking in the off position like this one seems to be doing it sticks in the on position.

and the switch that this farm radio uses has 2 sets of contacts in it rather than one set like your traditional AC power switches, one set of contacts is for powering on the B+ power and one is for turning on the A+ (Filiment) power and I'm not sure where I would get a new switch like that or if I could take the switch apart and clean the contacts and lubricate them and see if I could get the switch freed up and working again.

And no its not the batteries because I just installed a set of freshly recharged "D" batteries in the "A" Battery pack and the "B" batteries are still putting out a solid 89.5 Volts DC.

Any help would be appreciated.

Thanks!

[init4fun]

Your next step should be to disconnect the A and B wires from the switch (with the batteries disconnected) and connect the A and B supply's wires together in the proper way that the switch connects them when it's on . Then reconnect the batteries . If the radio plays , your switch is bad . If not , your gonna be looking for other problems .

[vortalexfan]

Originally Posted by init4fun

Your next step should be to disconnect the A and B wires from the switch (with the batteries disconnected) and connect the A and B supply's wires together in the proper way that the switch connects them when it's on . Then reconnect the batteries . If the radio plays , your switch is bad . If not , your gonna be looking for other problems .

So how do I do that?

[Electronic M]

Instant on in battery sets is typically a function of the extremely short warmup time of filament type battery tubes.

[vortalexfan]

Originally Posted by Electronic M

Instant on in battery sets is typically a function of the extremely short warmup time of filament type battery tubes.

Ok, so I'll just check a few other things then.

[dieseljeep]

Originally Posted by vortalexfan

Ok, so I'll just check a few other things then.

Just disconnect the battery when not using it!
Batteries are expensive and when though showing it and how well it works, It isn't that difficult and it will give you piece of mind.

[vortalexfan]

Originally Posted by dieseljeep

Just disconnect the battery when not using it!
Batteries are expensive and when though showing it and how well it works, It isn't that difficult and it will give you piece of mind.

Ok, well I didn't realize that the radio was still drawing current from the batteries even when its turned off, because I know modern transistor radios don't usually draw current from a battery when its turned off.