05-05-2013, 11:32 PM
I'm not sure about rentals for o-scopes that a restorer would be interested in, although there are companies that rent to corporations. I used to rent them at my last job, but they are very expensive, and they cater to the high-speed digital market. You might be out of luck until you get a complete tube set.
Which tubes are you missing? I understood from one of your posts that you had only the XXLs and the 41s and the rectifier, but if you have the "7" series tubes you should be able to operate the radio and troubleshoot it. I suggested using the scope only as a means to verify the oscillator while you were waiting to buy tubes. If you have filament continuity (which you can measure with your multimeter) you should be able to operate them, so you shouldn't need a scope.
If the radio doesn't play, and you have all the tubes, you can troubleshoot it without a scope, but I don't know any way to verify the oscillator without all the tubes or a scope.
Good luck cleaning the pins and sockets. You could also measure the filament voltages at the tube sockets (as BrendaAnnD suggested above.) If you have voltage on the filament sockets and continuity between the filament pins on the tube, then you probably do need to clean the sockets and pins thoroughly.
If you don't have the pin-outs, you can find them here: http://www.tubedata.info/ Go to the bottom of the page and click on the U.S. flag icon. Navigate through the lists of tubes, and you can download the manufacturers' spec sheets, often several manufacturers for each tube type.
One of your earlier questions was the 16uF vs. 12uF electrolytic. I don't think that change will be a problem. I'm told that capacitor tolerances were all over the map in the old days, whereas today they are closer. The rule of thumb is you can go a little bit higher than the originals, but never lower. Smarter heads that I am can correct me if I'm wrong about that.
On one of my early restorations I accidentally omitted the B+ lead to one of the tubes, and of course the tube didn't work and I got no music. I found it by measuring plate voltages.
You will probably need a signal generator eventually. You can find old ones fairly cheaply on eBay. I aligned my first few radios by peaking the IFs by ear and aligning the AM dials by using radio stations near the frequencies specified in the alignment instructions. It's much harder to do short wave that way, though, because they don't announce their frequencies often, at least not in English.
Which tubes are you missing? I understood from one of your posts that you had only the XXLs and the 41s and the rectifier, but if you have the "7" series tubes you should be able to operate the radio and troubleshoot it. I suggested using the scope only as a means to verify the oscillator while you were waiting to buy tubes. If you have filament continuity (which you can measure with your multimeter) you should be able to operate them, so you shouldn't need a scope.
If the radio doesn't play, and you have all the tubes, you can troubleshoot it without a scope, but I don't know any way to verify the oscillator without all the tubes or a scope.
Good luck cleaning the pins and sockets. You could also measure the filament voltages at the tube sockets (as BrendaAnnD suggested above.) If you have voltage on the filament sockets and continuity between the filament pins on the tube, then you probably do need to clean the sockets and pins thoroughly.
If you don't have the pin-outs, you can find them here: http://www.tubedata.info/ Go to the bottom of the page and click on the U.S. flag icon. Navigate through the lists of tubes, and you can download the manufacturers' spec sheets, often several manufacturers for each tube type.
One of your earlier questions was the 16uF vs. 12uF electrolytic. I don't think that change will be a problem. I'm told that capacitor tolerances were all over the map in the old days, whereas today they are closer. The rule of thumb is you can go a little bit higher than the originals, but never lower. Smarter heads that I am can correct me if I'm wrong about that.
On one of my early restorations I accidentally omitted the B+ lead to one of the tubes, and of course the tube didn't work and I got no music. I found it by measuring plate voltages.
You will probably need a signal generator eventually. You can find old ones fairly cheaply on eBay. I aligned my first few radios by peaking the IFs by ear and aligning the AM dials by using radio stations near the frequencies specified in the alignment instructions. It's much harder to do short wave that way, though, because they don't announce their frequencies often, at least not in English.
John Honeycutt
