06-14-2014, 10:58 PM
They all had tubes that "did something", (ballasts are not tubes they are resistors), but like the infamous 18 Transistor radios from Hong Kong several decades later they liked to embellish the tube count in various ways. In those they would wire up two or more of the transistors as diodes, they still "did something" but they did not amplify. As far as I know nobody built a set with dummy tubes that did nothing but glow, (other then glass ballasts which are not tubes) but there were plenty of ways to add extra tubes.
Sometimes rather then using a separate triode for the 1st audio, and a dual diode tube for the detector (which many sets connected in parallel) they would use triodes connected as a diode. So instead of using a 6Q7 or a 6R7 they could use up to three 6J5s (or another similar triode), one for the 1st audio, one for the 2nd detector, and another for the AVC/AGC, if it was a set with push pull outputs they could add a fourth 6J5 as a phase inverter. So a company could get a rail car full of 6J5s at a bargain price, and add at least three extra tubes for really no reason at all other then a marketing gimmick.
I suspect this may have been the motivation behind some manufacturers, particularly Brand Z, using dual rectifier tubes like 5Y3s. In the case of their 1940 model year sets they did so with 6X5Gs with disastrous results, not because they were 6X5s but because they exceeded the design specs of the tube. Regardless of what tubes they were pairing up it made little sense as the filament current would end up being higher then just using a single dual diode rectifier with a higher current output.
There are some suspicions about why Canadian Rogers sets used single ended diodes in pairs as rectifiers, like the 2X3 and 2Y3. It may have been for tube stuffing purposes or it may have been as a safety feature in that if one tube burned out the other would not operate as they were in series. Some models had two versions, one with a pair of 2X3s, and one with a type 80, everything else would be the same.
Regards
Arran
Sometimes rather then using a separate triode for the 1st audio, and a dual diode tube for the detector (which many sets connected in parallel) they would use triodes connected as a diode. So instead of using a 6Q7 or a 6R7 they could use up to three 6J5s (or another similar triode), one for the 1st audio, one for the 2nd detector, and another for the AVC/AGC, if it was a set with push pull outputs they could add a fourth 6J5 as a phase inverter. So a company could get a rail car full of 6J5s at a bargain price, and add at least three extra tubes for really no reason at all other then a marketing gimmick.
I suspect this may have been the motivation behind some manufacturers, particularly Brand Z, using dual rectifier tubes like 5Y3s. In the case of their 1940 model year sets they did so with 6X5Gs with disastrous results, not because they were 6X5s but because they exceeded the design specs of the tube. Regardless of what tubes they were pairing up it made little sense as the filament current would end up being higher then just using a single dual diode rectifier with a higher current output.
There are some suspicions about why Canadian Rogers sets used single ended diodes in pairs as rectifiers, like the 2X3 and 2Y3. It may have been for tube stuffing purposes or it may have been as a safety feature in that if one tube burned out the other would not operate as they were in series. Some models had two versions, one with a pair of 2X3s, and one with a type 80, everything else would be the same.
Regards
Arran
