Description
''ALL AMERICAN SIX''. (4 metal tubes + 2 glass tubular. All octal base).
RCA model 2 x 61 with TUNED RF Amplifier stage.
The 6 tubes are basically the usual AA5 octal tubes, with the exception that TWO 12SK7 are used, and the rectifier is a 35Z5GT.
Note that the step down transformer is NOT an isolation transformer, meaning that the primary and secondary windings are not isolated from one another. The step-down voltage of 120 Volts is simply ''tapped'' off the primary winding, and that means that 120 Volts AC COULD be present on the radio chassis due to the symmetrical 2 pin American style power plug !
35Z5GT.
12SK7 (x 2).
12SA7.
12SQ7.
35L6GT.
This is an AC/DC radio that operates off 110 VAC, so a 240 volt to 110 volt transformer is required to operate it in Australia.
This would make an excellent AM receiver with its separate RF stage (once the necessary repairs are carried out)
The 35L6GT tube is the audio output tube that connects to the speaker transformer.
The RF Amplifier tube is the 12SK7, and it's worth noting that it's a TUNED RF amplifier (see video).
TUNED Radio Frequency amplifier stage :
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This radio uses a tuned radio frequency amplifier stage.
The difference between a tuned and an untuned Radio Frequency (RF) amplifier stage lies in frequency selectivity.
A tuned RF amplifier uses a resonant LC network to select and amplify only a specific frequency band, whereas an untuned RF amplifier lacks a selective network and provides wideband amplification across a broad spectrum of frequencies.
An UNTUNED RF amp does not filter the input signal. It amplifies everything captured by the antenna within its broad operating limits, including unwanted noise, static, and competing radio stations !
About the ''all American six'' (radio).
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The All-American Six is a transformerless AC/DC superheterodyne receiver that incorporates a sixth vacuum tube—most commonly utilized as a dedicated Tuned Radio Frequency (TRF) pre-amplifier stage..... This addition significantly improves the radio's sensitivity for pulling in weak or distant stations (DXing) and enhances its image rejection capabilities !
ORIGINAL FILTER CAPACITORS IN SINGLE CAN (see in video).
In the RCA Victor 6-tube model 2-X-61 (which utilizes the RC-1080C chassis), the original power supply filtering is handled by a SINGLE multi-section "can" or cardboard-tube style electrolytic capacitor block labeled C19A and C19B on the circuit diagram.
The values for this dual-section electrolytic capacitor are:
• Section C19A: 80 µF rated at 150 Volts
• Section C19B: 50 µF rated at 150 Volts.
As you can see from above, the ORIGINAL electrolytic can from 1950 is STILL IN USE in this radio, and therefore it must be changed ! (The 80 µF can be replaced with a 100 µF, and the 50 µF with a 47 µF).