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Top chassis view of US Signal Corps SCR-211-AF frequency meter set On the photograph the three valves employed in the SCR-211-AF. These have functions as follows: - left hand (glass envelope) valve type 6K8 or VT-167: Detector/mixer; - centre (metal) valve type 6SJ7Y or VT-116-B: Variable oscillator; - left hand (metal) valve type 6SJ7 or VT-116: Audio amplifier. On the right hand side of the chassis are the three power plugs mounted on a paxolin strip, the centre plug being connected to chassis. The trimmer, visible in the right hand corner is the CORRECTOR control, used for corrections in calibration. |
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Top chassis view of USSR CH4-1 frequency meter set The general layout of the USSR CH4-1 is very similar to the USA model, also using a glass envelope valve as detector/mixer, and two metal valves as variable oscillator and audio amplifier. Note the power plugs, fitted on the same position as the BC-221-AF, although the centre chassis connected plug is mounted on the left hand side of the chassis. The CORRECTOR trimmer is similar in shape and fitted in the same place as the USA parent set. |
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Bottom chassis view of US Signal Corps SCR-211-AF frequency meter set The 1000kHz DC-9 type crystal holder is in the centre of the photograph, mounted on a small bracket along with the crystal function switch. The crystal oscillator trimmer (accessible through a hole in the front panel behind the indication plate) can be seen below the crystal holder. |
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Bottom chassis view of USSR CH4-1 frequency meter set In the USSR CH4-1 the 1000kHz crystal holder (round silver coloured unit) is mounted differently and reversed in position. The crystal oscillator trimmer is only accessible from the back of the set through a hole in the crystal oscillator screening cover. The crystal function switch (right of crystal holder) is mounted similarly as in the SCR-211-AF. |