E52b/7 - Page 3

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This is my first Köln. When I received it, the outside was very fine with new paint
and new marking. But it did not work well. All the modules can be plugged out and
tested separately. All the parts were OK but the radio did not work properly.
After long time of investigation I found out that the Q of the HF resonant circuits was low.
Then I found out that the problem was the 6-gang tuning capacitor.
The capacitor was full of dirt.


Tuning mechanic and oscillator capacitor.

This Köln E52b-7 has the same tuning mechanic as the E52a with motor tuning but without motors.
All gears have anti backlash mechanisms.

All the modules are here removed for cleaning from the chassis.

The capacitor was removed from the chassis and rinsed in alcohol for a week.

The clean capacitor is here replaced.

Here is the anti backlash gear. It is not easy to find the right position of the gear.

Frequency scale is here mounted. The oscillator capacitor shaft is connected directly to
the frequency readout scale. The frequency readout microfilm is also connected to this shaft.


RF amplifier no. 1

RF amplifier no. 2

Oscillator and mixer


First and second tuned circuit’s module.

Here is one of the six-band switches.

Tuned circuit’s no 3 and 4.

Tuned circuit’s for oscillator and mixer


Frequency readout optic. From LA8AK’s page.

Frequency readout optic and mechanic.

Frequency readout optic and mechanic with adjustment screw.

Rodenstock-Ronar 1:1.8 – f 1.2 cm, Lens

Lens and filtermask.

Frequency readout mirror.

Here is the glass-microfilm with all frequencies mounted.
The microfilm is mounted on the oscillator capacitor shaft.
Each number is extremely small. The width is only 12 um.
Each frequency band has a track witch contain all numbers.
Optic is mounted over the microfilm. A shaft connected to
the band-selector lift the optic to right track on the microfilm.

Here is also the coarse scale mounted. This scale is also mounted on
the oscillator capacitor shaft.