nordmende: Ch=2/632; Othello-Stereo

Hi,

Radio Nordmende   Md. Othello-Stereo Ch=2/632    ID 23821

With a schematics of Rmorg  I had start work in that radio, after remove/change  a few capacitor and change some tube it’s start work. with a big sound not quality!

I need to confirm the good align of the IF tuner’s, in order to increase a good signal/sound, but the original doc is in German and the automatic translation in PC do not work  right  ( not work ).

Is possible someone (a good person)  translate  for English !!??

For all community Thanks

Hernani Capela

To thank the Author because you find the post helpful or well done.

Perhaps this will help. 

Translation of the text at the top of the first page of alignment instructions ( d_nordmende_1962_othello_stereo_abgl1.pdf ).

Alignment instructions for AM

IF 460 kHz

Push button "M" -- Turn tuning capacitor to the left end of the dial (1650 kHz).  Set the bandwidth to "narrow" by pulling out on the left outer knob.  Turn up the volume all the way.  Set the tone to "Hell" ("bright").  Couple a signal generator via a dummy antenna (200 pF capacitor and 400 ohm resistor in series) to the control grid of the ECH81.  Connect an output meter to pins 1 and 2 of socket (15) or (16).  First detune IF circuits II, IV, and V.  Then tune IF circuits I, III, and VI for maximum signal.  Then tune circuits II, IV, and V for maximum signal.  Connect the dummy antenna to the antenna and ground terminals and adjust the IF trap for minimum signal strength. 

Be sure to follow the prescribed order for the following adjustments:

Medium wave ferrite antenna

First push button "PA."  Turn tuning capacitor to the right end of the dial (515 kHz), and set the pointer position to line up with the end mark on the dial.  Set the dial to 555 kHz and adjust oscillator coil a and  compensation coil c for maximum signal.  Tune the dial to 1480 kHz and adjust oscillator trimmer b and antenna trimmer d for maximum signal.  Repeat these adjustments until no further improvement is possible.

Medium wave external antenna

Release push button "PA."  Set the dial to 555 kHz and adjust front end coil e for maximum signal, and then set the dial to 1480 kHz and adjust front end trimmer f for maximum signal.

Long wave

Push button "L."  Tune the dial to 210 kHz and adjust oscillator coil g and front end coild h for maximum signal.  (For technical reasons, there is no adjustment of the long wave ferrite antenna.)

Short wave

Push button "K."  Set the dial to 6.1 MHz and adjust oscillator coil i and front end coild k for maximum signal.  The oscillator frequency should be above the receiving frequency.  The image of 6.1 MHz appears at 7.02 MHz on the dial.  At 17.9 MHz, adjust front end coil l.  Repeat these adjustment until no further improvement is possible.

The following is a translation of the alignment instructions on the second page (d_nordmende_1962_othello_stereo_abgl2.pdf). 

Alignment instructions for FM IF

1.  Attach the signal lead of a signal generator to the glass nib (evacuation cap) of the ECC85 [I'm not positive if I've translated this correctly...].  Attach the ground lead of the signal generator to the shield of the ECC85.  Connect an output meter to pins 1 and 2 of socket (15) or (16). 

2.  Detune circuits 6 and 2.

3.  Set the signal generator to output an FM-modulated signal at 10.7 MHz and adjust for maximum signal in the following order:  Circuits 3, 4, 1, 5, 2, and 6.

4.  Set the signal generator to output an AM-modulated signal at 10.7 MHz and fine tune circuit 6 for minimum output.  When doing so, make sure that the voltage across the electrolytic capacitor in the ratio detector circuitry stays below 2.5 volts.  This should be measured with a high impedance (> 10 kohm) DC voltmeter.

The following is a translation of the alignment instructions on the second page (d_nordmende_1962_othello_stereo_seil.pdf).

Alignment instructions for FM front end

Turn the tuning capacitor so that the plates are fully meshed.  Adjust the FM dial pointer so that it lines up with the end mark on the dial.  Connect a 240 ohm output impedance signal generator to the antenna input.

1.  Setting the frequency range:  With the tuning capacitor plates fully meshed, set the signal generator to 86.7 MHz and adjust oscillator coil D for maximum signal.  Then set the signal generator to 100.5 MHz, and with the tuning capacitor plates fully unmeshed, adjust oscillator trimmer C for maximum signal.

2.  Coupling circuit alignment:  Adjust RF coil G at 88 MHz and RF trimmer F at 98 MHz for maximum signal.  Repeat these adjustments until no further improvement is possible.

3.  Check of oscillator amplitude:  The oscillator amplitude should be between 2 and 4 volts over the entire tuning range.

4.  Point H is useful for adjustment of the neutralization of the RF front end stage.  Should adjustment of the neutralization be necessary, it is necessary to remove the B+ from the RF front end stage (R 59) before adjustment.

5.  The correct adjustment of the neutralization trimmer E is needed to minimize radiation of interference signals from the receiver.  Adjustment takes place at the factory to minimize radiation.  Further adjustment should generally not be attempted.

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Good luck with your alignment!

Best regards,

Tom

To thank the Author because you find the post helpful or well done.

Many thanks for your  help

I hope that way make the correct alignment.

Best Rgards

Hernani

To thank the Author because you find the post helpful or well done.