saba: UKW alignment question

Hello,

I am seeking help with the UKW alignment procedures. I am from the US and cannot read German. Using an online translator is somewhat helpful but I am still unclear about the instructions for adjusting trimmers 26 through 31, (oscillator and associated trimmers). Can anyone translate instructions for these trimmers in to English?

Thank you.

Scott Rhode

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Hi Scott

I tried my best to translate it, but I'm sure it is not really english.
The instructions were a bit confusing not having the set aside, I hope it is understandable

Regards Marc

Alignment Instructions for VHF Fixture 903 U 100

1. Set pointer to starting position, adjust Pos.27 input tuning circuit core (turned out) to flush with Pos.30 oscillator bobbin with the aid of Pos.31 adjustment screw.
2. Turn Pos. 29 input tuning circuit trimmer fully in and turn Pos.26 compensation trimmer ¾ in.
   Feed 87.5 MHz, AM modulated to antenna jacks. Set dial pointer to 85° on the UKW dial. Align Pos.28 oscillator trimmer to max.
3. Radiation control by means of a μA meter (15μA) with Germanium Diode rectifier to antenna jacks. Turn Pos.26 to min at dial pointer position in the middle.
4. Repeat the alignment 1 and 2 for min. radiation in accordance to proper dial calibration
5. Align input tuning circuit with Pos.29 to max., conceivably with the aid of the tuning knob.

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Hi Marc.

Thank you for helping me. With your instructions I at least have the UKW band playing fairly well. I am struggling a bit with step 3 as I don't understand what is meant by "radiation contol" or how to connect the uA (milliamp) meter. If you can offer any further assistance I'll be grateful.  If you cannot, I am still grateful as I am way ahead of where I was before your kind assistance.

Cheers,

Scott

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Hi Scott

Short explanation for 3

The oscillator frequency may radiate over the antenna, distorting other services in the FM or in the VHF II band (DAB,earlier TV Band). Moreover there is no RF amplification stage that might attenuate this. To minimize it, the RF tank is coupled to a neutral point which needs to be aligned with the compensation trimmer Pos. 26 (imho Pos.25 in the schematic).

Connect a germanium diode (1N60) or a schottky barrier diode with low forward voltage (BAT85) in series with the μAmmeter to the antenna jacks.

Good luck, it won't be easy!

Cheers
Marc

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Hi Marc.

Thank you for your clear explanation. This procedure sounds like fun (I hope that's true).

Cheers,

Scott

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