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Old 26th Nov 2022, 11:10 pm   #1
andreantunes
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Default Some help with Grundig Satellit 2400

Hi all!
I was venturing in aligning my Grundig Satellit 2400. Everything is going well but I came across something weird on the aerial circuit for the 20m band (13,7Mhz to 18.200Mhz).
It seems the adjustable inductor and variable capacitor have no effect. I looked the other way and there is a bypass in the circuit with a capacitor. Can anyone help me figuring out why this component is there?
Thank you

Andre Antunes
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Old 26th Nov 2022, 11:24 pm   #2
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Default Re: Some help with Grundig Satellit 2400

Also, the original solder track to where that capacitor leads is cut off. Someone must have done this many years ago or in the factory.
The 20meter band (K4 in this case) is actually the band where I have the worst reception.
I desoldered that capacitor and resumed the broken solder path with a shunt and still nothing happens if I touch the inductor or capacitor.
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Old 26th Nov 2022, 11:25 pm   #3
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Default Re: Some help with Grundig Satellit 2400

Can you put a photo of the relevant part of the circuit diagram up please?
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Old 26th Nov 2022, 11:35 pm   #4
andreantunes
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Default Re: Some help with Grundig Satellit 2400

You can download it from here. I translated it from german to english.
https://meocloud.pt/link/b4f2e958-88...0EN_Final.pdf/
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Old 26th Nov 2022, 11:38 pm   #5
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Default Re: Some help with Grundig Satellit 2400

This is the relevant part. Not sure if resolution is OK.
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Old 27th Nov 2022, 10:46 am   #6
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Default Re: Some help with Grundig Satellit 2400

Here is the full schematic in high resolution.
Thank you for your help
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Old 27th Nov 2022, 10:50 am   #7
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Default Re: Some help with Grundig Satellit 2400

Also, another page with the components and solder side of that specific part
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Old 27th Nov 2022, 12:00 pm   #8
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Default Re: Some help with Grundig Satellit 2400

On the schematic it would help if you mark with an X where the track was cut and also show where in circuit the capacitor is connected.

Are all the relevant switch contacts for the K4 band making ok?

Lawrence.
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Old 27th Nov 2022, 1:11 pm   #9
andreantunes
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Default Re: Some help with Grundig Satellit 2400

I believe all the contacts for K4 band switch are OK. I already tried to give a good clean on the switch but it's sealed. Here you go with marks where the circuit is interrupted and the new capacitor was installed.
File is zippd for better resolution.
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Old 27th Nov 2022, 2:19 pm   #10
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Default Re: Some help with Grundig Satellit 2400

So far as I can make out, the capacitor in question is connected in series with the telescopic/external antenna circuit on shortwave bands K2 through to K6.

Lawrence.

Last edited by ms660; 27th Nov 2022 at 2:41 pm. Reason: extra info
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Old 27th Nov 2022, 2:40 pm   #11
andreantunes
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Default Re: Some help with Grundig Satellit 2400

Quote:
Originally Posted by ms660 View Post
So far as I can make out, the capacitor in question is connected in series with the external antenna circuit on shortwave bands K2 through to K6.

Lawrence.
Hi Lawrence! Would you say it's bypassing all the tuning of the aerial circuit from K2 to K6?
Thank you
Andre
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Old 27th Nov 2022, 2:47 pm   #12
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Default Re: Some help with Grundig Satellit 2400

Quote:
Originally Posted by andreantunes View Post
Hi Lawrence! Would you say it's bypassing all the tuning of the aerial circuit from K2 to K6?
Thank you
Andre
No, so far as I can make out it's just in series between the Telescopic/external antenna circuit and the tuned RF circuit circuit.

To see it on the schematic, remove the horizontal connection that goes between switch contacts E14 and E23 and replace it with a capacitor symbol.

Lawrence.

Last edited by ms660; 27th Nov 2022 at 3:06 pm. Reason: extra info
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Old 27th Nov 2022, 2:50 pm   #13
andreantunes
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Default Re: Some help with Grundig Satellit 2400

This seems to affect only K4. If I rotate the adjustable inductors and capacitors for the other bands hat has an effect. Only in K4 it doesn't do anything if I play the adjustable inductrs and capacitors L203 and C209
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Old 27th Nov 2022, 3:19 pm   #14
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Default Re: Some help with Grundig Satellit 2400

It's in circuit on the K4 band, the telescopic/external antenna is in circuit for bands K2 through to K6 when selected for AM.

Lawrence.
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Old 14th Dec 2022, 10:19 pm   #15
andreantunes
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Default Re: Some help with Grundig Satellit 2400

Hi friends, the above problem is now gone. I managed to rebuild the circuit by replacing all the components (caps, trimmer and adjustable inductor) from an old Satellit 2400 that I keep for spares. So, basically I have been solving all the radio's problems one by one.

And now I'm getting to one of the most annoying of all as I can't figure out what it is.
On the LW,MW and K1 bands I get crazy noises particularly on the K1 band. But the noise is not what bothers me more. What really bothers me is that I can get no reception on any of these 3 bands. If I use a generator with 1Khz tone acting as a local station I can hear it.
I have already replaced the internal ferrite antenna by the one on the other radio. Noise has lowered on MW and LW but no reception. I am posting a video below so you guys can see and listen.
https://youtu.be/BdJciJ_4c-Q
I have tried with batteries to make sure it's not a power supply interference. Problem persists.
I have replaced 1st transistor T401 in the circuit and also tried replacing the IC401. Problem persists.
I have also cleaned really well all the switched and such.

A full service manual with schematics, translated to english by me (an attempt...) can be found here.
https://meocloud.pt/link/63c9bc15-ee...nual%20EN.pdf/

Any help would be highly appreciated!

Thanks again
Andre
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Old 14th Dec 2022, 11:09 pm   #16
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Default Re: Some help with Grundig Satellit 2400

I have already replaced the internal ferrite antenna by the one on the other radio. Noise has lowered on MW and LW but no reception. I am posting a video below so you guys can see and listen.
Can you reverse your work and swap it back to see if that is the cause of the problem?
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Old 15th Dec 2022, 10:03 am   #17
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Default Re: Some help with Grundig Satellit 2400

Also if you have replaced the ferrite antenna, then double check and triple check all the connections. If one was accidentally reversed then you would get no reception but would it would pick up your signal generator, as the set would work but with very low gain.
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Old 15th Dec 2022, 1:16 pm   #18
andreantunes
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Default Re: Some help with Grundig Satellit 2400

Quote:
Originally Posted by agardiner View Post
Also if you have replaced the ferrite antenna, then double check and triple check all the connections. If one was accidentally reversed then you would get no reception but would it would pick up your signal generator, as the set would work but with very low gain.
I think the problem may be elsewhere because reception with the telescopic antenna is also VERY POOR. SW bands from K2-K6 and FM with external antenna works very well now. Problem is in the lower bands, LW, MW and K1.

Thanks
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Old 15th Dec 2022, 5:13 pm   #19
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Default Re: Some help with Grundig Satellit 2400

Yes, but these do require the ferrite antenna as part of the aerial circuit, regardless of the telescopic.
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Old 15th Dec 2022, 5:15 pm   #20
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Default Re: Some help with Grundig Satellit 2400

The fact that K2 - K6 (and FM) are working, proves the AM band circuitry is working, so this does point the problem at the various tuning coils along with any associated caps.
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