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Author Topic: Grundig Satallit 750 SW tuning anomaly...  (Read 206 times)

KK4GMU

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Grundig Satallit 750 SW tuning anomaly...
« on: November 26, 2021, 12:14:41 PM »

Currently I'm experiencing a tuning anomaly. When I turn the main tuning knob around any SW band, the noise floor increases when the knob is near 8 o'clock and diminishes when the knob is near 2 o'clock, irrespective of the frequency. I'd say the difference in noise level is at least 2 or 3 S units from one extreme to the other.

Any thoughts about what is causing this?
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IC-7100, RSPdx, AT-D878UVII-Plus HT, TGIF Spot

KC6RCM

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Re: Grundig Satallit 750 SW tuning anomaly...
« Reply #1 on: November 26, 2021, 12:39:46 PM »

Receiver location?  Replacing the tuning encoder is an experimental option...
https://www.anon-co.com/product/tecsun-s2000-tuning-encoder
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KK4GMU

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Re: Grundig Satallit 750 SW tuning anomaly...
« Reply #2 on: November 26, 2021, 01:16:53 PM »

Receiver location?  Replacing the tuning encoder is an experimental option...
https://www.anon-co.com/product/tecsun-s2000-tuning-encoder

Thanks.  Only a bit more $ than the volume pot I replaced 4 years ago.

By "experimental option" do you mean a new encoder may or may not solve the problem? Like 50/50, 80/20, or 20/80?

Receiver location: On top of  a 26" tall bookcase adjacent to north facing windows in North Central Florida.  What does "location" have to do with the odd behavior of the tuning knob?

Is this (potentially) defective "tuning encoder" a common problem on the 750, like the poor life span of the volume control that was a well-known and widespread problem?

What is the level of difficulty in replacing the encoder compared to replacing the volume control?

This type of (recurring) problem makes me appreciate the SDR I recently installed as well as the Sangean ATS909X2 I just ordered.

I'm guessing Grundig China got a bargain price on many of the components used in the 750.
« Last Edit: November 26, 2021, 01:32:46 PM by KK4GMU »
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KC6RCM

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Re: Grundig Satallit 750 SW tuning anomaly...
« Reply #3 on: November 26, 2021, 02:14:15 PM »

I'd try the encoder replacement, especially if it has the notorious knob wobble.  I'd say it's a 50/50 chance on the repair.  I would have moved the radio to an outside location, in case it was near RFI generating equipment...  Just to confirm.

The Grundig Satellit 750 was made by Tecsun and is now the Tecsun S2000.
https://www.qsl.net/n9ewo/s750.html#:~:text=The%20Grundig%20Satellit%20750%20%28as%20it%27s%20known%20in,it%27s%20known%20as%20the%20eton%20"Satellit%20750"..%20%28whew%29.

Look for tutorials on YouTube and other forums regarding encoder replacement.  Good luck.
https://herculodge.typepad.com/herculodge/2010/06/rich-suggests-ways-to-improve-your-grundig-satellit-750.html


« Last Edit: November 26, 2021, 02:17:53 PM by KC6RCM »
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GRUMPY2021

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Re: Grundig Satallit 750 SW tuning anomaly...
« Reply #4 on: November 26, 2021, 02:21:14 PM »

" may or may not solve the problem? Like 50/50, 80/20, or 20/80?"     I would say 47.6/52.4     smh

Deoxit first.
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W8RMV

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Re: Grundig Satallit 750 SW tuning anomaly...
« Reply #5 on: November 26, 2021, 03:28:57 PM »

I agree with Grumpy. 
Disassembly the encoder, or just drill a small hole in it & give it a spray of Deoxit or contact cleaner.
-Bob
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KB5ZSM

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Re: Grundig Satallit 750 SW tuning anomaly...
« Reply #6 on: November 26, 2021, 11:05:33 PM »

Before spraying all kinds of junk in it, try giving it a blast of air... cleanout the dust. Has worked on several encoders for me. I prefer to use less invasive methods first.

Good Luck,
Win
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W9IQ

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Re: Grundig Satallit 750 SW tuning anomaly...
« Reply #7 on: November 27, 2021, 04:55:00 AM »

Most encoders are optical devices. I agree with Win's thought of trying a gentle blast of clean air before getting more aggressive and potentially further degrading the device.

- Glenn W9IQ
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- Glenn W9IQ

God runs electromagnetics on Monday, Wednesday and Friday by the wave theory and the devil runs it on Tuesday, Thursday and Saturday by the Quantum theory.

KK4GMU

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Re: Grundig Satallit 750 SW tuning anomaly...
« Reply #8 on: November 28, 2021, 07:41:50 AM »

Is the problem I noted in the OP common to many makes and models of radios using similar decoders, or does this Grundig/etc. have a greater propensity for this problem, like the notorious volume pot?

I'm liking my SDR. The worst mechanical thing to fix will be the mouse wheel. 8)
« Last Edit: November 28, 2021, 07:49:47 AM by KK4GMU »
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KK4GMU

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Re: Grundig Satallit 750 SW tuning anomaly...
« Reply #9 on: November 28, 2021, 08:30:37 AM »

I'd try the encoder replacement, especially if it has the notorious knob wobble.  I'd say it's a 50/50 chance on the repair.  I would have moved the radio to an outside location, in case it was near RFI generating equipment...  Just to confirm.

The Grundig Satellit 750 was made by Tecsun and is now the Tecsun S2000.
https://www.qsl.net/n9ewo/s750.html#:~:text=The%20Grundig%20Satellit%20750%20%28as%20it%27s%20known%20in,it%27s%20known%20as%20the%20eton%20"Satellit%20750"..%20%28whew%29.

Look for tutorials on YouTube and other forums regarding encoder replacement.  Good luck.
https://herculodge.typepad.com/herculodge/2010/06/rich-suggests-ways-to-improve-your-grundig-satellit-750.html

Thanks for the repair link, KC6RMC. https://herculodge.typepad.com/herculodge/2010/06/rich-suggests-ways-to-improve-your-grundig-satellit-750.html 

I will pass on that repair. That link convinced me I would be over my head with that fix.  The volume pot was definitely an easier fix, and I "nearly" screwed that one up.

And as for "drilling a hole" to squirt in air or deoxit, I don't know exactly where to drill.  So that is off the table until I learned more about that.

I'm generally happy with the performance of Grundig otherwise.  If I attempt those fixes there is too much of a chance I would screw something up beyond cost/effective repair.  I am not as expert fixing radios as others on this site.

I will keep the Grundig as a backup and comparative radio as is. I recently installed an RSPdx/Uno and recently ordered a new Sangean ATS-909X2. https://www.qsl.net/n9ewo/ats909x2.html  and  https://swling.com/blog/2021/04/daves-review-of-the-sangean-ats-909x2/

It'll be entertaining enough for me to compare the performance of these three radios.

Thanks to all for your input into IDing my tuner anomaly.
« Last Edit: November 28, 2021, 08:39:49 AM by KK4GMU »
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KD7RDZI2

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Re: Grundig Satallit 750 SW tuning anomaly...
« Reply #10 on: December 07, 2021, 12:45:35 AM »

Most encoders are optical devices. I agree with Win's thought of trying a gentle blast of clean air before getting more aggressive and potentially further degrading the device.

- Glenn W9IQ
I had sprayed isopropyl alcohol (which is 100% highly flammable alcohol and should leave no residue) to clean the encoder of an ATS909 years ago and magically became better than new. ;D
« Last Edit: December 07, 2021, 12:47:46 AM by KD7RDZI2 »
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