Rohde&Schwarz, EK07D Restauration

Grundlagen und Selbstbauprojekte, Restaurationen - basics and homebrew radio projects, restorations
ARCHIV
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Re: Rohde&Schwarz, EK07D Restauration

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Wout hat geschrieben: Good Morning Wolfgang,

Thank you for your reply on my posting!
Well, speaking German might work for me, writing is too much of a challenge... I am Dutch.

I did check the 2 manuals I have and both are indicating the DC voltages + current. No AC voltages there except for the dial lights and filaments of the tubes (or should I say valves).
I would be specifically interested in the AC voltages from the transformer which are feeding the rectifiers. This might help to fix the transformer specs.
The other part is to check the current draw from both the filament windings - but this is something I can carry out myself with an external transformer.

No rush, I have a day time job and not always that much time for the hobby unfortunately!

Thank you in advance,

Kindest Regards,
Wout
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ARCHIV
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Re: Rohde&Schwarz, EK07D Restauration

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Wout hat geschrieben: Morning Martin!

I did find the plug (DIN 41622) and ordered 2pcs. I expect them to arrive somewhere end of next week.

Thank you very much in advance for the work on the measurements! I am still not sure whether I will just copy the original PSU design OR I make a more 'modern' version with a couple of chip-based voltage regulators.... Perhaps it's nicer to keep it as close to the original as possible...

Will let you know when made up my mind. The choke sounds good to me!

Kind Regards,
Wout
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Re: Rohde&Schwarz, EK07D Restauration

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AZ12 hat geschrieben: Getting a NEW Transformer is a little bit senseless...

You can plan 150-250 Euro for such a big,complex Transformer.
For a rotten or defective but complete EK07 at eBay usually around 100 E.

Greetings,
Jens
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ARCHIV
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Re: Rohde&Schwarz, EK07D Restauration

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Wout hat geschrieben: Hello Jens,

You are probably very right. This is why I am carefully considering what to do.... a new transformer... or build something with multiple, less costly standard transformers. Obtaining a defunct EK07 seems also not that easy. Let's see, I still need to make up my mind.

Kindest,
Wout
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ARCHIV
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Re: Rohde&Schwarz, EK07D Restauration

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wolfgang1950 hat geschrieben: Good morning Wout,

I doublechecked my documentation, as you already stated, the is no information about detailed data of the transformer, just DC voltages and currents an some AC voltages without currents.

That leaves you with 3 options:

1. Measuring or calculating of the needed voltages and currents and
a: Order a custom produced new one. It's not that complex, I don't know whether it will cost € 150 to 200.
b: As you mentioned, supplying the needed voltages by off-the-shelf transformers.

2. As Jens mentioned, buying a completely damaged and unrepairable receiver and cannibalising the transformer. That is however not the preferred method in this forum.


Kind regards

Wolfgang
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Re: Rohde&Schwarz, EK07D Restauration

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Wout hat geschrieben: Hello Wolfgang,

Thank you very much for double checking in the manual.

I have a rather hefty low-voltage transformer and a variable auto-transformer here and when I am receiving the PSU connector in the mail I will start measuring the filament currents.

Keep you all posted,

Greetings from Holland,
Wout
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ARCHIV
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Re: Rohde&Schwarz, EK07D Restauration

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wolfgang1950 hat geschrieben: Good afternoon,
I did some collection of information from the schematics and did some calculation. The transformer has the windings:

Anschluss Wicklung Seite Spannung Strom/comment
1 – 6 W 1 Primär 220 V
7, 8 W 2 Sekundär 5,8 V 3 Skalenlampen
9, 10 W 3 Sekundär 24 V Gleichsp 80 mA
11, 12 W 4 Sekundär 0,115 A Schleifenstrom
13, 14 W 5 Sekundär 220V Gleichsp 0,21 A
16, 17 W 6 Sekundär 85 V Gleichsp Stabilisiert 2,3 mA
17, 19 W 6a Sekundär Zusatzwicklung für W7
16, 19 W 7 Sekundär 150 V Gleichsp stabilisiert 1,72 mA
21, 22 W 8 Sekundär 6,5 V Heizung HF-Teil, Steueroszillator, Eichoszillator
23, 24 W 9 Sekundär 6,2 V Heizung Regel-, ZF-, Steuer-Teil, Selektivfilter

Calculating a little bit around, I get


Anschluss Wicklung Seite Spannung Strom Leistung
1 – 6 W 1 Primär 235 V 0,5 A 105 W(summarised)
7, 8 W 2 Sekundär 5,8 V 0,6 A 3,5 W
9, 10 W 3 Sekundär 17 V 0,1 A 1,7 W
11, 12 W 4 Sekundär 3 V 0,15 A 0,45 W
13, 14 W 5 Sekundär 165 V 0,25 A 41,3 W
16, 17 W 6 Sekundär 299 V 10 (30) mA 3,0 W
17,19 W 6a Sekundär 167 V 20 mA
16, 19 W 7 Sekundär 466 V 20 mA 9,3 W
21, 22 W 8 Sekundär 6,5 V 1,8 A 11,7 W
23, 24 W 9 Sekundär 6,2 V 5,1 A 31,6 W

How the hack can I produce a table??? Hope it's readable.

it would be interesting, what values Martin find measuring.....

Kind regards



Wolfgang
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Re: Rohde&Schwarz, EK07D Restauration

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Martin hat geschrieben: I will get the radio and put it on the table.

Wolfgang, I am pretty shure an EK07 will not use 466Volt anywhere.

greets
Martin
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Re: Rohde&Schwarz, EK07D Restauration

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wolfgang1950 hat geschrieben: Martin, I agree, but it's simple math.

Step by step:

1. Required DC 150 V stabilised with 150C2. Rectification half wave by simple diode

Formula for stabilisers: Rv = (Ub-Uv)/(Iv+Ir) or transposed Ub= (Rv*(iv+Ir))+Uv

Rv = Shunt
Ub = Input voltage
Uv = stabilised voltage
Iv = required current
Ir = no signal current


For 150C2 = OA2 is I = 5…30 mA. setting Ir = 18,3 mA, Iv= 1,72 mA Iv + Ir = 20mA, RV is 3 kOhm given by manual Ub= (3000*(0,02))+150=60+150 = 210 V.

For halve wave rectification (as it is) is Uac = Udc*2,22 so Uac = 210*2,22 =466,2 V

Where's the error?

Looking closely to the schematic, there should be 2 windings:
Pin 16-17 for 85 V stabilised and
Pin 16-19 for 150 Volt.
So probably there is a second winding from pin 17-19 in serie to the one 16-17 meaning

winding 16-17 299 V for 85 V
winding 17-19 167 V both in serie giving the 466 V

Have a nice evening

Wolfgang
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ARCHIV
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Re: Rohde&Schwarz, EK07D Restauration

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Wout hat geschrieben: Good evening Martin & Wolfgang!

Wolfgang, apart from the other calculation model you are stating, where is the 2,22 coming from?

Wout
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