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korting: 54W; Syntektor

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Forum » Radios and other type of sets (Physics) etc. » MODELS DISPLAYED » korting: 54W; Syntektor
           
Dennis Daly
 
 
USA  Articles: 31
Schem.: 120
Pict.: 5
28.Sep.08 16:59

Count of Thanks: 6
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Greetings Fellow Collectors!

 I am fortunate to be in the process of restoring an example of this somewhat historic and technically interesting model from the manufacturer Körting.

 After extensive routine work (cleaning, the restuffing of all paper capacitors, etc. etc.) and a complete realignment, I found the UKW to be exemplary in performance, but the LW/MW/KW bands had rather dismal performance at best.

 Knowing this model possesses a broadband (untuned) R.F. amplifier stage, I thought that its poorer than average AM performance was quite unusual, especially with the MW band.

 I proceeded to trace and investigate a cause.....Was it possibly a mistake in work by myself, or a hidden defect I had overlooked in the resto process?

 After a period of time poring over the schematic, taking passive and dynamic measurements and jotting notes,---I discovered the root cause.

A mistake in switchboard bus wiring had been made during assembly at the factory!

 A ground lead was connected to the wrong bus.  (39)

 No direct ground return was provided for bus (40)

 Apparently, these wiring errors were somewhat compensated for at the factory by (mis-) alignment and in doing so, must have allowed this particular unit to pass quality control/ testing.

 Simply moving the misplaced bus one row to the left side of the tasten Pertinax switchboard and adding the missing 1K resistor,(39 bis 39a,) together with a total realignment of the AM R.F. circuits made for a pleasing surprise of a radio that performs very well!

 Please note!

 Herr Staginnus has informed me that there are two variants of this model, as noted in the model page data list, schematics "c" and "d." (sch1, sch2) So, my example may not use the 1K cathode resistor switched into the EBF80 (1) cathode circuit for LW band only. (39-39a) I shall remove this resistor I had placed and revert back to direct bus connection per schematic "d," as I found it.

My radio did have the (40)  bus/ ground wiring error as mentioned. Sorry for any confusion, and thanks to Herr Staginnus for this observation. We learn!

 This radio is certainly worthy now of the installation of a new EM85 indicator tube!

 Of little technical use, but this is the first radio that I have literally restuffed the housings of the original Germanium diodes (discriminator) with matched, modern units (NTE110MP)

 I type this note as a hint to other owners of the model 54W in the event my radio was not the only example allowed to escape the factory of Körting with this error in bus wiring.

 Regards,

 D. Daly

This article was edited 02.Oct.08 00:23 by Dennis Daly .

Omer Suleimanagich
Omer Suleimanagich
 
USA  Articles: 428
Schem.: 3
Pict.: 56
28.Sep.08 20:14

Count of Thanks: 3
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Hi Dennis,

 

That Korting model looks great!

Just out of curiosity,  wouldn't  be easier to just place a paper scan of the original capacitors, over the new yellow caps, and color the ends with a black permanent marker?

What's your technique for restuffing these smaller paper caps?

I only restuff the big electrolytic cap around the rectifier, and place all the removed components in a bag and leave the bag in the chassis.

I figure the next person working on the radio might not realize that components were replaced.

What do you think the protocol should be for radios of this period?

 

 

Dennis Daly
 
 
USA  Articles: 31
Schem.: 120
Pict.: 5
29.Sep.08 00:11

Count of Thanks: 4
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Hello Omer,

 There are many procedures  that may be deemed "easier."

 Being "easier" may not meet the personal requirements or wishes of the individual restorer.

 The original fiber housings as found in this model under discussion are easy enough (for myself and others,) to extract the internals and install the smaller, modern replacements and reseal with a modern equivalent. The replacement caps are physically smaller, so this size difference would be a consideration for me. I don't restuff every or all paper capacitors on all  German-produced models that come across my bench.

 If I, or anyone, chooses to restuff capacitors or diode housings for a particular special model, or all radios, is simply a personal choice and not a matter of "protocol," in my opinion.

 Saving old capacitors, as is most of this conversation, just a matter of one's opinion to do so or not.

 

This article was edited 29.Sep.08 00:16 by Dennis Daly .

  
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