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I have bought a pig in a poke or maybe not? German OB38

Started by dsk, October 13, 2017, 01:30:35 PM

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dsk

 8) Sometimes it do not turn out so good.
I can not claim any, the seller stated to know nothing, he just was cleaning up after his father.


And it was not that expensive $65 and it is not lost.


Never got a phone so carefully packed, and I could fix most of it with parts I have. Maybe I had to high expectations?


The phoe is a WWii Officers desktop field telephone.
But the ringer was missing , the crank was missing (known when i bought it), and the generator was stuck.
The handset was not a field phone handset, but frome the same time, and probably used with this phone for since WWii
The receiver capsule was missing and the original 1940 transmittercapsule looks well, but does not work well.
The Generator crank and ringer you see is from a field telephone I had for spares, so it is almost as new again.


dsk


edit
adding sellers picture

dsk

My idea of posting this was to not always post happy stories, so now i may smile of it  :D
The ending is still quite happy, Now it is working, and I have learned even more.


If you read what is written about this in English it seems like the phone is possible to operate at 3 different manual systems:

       
  • Local battery     ;D Works perfect
  • Local battery with automatic ring off  >:( I can not believe a dc signal trough 1400 ohms is a safe ring off signal.
  • CB    >:( Going off hook uses the ringer as holding coil, but 1400 ohms is far to much.
Nobody has (as far as I know) published a concussion like this before.
8)  i have actually made it worse, because the ringer I put in has 2500 ohms resistance.  (I could put the 2 coils in parallel and get 625 ohms, but that will increase the ringer load)




dsk

Tried to translate the schematics. The short SB is the connection used with automatic ring off. Did not what to change that to.
The red ring around capacitor C2 is to point out where I would have soldered a strap to use it as on a CB system if needed.
That has been standard on other German phones with the same LB ind. coil. 
It will always need a transmitter battery so in that case it will be CB signalling LB talking.


I'll keep it as it is, and use it on magneto systems.


dsk  ;D

dsk

I have just been updated from another collector, his phone has a ringer with 340 ohms resistance!  That will make the functions work as described in the manuals.
My next question witch maybe never will be answered is, how great will the REN load be with a 2 microFarad capacitor in series with a 340 ohms ringer.

dsk

RB

Very nice!
Somewhere on here, someone, maybe Unbeldi, or Victor, talked about ren numbers, and assoc components with calculated load values.
Maybe they will chime in and rescue you! :D

dsk

I guess it may be pretty high. I Changed to the closest I could get, and with a ringer with parallel coils at atotal resistance of 600 ohms I measured about 3 REN (Used the method described in Ralph Meyers book) This ringer has the same visual look as the original one at 340 ohms.  I have to guess the original one had higher REN load.
When I did the same on an EE-8 with the selector in CB position and on-hook, I measured 3.3 REN.

dsk