[ARC5] WWII German Torn. E.B. Receiver Revived.

[Bob Groh]

Thank's again for another 'batch' of information on Torn E.b. receiver!  I
have one lingering downstairs in my radio room and I vacillate on whether
or not I should muck with mine. I 'inherited' mine from my uncle who, in
turn, got it from his brother who spent several years during WW II in the
European theater, A very interesting receiver.  Mine seems very complete
and in nice shape but minus the power supply case.

73
Bob Groh, WA2CKY

On Sat, Mar 23, 2024 at 8:40 PM David Stinson <arc5 at ix.netcom.com> wrote:

> This lonesome WWII German radio,
> a 1943 Telefunken Torn. E.b. regen set looked so forlorn
> sitting on the auction table between a
> Zenith Tombstone and the silver guts of a Scott
> chassis. A hole cut in the case, an abortive attempt
> to install modern tubes, savaged coil tuning slugs
> fragmented and stuck, controls frozen- this poor thing
> didn't just get "The Golden Screwdriver;"
> someone beat the helpless radio with
> the whole "Golden Toolbox," plus what
> appeared to be manufacturing errors.
>
> Introduced in 1937, it is a battery-
> powered set with two stages of TRF amplification,
> a regenerative detector and an audio output
> stage.  Audio Output Z is about 4000 Ohms.
> A matching transformer to an external speaker
> provides plenty of audio.
> The set was built in large quantities
> throughout the war.
>
> With the exceptional help of many of
> our exceptional members,it is singing again,
> needing only finish work and cosmetics.
> https://photos.app.goo.gl/DGZSWmQ8zjPJ8K1PA
> Nice introduction video by LA6NCA:
>
> https://www.youtube.com/watch?v=9t8VTuLCjds
>
> LA6NCA has an amazing collection of WWII German
> sets, including many Kriegsmarine models.
> His Torn E.b. page, detailing the recovery of
> one of the late sets, which used a zinc-cast
> front panel which crumbled:
>
> https://www.la6nca.net/tysk2/torneb/index.htm
> https://www.kriegsfunker.com/radios/torn_eb/torn_eb_1942.php
>
> If you watched the videos, you saw that the radio
> operates on eight bands, selected by a rotating drum.
> Each coil module is shaped like a slice from a
> tall birthday cake.  Each module contains three
> tuned circuits.  The third coil includes a
> tap for the regenerative feedback.
> Here is a schematic:
>
> https://photos.app.goo.gl/Vosnt9tNVjyJPBMg6
> NOTE:
> "+H" and "-H" are HEATER, 2VDC.
> "+A" and "-A" are ANODE, 90V
>
> As received, coil sets 1 through 6 had open
>   coil windings.  I found and ordered replacement
>   coils from a European gentleman.
> Replacement Coils 1, 2 and 3 also had opens
> (sold untested so that's OK; I got 4,5 and 6 back).
> I disassembled one of the bad coil sets and found
> that these lower-frequency coils were wound with
> very thin and fragile Litz wire, which has oxidized
> and opened right where it enters the winding.
>
> Aged, oxidized and fragile thin Litz wire
>   is becoming a problem with some of our old radios.
> I have several SCR-183 transmit coil sets and an
> intermittent winding in a National NC-44 IF.
> I've found a couple of NOS IF transformers with
> this problem.  The only band I'm missing which
> I wish to have working is Band 3, because
> that covers 630 Meters.  My plan is to eventually
> replace the three coils with toroid cores which
> will fit securely and still be tuneable by the
> variable caps in the circuit.
>
> If you decide to work on coils- the coil cores
> are fixed with a glue which will dissolve in
> Acetone. but sets again when that evaporates.
> If you want to tune the cores, you'll likely
> have to "re-wet" them with the acetone
> to allow them to move freely.  The coil case
> screws are locked with some kind of gray stuff
> that seems like epoxy.  It will have to be chipped
> off the screw heads and out of the screw head slot
> to get the screws off.  Be warned by my earlier
> post about using the proper screwdrivers on these
> sets or one can destroy the screws in short order.
>
> Here's an album of photos and videos.
>   https://photos.app.goo.gl/HN3fhN4RqqqZjFfA9
>
> TNX ES GL OM DE Dave AB5S
>
>
>
>
>
>
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