D is for - Kleinfunksprecher d

[Funksammler]

Although some post-war articles and books have invented a "Feldfunksprecher d" model, there never was a "d" version of the Feldfunksprecher. Instead the "d" was associated with a late war development called the "Kleinfunksprecher d". The "Dorette" as it became known was the latest in radio miniaturisation brought about by technological advances. The name "Dorette" (as in "small Dora") referred to the Torn.fu.d2 "Dora" radio, the standard portable radio set used by the infantry as the Kleinfunksprecher d operated on the same frequency band as the Torn.Fu.d2 (33.8 - 38 MHz) and could easily be integrated in existing infantry radio networks. The frequency range of he Dorette was slightly extended to partly include those of the Feldfunksprecher f (27.2 - 33.3 MHz) and the FU5 tank radio set (30.2 - 33.4 MHz) to allow infantry-tank cooperation. Thus the Dorette's frequency range was set at 32 to 38 MHz. 

 

The design of the Dorette appears to be inspired by some of the latest allied radios. The packaging and method of wearing the radio was probably inspired by the British 38 set while the use of multi-circuit valves is more typical of US designs. The use of dry cell batteries was also quite common in allied radios, but fairly unique in German radio design.

The circuitry of the Dorette roughly follows that of the Feldunksprecher h with only one of the two RL1P2 HF valves in use while receiving or transmitting. The designers added a clever trick in the receiver: after passing the HF signal from the antenna through valve three the LF signal from the oscillator/detector passes through the same valve for a second time. This so called reflex circuit essentially adds a amplifier stage without having to add an extra valve:

Note that the switch box of the microphone was not used to switch between receive and transmit, this was purely done with the main switch on the Dorette itself.

It was the use of dry cell battery technology that allowed the small size of the Dorette. The Dorette used dry cell zinc-air batteries (Luftsauerstoffbatterien). These produced a nominal 1.4 Volts per cell. The filament battery (L.S. 1.4) has its cells in parallel while the Anode battery (L.S.150 bp) had its cells in series to produce 150 Volt. The batteries were wrapped in an air tight packaging, once out of their airtight packaging, the batteries had a four week lifespan. In operation, the batteries had a lifespan of approximately 25 hours.

The Dorette was supplied in a wooden box "Transportkasten a" which held the radio, battery case, Dfh.f and Kmf.c headset, antenna and batteries in separate compartments:

The two airtight-packed batteries were stored separately and were only to be opened immediately before use:

The radio itself is a triumph of minimalistic design. The front panel contains sockets for the power supply, Dfh.f headphone and Kmf.c throat microphone. A main switch (off, receive, transmit) and the frequency tuning knob complete the panel:

The front side of the radio contains the frequency dial and the used instructions:

Note: The photograph shows the radio tuned to 32.8 MHz, which would allow it to communicate with the FU5 tank set or the Feldfunksprecher f. The higher frequencies are calibrated in the same channel numbers as the Torn.Fu.d2.

The back of the radio shows the range of the radio (2-4 km, depending on topography):

The carrying side shows the brackets used to attach the radio to the standard Y-straps of the soldier; the top clamp was clamped around the Y-strap while the bottom bracket slide behind the strap to keep the radio upright.

Note: It is interesting to note the different shades of tan used in late war production, components of this example were painted in at least three different colours.

The battery box (Batteriekasten A) contained the two Zinc-Air batteries. A leather strap allowed it to be hung on the belt of the soldier, or it could be configured as a carrying handle:

On the rear, the battery box has a bracket that allows it to be attached to the radio itself:

Note: again notice how the box is made from components finished in different shades of tan.

The dorette as a static radio station, complete with antenna, Dfh.f headset and Kmf.c throat microphone. The battery box is attached to the radio while the leather strap of the battery box is used as a carrying handle:

The Dorette uses a fairly long pliable "Bandantenne":

The correct antenna for the Dorette is 1.6 meters long and is clearly marked so on the base:

Alternatively, the radio could be worn on the chest, attached to the standard belt and y-straps  as in this impression of a late war infantryman: 

The radio is secured to the Y-straps:

The battery box is attached to the belt near where the entrenching tool is normally worn:

The Dorette was introduced in December 1944. The first production run was painted in dark grey paint. Documentation exists that proves that the first 300 or so Dorettes were shipped out in mid December. Further detective work has revealed that these radios were air-shipped into the Kurland pocket, as a number of this first batch of radios have surfaced in the Baltic. The production line had to be moved twice after it had been bombed out. The later production runs were all finished in ordnance tan.

So far, very little evidence has emerged of operational use of the Dorette on any other fronts. No period photographs have yet surfaced showing the Dorette in use. There are some hints that the hastily developed batteries curtailed the operational use of the Dorette. It is rumoured that most batteries were empty or failed soon after the radio reached the troops. The battery's required optimal temperature of +20 Celcius would also have been a problem during the winter of '44 -'45, it was recommended to wear the battery box under the overcoat during cold weather. Perhaps this is the reason why most Dorette's were found after the war languishing in stores, they were simply defective and not fit for issue.

An instruction leaflet was delivered with each boxed set detailing the basic preparations for operation:

Note: the first cartoon shows that a "Fernhörerkopfband" was delivered with the Dorette. So far no complete Dorette boxes have been found with a headband in place so it is unclear of this accessory was actually supplied. 

Another section describes the frequency band and the possible connections with other radios that could be made. 

Further sections describe how the range could be increased by pointing the antenna or using a wire antenna. The final section gives some examples of how the radio traffic should be conducted including code names:

Most surviving Dorettes today were recovered from stores after the war and were sold to companies and organisations as a cheap radio telephone. One 1950's French advertisement sells them as "Parachutist radios", starting the unfounded myth that the Dorette was created for Fallschirmjäger troops. In fact the only officially documented attribution found to date assigns the Dorette to bicycle troops.

The Dorette is one of the most common German radio types that can be found today. As usual, accessories are significantly harder to find than the radio itself. Battery box command higher prices than the radio itself and the correct antenna is virtually impossible to find. If you are very lucky, you may find a complete boxed set, some of which even contain the remains of the original batteries.

[val]

As @Funksammler already mentioned, most ground dug Kl.Fu.Spr.d's come from Baltics.

Here i add a images of ground dug early version Dorette found in Estonia.

[val]

And this relict is from Heiligenbeil Pocket.

Seems like a direct hit!

[kriegsfunker]

Here's my set

https://kriegsfunker.com/radios/dorette3.php

[val]

One of the best and most correct schematics.

[tornfuté]

Hello val 

very clean schematic, i suppose the connections for powering 

are seen from outside  the set ?

regards pierre

[val]

9 minutes ago, tornfuté said:

Hello val 

very clean schematic, i suppose the connections for powering 

are seen from outside  the set ?

regards pierre

Yes, from outside.

[val]

Dorette batteries.

https://www.radiomuseum.org/forumdata/users/15752/RADIOBOTE/Hefte/RB_2013_44_2.pdf