Ffh.39d

[Val]

Does anyone know where was used 54 ohm Ffh.39d?

http://cgi.ebay.de/ws/eBayISAPI.dll?...m=330510848109

[cris2006]

I have a set myself and understand that FfH.39d was for the Fusprech.a radio that was used inside armoured cars and halftracks prefixed "Sd.Kfz". So the head band is the same as in Panzer (tank) Dfh.b headsets, and even Panzer- type rubber earpads were used, but they were not technically tank headsets. The plug in the pictures does not go with headphone switch in Fusprech.a, which required a small type plug. Actually plug to me seems replaced Czech army, not German.

Maybe someone else could add something or would have a completely different opinion?

Regards,

Cristiano

[Val]

Thanks, Cristiano,

For me that isn't just plausible that germans who went through the FU Röhren standardization road, designed just one different headphone model for one specific Fu. Such a low resistance isn't compatible with other Fu's audio output stage and in combat situation it easy to connect wrong headphones to wrong Fu. And if those headphones are the only one that survived from attack does this mean no communication at all? Interchangable and standardized radio tubes but not interchangable headphones?

Such a low resistance/impedance gives a hint that they must have been used in the line of phone communication somewhere. I believe Funksammler may know the answer.

[Funksammler]

THe Ffh.39 is not to be confused with the Dfh.d.

The Dfh.d was indeed an early Panzer low impedance headset used with early intercom systems and the Fuspr.a. The Dfh.d looks identical to the Dfh.b, but had a smaller telephone type two-prong plug.

The Ffh.39d has a different cable arrangement, the rubber cable runs over the headband to the other side, requiring only a single cable to run to the plug instead of the usual y-arrangement.

The Ffh.39d was originally fitted with rubber earpads, these are absent from the example on Ebay.

I have yet to find documentation describing the use of the Ffh.39d, but it is unlikely to be Panzer.

regards,

Funksammler

[Val]

Thanks Funksammler,

Here's Dfh.d and Dfh.g are described as headphones to the phone with appropriete plug?

http://www.techmili.com/Communicatio...Telephonie.htm

[Val]

Found this interesting thread:

http://dev.wehrmacht-awards.com/foru...=371176&page=2

And info about Dfh.d and 54 ohm headphones in general:

"Everyone else actually wore headsets with the designation “Dfh.d”, which were connected to intercom connection points, i.e. socket box units Z19 or Z20. Dfh.d headsets are easily identified by their small plugs with short stubby prongs. Externally, other than the plug and markings, they were identical to the Dfh.b, but internally they were totally different in their makeup. Because these headsets needed to serve a system that had no amplification, the resistance value is only 54 ohm whereas the Dfh.b is 2000 ohm. They are rare today, because they became obsolete in tanks when the Intercom box 20 arrived which gave the whole system a power boost that required all headsets to be upgraded to 2000 ohm, and also switched all the socket boxes to accommodate the Dfh.b plugs."

However, this doesn't make any sense to me how the amplification reason is described. Actually, the lower the impedance is, the more power you need. That's why early crystal radios without any amplification whatsoever, used high impedance (resistance) phones - 4000 ohm. So to use 54 ohm headphones you really need more power and amplification then using standard 4000 (yes, actually 4000 ohm, two 2000 ohm capsules in series) ohm headphones like Dfh.a and Dfh.b

Anyone has Z19 or Z20 box schematics? Thanks.

[Yuri D.]

I have a Z-18 box.

Yuri

[Val]

I have a Z-18 box.

Thanks, Yuri. I found your Z-18 thread:

http://dev.wehrmacht-awards.com/foru...d.php?t=448079

Could you please post bigger schematics? Thanks.

[Yuri D.]

Schamatic

[Yuri D.]

Looks like lower impedance of 675 Ohms.