Something you will not see very often is the "Mikrofon und Fernhoerer Pruefgeraet a". It is a small test device that can test the main types of micropones and headsets.
They were made in a very small series, two were found in the 1980's, one remains in my father's collection and the other went to Arthur Bauer's collection.
Lid of the Pruefgeraet with date plate. Note the serial number "11":
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On the side of the box there are a number of sockets to connect the various types of headphones, handsets and micorphones:
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When opening the lid, the controls (main switch, volume control and voltmeter) of the device become visible. A plug in vibrating relay (top left) is used to generate a test signal. Operating instructions are fixed to the insde lid:
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The device runs on a 2,4 Volt NiCd battery (e.g. 2,4 NC 28).
For microphone testing, the first four positions of the main switch were used (Blue sector). It could test the cables, correct functioning of the microphone switch and the signal strength of the microphone.
For headphone testing, the last two positions of the main switch were used (Green sector). In the first position, a specific signal strength was generated, the airgap in the headphones could now be adjusted for maximum volume. In the final position, the volume is turned to full strength, in this position the headphones are tested for distorsion ("klirren").
Finally the position "Durchsprechen" allows the speech quality to be checked with both a microphone and headset connected.
In the same way the field telephone handsets can be tested. Since the speaker in the FF33 handset is not adjustable the tester was used to decide whether or not to replace the speaker and/or microphone.
Given the low number manufactured, these testers would probably have been used at higher echelon repair workshops.
enjoy,
Funksammler
They were made in a very small series, two were found in the 1980's, one remains in my father's collection and the other went to Arthur Bauer's collection.
Lid of the Pruefgeraet with date plate. Note the serial number "11":
<a href="http://s672.photobucket.com/albums/vv86/Funksammler/?action=view&current=DSC01156.jpg" target="_blank"><img src="http://i672.photobucket.com/albums/vv86/Funksammler/DSC01156.jpg" border="0" alt="Photobucket"></a>
On the side of the box there are a number of sockets to connect the various types of headphones, handsets and micorphones:
<a href="http://s672.photobucket.com/albums/vv86/Funksammler/?action=view&current=DSC01157.jpg" target="_blank"><img src="http://i672.photobucket.com/albums/vv86/Funksammler/DSC01157.jpg" border="0" alt="Photobucket"></a>
When opening the lid, the controls (main switch, volume control and voltmeter) of the device become visible. A plug in vibrating relay (top left) is used to generate a test signal. Operating instructions are fixed to the insde lid:
<a href="http://s672.photobucket.com/albums/vv86/Funksammler/?action=view&current=DSC01158.jpg" target="_blank"><img src="http://i672.photobucket.com/albums/vv86/Funksammler/DSC01158.jpg" border="0" alt="Photobucket"></a>
The device runs on a 2,4 Volt NiCd battery (e.g. 2,4 NC 28).
For microphone testing, the first four positions of the main switch were used (Blue sector). It could test the cables, correct functioning of the microphone switch and the signal strength of the microphone.
For headphone testing, the last two positions of the main switch were used (Green sector). In the first position, a specific signal strength was generated, the airgap in the headphones could now be adjusted for maximum volume. In the final position, the volume is turned to full strength, in this position the headphones are tested for distorsion ("klirren").
Finally the position "Durchsprechen" allows the speech quality to be checked with both a microphone and headset connected.
In the same way the field telephone handsets can be tested. Since the speaker in the FF33 handset is not adjustable the tester was used to decide whether or not to replace the speaker and/or microphone.
Given the low number manufactured, these testers would probably have been used at higher echelon repair workshops.
enjoy,
Funksammler
I would need one to test my equipment. Thanks for sharing.
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