RPG 3/4 (Röhren Prüfgerät 3/4) Vacuum Tube Tester
 
This vacuum tube tester was manufactured exclusively for the Wehrmacht by the Max Funke firm. Released in 1943, this tester can verify all German, American, British and Russian vacuum tubes manufactured by those countries by that year. Since radio technology remained relatively the same from 1943 to 1945, the RPG 3/4 is able to test most if not all vacuum tubes of World War II based in the European theater.
 
Specifications:
 
Principle: Tests viablilty of vacuum tubes by applying Heater and Anode voltages to tubes. Also tests other aspects of tubes by applying voltage to various pin combinations. Voltages and pinouts are configured with a punch-card system.
Power Requirements: AC voltage range switch (110 to 250 V)
Case material: Wooden and metal case
Vacuum Tubes: AZ12, GR150A
 
This is what the RPG 3/4 looked like when I first received it. The original paint is in very good condition.
This is what the RPG looks like with the lid open. To the left are the tube configuration cards, there are over 1500 of them representing all WWII German, American British and Russian tubes used up to 1943. Right above the configuration cards are the pins that are inserted through the holes in the cards into the tube configuration platform. The right side of the RPG consists of various tube sockets, the tube configuration platform, the usability meter, and the testing knob.
 
The inside of the lid has additional tube sockets. The plug at the end of the cable inserts in the red-painted receptacle in the middle of the main RPG tube socket board. This allows the lid-based sockets to be read by the usability meter.
 
Here we're testing a DF11 vacuum tube for the WR1/T entertainment radio. You can see the arrow on the card pointing to the place where the DF11 tube is inserted. Next to the tube you can see the plug for the lid sockets.
 
Here I'm testing a newly arrived shipment of 10 RV2P800 tubes. All 10 worked very well and were all in the "Gut" category.
 
Here's the RV2P800 in its testing socket.
 
Here's what the RPG 3/4 looks like inside.
 
Here are the two vacuum tubes of the RPG 3/4. On the left is the AZ12 and on the right is the GR150A (stabilitron).
 
Here is the most complex part of the RPG 3/4 - the tube testing switch. This is a complex mechanical part which we had to take apart and clean for the RPG to start working again.
 

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