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Rpg4/3
Old 12-28-2017, 02:11 PM   #1
BTaylor
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Default Rpg4/3

I have machine-translated the booklet for the RPG4/3 into English. It isn't perfect, may be amusing to a fluent German speaker in spots, but has much basic information beyond what one can deduce by studying the device.
If there is any interest, I will attempt to post it for others.
Currently I am trying to repair and restore a unit damaged by shipping, which was already a little rough, over-painted exterior, no data plate, etc. No luck so far. The meter broke loose when the package was thrown/dropped. No mechanical damage to the needle. Meter glass not shattered. Not yet working.
The schematic for these seems odd compared with all the German radios. No chassis ground, or any ground for anything once line voltage reaches the transformer. Still puzzling with this. If I can't get it to function, maybe I will learn why it is trashed?
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Old 12-28-2017, 02:18 PM   #2
Yuri D.
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I am absolutely interested. Please post it. I've been using this device for every radio repair that I have done.
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RPG4/3 pdf
Old 12-28-2017, 03:28 PM   #3
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Default RPG4/3 pdf

Here is a pdf of the booklet for the RPG4/3. (If I have it attached correctly.) I think some of us will find this useful. The slightly awkward or confuting passages might be improved by a better translation, but much useful info is here. Best of luck to everyone struggling with these...
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File Type: pdf rl12p35.pdf (266.3 KB, 19 views)
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RPG4/3 pdf Booklet
Old 12-28-2017, 03:31 PM   #4
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Default RPG4/3 pdf Booklet

Lets try this again - wrong pdf first go-around!
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RPG4/3 again
Old 12-28-2017, 03:35 PM   #5
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Default RPG4/3 again

Third try. Sorry!
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File Type: pdf RPG4 3 Manual.pdf (912.1 KB, 17 views)
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Old 12-28-2017, 03:36 PM   #6
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BTaylor, can you show the images of your RPG?
It is interesting to see the damage it got.
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RPG Damage
Old 12-28-2017, 03:50 PM   #7
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Default RPG Damage

I didn't take photos of the damage. I was pretty discouraged when the shattered tube pieces dumped out. I started cleaning up and evaluating the destruction right away. The main problem was the mounting points of the Bakelite case of the test meter were not strong enough. The meter is really massive when loosened (not something you will ever want to do, I hope.) It just tore loose from the main board where everything is mounted, breaking the corners off the meter in the process. By some stroke of luck the meter glass and the needle mechanism were not broken. The tube nearest the meter was shattered.
Everything is back together, NOS tube, Bakelite repair barely detectable. Not operating yet. Was it inoperable before the shipping damage? Maybe I will figure it out. Bound to learn something, anyway!
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Old 12-28-2017, 04:09 PM   #8
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OK, then show the result so far, inside and out.
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Old 12-29-2017, 08:21 AM   #9
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Just nothing to see...
Interior and exterior look exactly like the RPG4/3 units that were never damaged. (Minus the data plate on mine.) Quite a few photos can be found on this forum and on the web.

I am in the process of replacing the 16 microfarad capacitor adjacent to the GR150 A tube. Original block capacitor had been replaced by four small capacitors, which had double their rated capacitance, and were pitched. (No, I have no photos of them.)
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Old 12-29-2017, 10:38 AM   #10
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Tell us a bit more about what happens, does the transformer hum, do the valves glow? Can you measure AC and DC voltages at the appropriate points with a multimeter?

regards,

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Old 12-29-2017, 11:03 AM   #11
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Quote:
Originally Posted by BTaylor View Post
Just nothing to see...
Interior and exterior look exactly like the RPG4/3 units that were never damaged.
...
(No, I have no photos of them.)
Little grouchy, eh? Yes, we do understand that you are not in the best mood since this thing got damaged and you haven't got it working yes. But don't lay that grouch on us.

The truth is that those things are not made any more. Although your RPG 4/3 may look like any other RPG 4/3, each one is different, has different background, has different battle scars etc. Each one is different and that's make each and every one so interesting.
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Progress? Report
Old 12-29-2017, 04:17 PM   #12
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Default Progress? Report

Basics done. Correct fuse in the voltage selector set to 125V. Transformer hums. AZ12 tube warms up. GR 150 A lights up. Both tubes are NOS. No loose wires, physical damage, or alterations apparent inside. New 16 microfarad 800+ V rated capacitor installed, with jumpers at this point. Studying the wiring diagram and covering it with additional notes.
Somewhat puzzled about checking voltages. Heater voltage to AZ12 is 4.1V AC. It seems that voltages are across transformer taps rather than to ground as is ordinary? Still at the beginning of troubleshooting, I'm afraid. In many respects the RPG is a switching device, it seems.
All available help is appreciated. I also have the diagram of the connections as seen from inside the unit. Happy to check voltages between any suggested points.
While the gauge needle swings smoothly and the zero adjustment works, I am worried that the gauge might be ruined by the shipping damage already mentioned.

By the way, the CD of test cards just arrived. Remarkable asset. Worth many times it's cost.
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Apologies
Old 12-29-2017, 04:53 PM   #13
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Val

Don't mean to be snippy. Will post some photos of my repaired RPG, but maybe not until after New Years. Both the front and rear lids had been somewhat stripped of original paint and red primered, so now they are repainted original gray. Making a stencil of "RPG4-3" for the label was too labor intensive for me, so I made a decal, which is OK by me for a repainted unit. Paint comes from a US militaria dealer in "Panzer Gray" lacquer in a spray can. Decals print on an ink jet printer. I think many labels on radios were stamped rather than stenciled, anyway.

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Old 12-30-2017, 12:26 PM   #14
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I must admit that the RPG schematics are not the clearest, but maybe this can help. First of all the schematic itself:



and secondly the plug board:



The marked voltage sockets are actually marked and can be recognised on the schematic.

For example by pinning the Anodenspannung 200 DC socket, it produces 200 Volts DC anode voltage.

You can see the contacts to which the various voltages are produced in the schematic as A2 - K - G1 - G2 - A1 on the schematic. On the plug board they are in reverse order and are actually marked A1 - Sg - G - K - A2.

To the left and right of these contacts you find another 11 sockets, these are the contacts marked I - XI in Roman numerals in the schematic. I to V are to the left, VI to XI are on the right.

The top row are the rows of contacts shown in the top of the schematic, these connect the A2 - K - G1 - G2 - A1 voltages to the correct contacts on the sockets (the actual order does not seem to bare any relationship with the order on the schematic, but for fault finding the RPG they are of no consequence...)

So for example, if you want to measure if your RPG produces the right AC anode voltage, you plug the (+) of your multimeter in to contact I and the (-) into contact VI and plug a pin into the corresponding anode voltage socket.

Unfortunately the schematic does not indicate the exact circuit diagram of the measuring instrument itself, so I am not sure if the current measuring parts uses a thermocouple element, or a shunt and rectifier (probably the latter...), but fortunately there are an number of test connections to diagnose the instrurment.

You will notice that in the schematic, the indicator instrument has a DC measuring point at contact III and an AC measuring point at contact VII. So instead of your multimeter, you can use the RPG's instrument to test the voltages produced. So if you connect a jumper between contacts VI and III and you select a DC anode voltage, your RPG instrument should indicate a voltage when the control knob is turned to position 12 or 13. (because the scale is not calibrated to 200V it will not indicate 200 or anything logic, I assume the factory had special test cards to test the calibration....) In any case, if your instrument moves, it proves that the galvanometer in the instrument is working, if not it is defective.

A similar test can be performed with an AC voltage on contact VII of the meter, this should prove if the rectifier bridge is working or not.

So have play to see if you get any results and be careful, always start with the lowest voltage possible...

regards,

Funksammler
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RPG Evalation
Old 12-30-2017, 01:42 PM   #15
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Default RPG Evalation

Funksammler -
Thanks much for the input. Currently have a house full of family guests so will postpone a return to the RPG until I can give it my full attention and correlate your advice with the actual unit. I will re-post then.
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