Hi everybody,
As most others here I have in possession the Russian tester L3-3 - pretty nice instrument and according to most comments on www one of the best 10. Well, like you I am not really able using it because of lack of information – there is no step by step description. The rest of available translations are not accurate or even worse. Is anybody out there who is really using this instrument and could be possible making a short step by step description of getting it running?? I believe a lot of peoples would be interested. Thank you all
As most others here I have in possession the Russian tester L3-3 - pretty nice instrument and according to most comments on www one of the best 10. Well, like you I am not really able using it because of lack of information – there is no step by step description. The rest of available translations are not accurate or even worse. Is anybody out there who is really using this instrument and could be possible making a short step by step description of getting it running?? I believe a lot of peoples would be interested. Thank you all
Klemkosky has made great effort in refining some of the available translations and adding some of his own translations. I recommend downloading the zip files he has posted. I further recommend members with interest in this tester read Klemkosky's compiled translations and post their questions in this thread. We can have a systematic approach. For instance decide on reading a few pages at a time and coming back here with questions. Perhaps together with Klemkosky's help we can remove some of the ambiguities and further enhance the documentation. I believe certain words have more suitable and meaningful equivalents in English which will make the documentation far easier to read. It does take some effort and time but I am willing to share in the work if there is enough interest. Actually, using the tester is not that daunting. You have to locate the card for the tube to be tested, set the test parameters indicated on the card, and place the tester in the appropriate mode to read the anode current and Transconductance. However before anything one should be familiar with the tester itself, where the controls are, etc. how to do the initial calibration of the tester to ensure proper operation of the tester and accurate readings. This is a very well thought out and flexible instrument allowing test conditions to heart desire.
So what do you think?
In the meantime, I will try and locate to post some instructions I received from a German audiophile on the initial calibration of the tester.
Thanks Klemkosky for the excellent work. We will need your assistance if people decide to proceed with this project, at least up to the point when we would have a good understanding of the testing procedures and possibly making cards to test any tube.
Best regards
So what do you think?
In the meantime, I will try and locate to post some instructions I received from a German audiophile on the initial calibration of the tester.
Thanks Klemkosky for the excellent work. We will need your assistance if people decide to proceed with this project, at least up to the point when we would have a good understanding of the testing procedures and possibly making cards to test any tube.
Best regards
Here are some preliminary checks of some of the tester controls and partial instructions for the necessary initial calibration to ensure you will be getting accurate readings. The calibration of the oscillator is a bit more involved as you will have to set the frequency and amplitude of the signal. It is not included here however Klemkosky has done it and will be able to help. The L3-3 user manual recommends opening the two lateral doors/lids to allow for better air circulation thus allowing the tester to run cooler. You may need to adjust some controls on the lateral PCBs, so open the lateral doors on the tester. Before power-up please ensure the tester chassis and your mains input grounds are connected. This is an important safety measure not to be overlooked. What follow (already embedded Klemkosky translations) are excerpts of the instructions I received from Mr. Peter Zöllner who translated the instructions from German originally translated from Russian by Mr. Robert W. Berger. I have slightly edited the text for brevity and removed the sections on “Heater Voltage” and Transconductance “S” checks. Filament voltage controls (fine and coarse adjustments) are next to the left rotary switch.
Thanks again to Peter for his kind help.
Power up
Check grid Voltage Vg1:
Note: If grid voltage is not present, check to make sure the "MKA" switch is on "N3MEP". Otherwise grid voltage is shorted.
Calibration of microammeter/Setting zero point:
If you have finished, return "MKA" switch to "N3MEP" position!
With the above checks you should be able to obtain reliable readings of anode current of a tube under test. The transconductance calibration has not been covered in these instructions as previously noted. However, it may be read by placing the "NAPAMETPbl" switch to "S" and obtaining a reading by pressing the "N3MEPEHNE" button.
For the procedures to test a tube or additional information on the tester, please refer to Klemkosky translations.
Thanks again to Peter for his kind help.
Power up
- Allow 30 minutes for tester to stabilize
- Turn the switches "MKA" and "S" to the left "N3MEP" (measure) position
- Turn the left rotary switch to "NAP"
- Insert 4 pins in holes; 20/I (Ug2 300V), 26/I (Ua 300V), 40/II and 52/II (2x 450V)
- Press "CETb" and using "CETb" knob set your mains input to calibration mark on the meter
- Turn the right rotary switch "NAPAMETPbl" to "Ua".
- With the "N3MEPEHNE" push button pressed verify that turning Ua pot varies the applied voltage to anode by observing the meter movement
- Turn the right rotary switch "NAPAMETPbl" to "Uc2". Keeping the “N3MEPEHNE" push button pressed verify that Uc2 pot controls/varies the applied voltage to Uc2
- Turn the right rotary switch "NAPAMETPbl" to "250".
- Press the push button "N3MEPEHNE" and check that the meter points to 250V mark (125 on the meter scale). Otherwise adjust R169 labeled on the PCB in the right side of the tester. Open lid to gain access to the PCB
Check grid Voltage Vg1:
- Turn the right rotary switch "NAPAMETPbl" to "Uc1".
- To check the operation of the coarse control of -65V input grid voltage g1, put a pin into hole 1/I
- Press the push button "N3MEPEHNE". Rotate the -65 pot and verify its function by observing the meter movement
- REMOVE pin from Hole 1/I
- For -10V fine adjustment put a pin into hole 2/I.
- Press the push button "N3MEPEHNE" and verify that the negative input grid voltage fine control works
- REMOVE pin from Hole 2/I
Note: If grid voltage is not present, check to make sure the "MKA" switch is on "N3MEP". Otherwise grid voltage is shorted.
Calibration of microammeter/Setting zero point:
- Put the rotary switch "NAPAMETPbl" on "Ic1"
- The switch "MKA" must be in "N3MEP" (measure) position.
- Push the "N3MEPEHNE" button and adjust R123 ("0" MKA, to the left of the switch) with a flat head screwdriver until the meter is on zero mark. If you cannot bring the meter to zero mark, adjust R122 (YCT.0) on the mutual conductance PCB inside the L3-3 on the left hand side.
- Turn the switch to "KAJINbP" (calibration).
- Push the button "N3MEPEHNE" and adjust R125 located to the right of the switch with a screwdriver until the pointer is on the calibration mark
- You may wish to perform the above adjustments 2-3 times for higher accuracy of the micrometer
If you have finished, return "MKA" switch to "N3MEP" position!
With the above checks you should be able to obtain reliable readings of anode current of a tube under test. The transconductance calibration has not been covered in these instructions as previously noted. However, it may be read by placing the "NAPAMETPbl" switch to "S" and obtaining a reading by pressing the "N3MEPEHNE" button.
For the procedures to test a tube or additional information on the tester, please refer to Klemkosky translations.
My tester was an 86 vintage NOS. Yet I actually had to repair the 250 V supply and the oscillator before I could do a full calibration of the tester. To my surprise the culprits were leaky military grade caps! I used Wima metalized polypropylene of higher voltage rating to replace several caps including all the ones on the oscillator board. The tester has since been working very well with remarkable accuracy compared to test results from a calibrated AVO163.
One should also check the toggle switches. I had a faulty one (for measuring S) that I removed and rebuilt after cleaning the contacts. I was surprised to find that the toggle switch held together by two screws (best I remember) could actually be disassembled, cleaned and put back together. The other surprising find for me was bad tube sockets. Even though the sockets appeared to have tight grip on the tube pins, the tube pins were actually not making good contact mostly due to corrosion on the socket contacts. Visible corrosion dust all over the components can be abundant in the units that have been stored in their wooden crates for years.
I am afraid, that the L3-3 cannot deliver a sufficient heating current for 6C33C and the measurement of this tube is impossible without a hard modification of the tester.
Yes its a very good tester for the E88CC tubes.
Makes very similare results for gm as my AVO mk4 did but Ia is much much better on the L3-3
U dont have to make own card, use the 6N23P card only, just make new holes for both triods so u have all on one card..
Ur u can download card in link mentioned on some page back.
Makes very similare results for gm as my AVO mk4 did but Ia is much much better on the L3-3
U dont have to make own card, use the 6N23P card only, just make new holes for both triods so u have all on one card..
Ur u can download card in link mentioned on some page back.
Thanks Matts! I took the plunge and ordered an L3-3 off Ebay yesterday It's an unused one from 1988 in what seems to be perfect shape inside and outside. Must be one of the latest ones made I guess. I recently used the AVO MKII from a friend. AVOs are way more expensive and it's good to know you like the L3-3 even more.
I hope all is well for everyone. Has anybody tried to calibrate the test set? While repairing and calibrating a second test set, I found some errors from the original post downloads for which I apologize, a victim of cut and paste. I have attached the corrected section. There were a couple of minor typos but the major one was in paragraph 10.4.3.1.h. I had cut and pasted from the faulty manual file instead of the scrubbed file. Once again I truly apologize if it caused issue for anyone. Did not see any posts from anybody about calibration problems.
Should anyone have any questions about the calibration, please ask.
Greg
Should anyone have any questions about the calibration, please ask.
Greg
Just out of curiosity: would anyone know how humidity affects the measurements? I noticed several times that all available L3-3 manuals indicate that the relative humidity of air should be 65±15% eq. between 50-80% In winter, it's around 35% in my country. Do you take this range seriously? What parts would be effected by the humidity? The paper-in-oil caps perhaps? Can't be the vacuum (!) tubes themselves for sure.