This is a summary of my experience buying russian tubes on Ebay.

When I decided to build another amplifier, I surveyed the market place. It appear that there were some decent deals on Ebay for 4CX800/GU74 tubes. Several sellers offered them. Each seller's feedback was examined and I started bidding on tubes offered by the ones that had acceptable feedback.

A GU74 was won on an auction by "exland". The transaction went smoothly so I bid on another. Because of the long shipping times involved, by the time I had a socket and was able to test the first tubes received from "exland", there were a total of seven assorted new and used GU74's in the pipeline.

It is well publicized that one needs to pre-condition these tubes before applying full voltages to them. I set up a "tube tester" on my bench and proceeded to do this.

The filament of the tube under test was ramped up using either resistors in series with the primary of the filamnet transformer or a variac while watching the filament current with a clamp-on ammeter. After the filament was hot, an ohmmeter was used to check for grid operation by observing the resistance in both the forward and reverse bias conditions. After several hours of filament operation, low voltages were applied to the screen and anode from a current limited supply. With a variable negative grid supply, a simple grid voltage / anode current curve was measured. Screen current and anode current were both monitored during this process.

The first tube conditioned/tested was advertised by "exland" as NEW. When first received, it rattled when shook indicating loose material inside the tube. It failed the grid resistance test indicating a grid to cathode short. Turning the tube upside down and tapping the anode cooler would temporarily clear the short. The tube was conditioned for two days with only the filament running and tried again. The short had returned and was cleared again by tapping the cooler. Running a grid-anode curve showed that the tube drew much higher anode current for a given grid voltage than the maunfacturers data sheet specified. In fact my adjustable grid bias supply did not have sufficient range to achieve cutoff. This tube probably has internal damage and is unuseable.

The second was advertised by "exland" as USED. This tube also rattled when recieved. The short was also cleared when inverted and tapped. The tube was pre-conditioned as above after the short was temporarily cleared and tested. It had high current like the first tube and would still short after a period of operation. This tube is unuseable.

The third tube was advertised by "exland" as NEW. It also rattled when received and was cleared by tapping. After pre-conditioning, the tube drew somewhat more anode current than it should and would short after a period of operation. This tube may be able to be used if the short does not come back, but I doubt it.

The fourth tube was advertised by "exland" as USED. It did not rattle and passed all tests after pre-conditioning.

The fifth tube received was an "exland" NEW tube. It passed all tests after pre-conditioning.

The sixth tube was an "exland" USED tube. It also passed all tests but had marginally high anode current.

The seventh and last tube received was an "exland" Used tube. When the filament voltage was ramped up, the current was 30% higher than manufactureres specification. The tube did not pass the grid resistance test and appeard to be open circuit. When voltage was applied to the screen and anode, no current was indicated. It appears this tube has internal mechanical damage involving the cathode and filament. This tube is unuseable.

At no time during the conditioning process was voltage applied to the anodes in excess of 800 volts. This precluded the possibility of my damaging the tubes due to a "flash-over" caused by residual gas. When the anode current data was recorded as high, the tube filament was run for several days to allow the getter to do a better job of removing gas. In no case was there any change in the grid voltage /anode current observed after this extended conditioning.

The shipping times varied from 3.5 weeks to 9 weeks. This made it very difficult to take any action on the DOA's When confronted with the results, "exland" implied I damaged the tubes and stopped communicating. To sum up, 7 tubes won at auction, three NEW and four USED. Of those I have one NEW and two USED tubes that *may* be useable in an amplifier.

I recommend that potential buyers be very cautious when dealing with "exland".

This problem is not limited to "exland" I won two GS35B's on auctions run by "Anthony Welsh". One of those was DOA. After paying a very high cost to return the tube to him at his request, I still have not seen a refund or replacement. I think I'm screwed again!

My position now is that all non-US sources of tubes are not to be trusted any father than you can see them. I will not buy from any of them again.

Larry - W7IUV