Hello all,
my B&K 606 tube tester reads too low with all tubes I tried. For example an old unused 6SN7GT reads 2000/2100 micromhos on my I-177B tube tester, well into the 'good' field. On my Jackson 648 it reads about 110% for each section. On the B&K 606 that same tube reads only about 80%, both sections.

The meter is ok, full scale at 1mA. I double-checked all switches and they are ok. The problem is not related to a specific socket or tube type. They all read low. Unfortunately I only got the tube chart with the tester. If someone has the schematics or calibration instructions I would love to get a copy.

Thanks,
Wilhelm F. Schroeder

Paderborn, Germany

You realize that the 606 is an emission tester, and that its readings can't be compared directly to those of another model. Also, the 6SN7 gets a poor Gm test on the I-177: because of the socket switching, section number two can only be tested with zero grid bias.
The Jackson also tests emission.

You can put a milliammeter in series with the plate, and see what the current is. There's no guarantee that the B&K and the Jackson apply the same plate voltage however.

Yes, I realize that the 606 is an emission tester. I bought your book and read it cover to cover the first evening. Absolutely brilliant! This is one of the greatest books I bought in years and I refer to it again and again. The only problem is that once you know the facts you don't trust *any* tube tester :-)

I mentioned the result from the I-177 and Jackson only to make it clear that the tube is fine.

The point is: if the 606 consistently reads around 80% instead of 100% for different types of known good tubes then there must be something wrong with it. That's why I am looking for schematics and the procedure to check/set calibration. Do you have a 606 in your collection?

Wilhelm

Yes, if it reads 80% for all tubes, there's something wrong , but you'd have to try a number of different tube types to be sure. Each tester is a little different, on what it considers "good." I don't have any of the B&K emission models, so have no experience with them. For some reason, they're not easy to find.

: Hello all,
: my B&K 606 tube tester reads too low with all tubes I tried. For example an old unused 6SN7GT reads 2000/2100 micromhos on my I-177B tube tester, well into the 'good' field. On my Jackson 648 it reads about 110% for each section. On the B&K 606 that same tube reads only about 80%, both sections.

: The meter is ok, full scale at 1mA. I double-checked all switches and they are ok. The problem is not related to a specific socket or tube type. They all read low. Unfortunately I only got the tube chart with the tester. If someone has the schematics or calibration instructions I would love to get a copy.

: Thanks,
: Wilhelm F. Schroeder

: Paderborn, Germany

I have a Lafayette emission tube tester, and the instruction manual mentions directly that the meter circuitry was designed so that no tube would ever reach full reading on the scale. The B&K may have been set up in a similar manner. My $0.02 :-)