Here is a helpful tidbit for use with your Eico 666.
The EICO 666 is the early version of the
EICO 667. As such the setup of the testers is, for the most part, exactly the same for both models. These testers have a bank of levers that setup the tube elements, voltage ranging for the grids, screens and plate, and a shunt ranging used for setting the shunt on the meter for proper reading of the current. Where you run in to differences is due to the range of tubes they are capable of testing. The Eico 666 will test tubes that have up to 8 pins where as the Eico 667 has the ability to test tubes up to 12 pins. Because of this, the number of setup levers is different. The levers on the Eico 666 are labeled thus:
1 - 9, C, V, S
While the levers on the Eico 667 are labeled thus;
1 - 12, C, V, S
The numbered levers correspond to pin numbers on the sockets. "C" is the plate cap clip. "V" set the voltages for the elements and "S" sets a shunt resistor on the meter.
Now, where this information becomes useful is for the fact that when Eico introduced the 667, they stopped production of the 666, but of course tubes were still being produced and the tube charts were continuously updated. The charts for the 667 can be used with the 666 if you know where the differences are. And it really is simple. Below is a reference example I used to help another DIYer who was having difficulty with this very issue.
Attachment:
reference.jpg
The chart sample is from the Eico 667 chart data. As you can see, the "Levers" group has 13 positions indicated. The Eico 666 only has 10. So the user, when using a Eico 667 chart for the Eico 666 is faced with the apparent dilemma of “how do I make this chart work”. It is actually very, very simple. It helps to understand how your tester works and what each lever represents. It is easy to over think and go wrong or say “I don’t know”. As you can see in the reference, I have broken down how the grouping applies to the Eico 666. Just remember, each numbered level corresponds to a pin in the socket and nothing more. So when you’re working your Eico 666 from an Eico 667 chart, you will simply ignore the lever setting for levers 10, 11, & 12.
For visual comparison:
Attachment:
Eico666.jpg
Attachment:
Eico667.jpg
I know someone is probably looking at the reference given above and comparing it to the setup of a 0A2 from the Eico 666 chart. And he is probably thinking "wait a minute, these aren't the same settings, Les must be wrong". Yeah, I noticed that too. Actually, they're both correct for both models. However, the settings presented for the 0A2 from the Eico 667 chart is more correct. The Eico 666 chart has you set filament voltage to 117v and pin 1 (lever 1) is connected at filament supply. Pin 2 (lever 2) is set at GND. Pin 4 (lever 4) is also taken to GND. The remaining pins are "open". The Eico 667 chart ignores a filament setting (actually says 0), and instead selects a higher plate drive using the "V" lever and Plate setting @ "60" (that doesn't mean 60 volts). The levers therefor connect pin 1 (lever 1) to PLATE, lever 2 to GND and all others "open". What does this represent? Over time, Eico updated their test parameters to give a more accurate result. This was apparently one of those updates.
CHEERS!!
Login
Register
FAQ
It came with a measured tube (emission test) so I will have to compare to the EICO 667. Of course the problem with that is that if they don't match ... well, I won't know which is correct or if both are wrong! 
Stay tuned... and photos to come too!
