OK EICO Tube Tester Jockeys.....

After exhaustive restoration, re-wiring and recalibration of my EICO 667 Tube Tester, I've come up with a spreadsheet of settings that I have confidence in. They are freely available to anyone that wants to email me!

I've participated in many forum conversations on the TDPRI, FDP, Gear Page and the Antique Radio Forum (where they have a whole section dedicated to Test Equipment). I have studied many tube charts and aligned them with the tube manufacturer data sheets and pinout charts.

One of the most intriguing questions that led to my deeper understanding of the inner workings of the tester had to do with why EICO often lists two lines of tester settings for twin triode tubes. I can see why you'd want two settings if you have dissimilar halves, like a pentode / triode. However, twin triodes should share the same settings, right?!

Anyway, I think other experienced tube testers have also adopted single line settings for twin triode type preamp tubes.... The other thing that really opened the doors of perception was inserting a couple of test points so I could monitor PLATE CURRENT when pulling the MERIT SWITCH LEVER. I could then design my settings to approximate the design center values for plate current, making the settings closer to "real world" conditions in tube amps.

All the things I've learned, I've amassed into a couple documents. One is the actual tube setting spreadsheet which has separate tabs for each tube class (9-pin preamp, Octal Preamp, Octal Power, Rectifiers). The other is a heavily edited revamp of Mike Day's original EICO Restoration paper.

Thanks to Ron Reeland, Mike Cassidy and David Drake for some early information that led to my greater understanding of the nature of tube testing.....

If you want the settings and other info please feel free to email me.

eugenedunn you have a PM

Hi folks, I still get messages from time to time regarding my documents for the EICO 667 (and it's evil twin brother, the 666).

As I have said before...please email me directly at my private email....it's much easier for me to send documents and photos in private email, rather than via the forum. You can click on my profile and find my email easily, I believe.

Best wishes in all your projects folks!
Geno

Thankfully my Hickok 752A didnt have that problem but I did get it before fleabay and audiofool became popular terms.

Carl

On a 12 volt dual triode that can be operated on 6.3 volts and 12.6 volts, why would you presume
the both heaters have the same resistance after years of service life ?

That said, you could test them with 6.3 volts on each section at a time, and then compare
with testing each section of the tube, with both heaters in series.

Everyone has seen the heater bright flash momentarily as some high-end ECC tubes fire up.

What does that do to one or both heaters' resistance on 6 or 12 volt connections ?

If the heater resistances became unequal, what effect would using such a tube in
equipment using the 6.3 volt connection, i.e. VTVM's ?

Some tubes are spec'd for constant current.

A few years ago a Heathkit TT1 sold on Ebay where the seller had installed dual-bananas on the panel, connected across a precision power resistor 1.000 Ohm (0.1 percent), 5W (a 1 percent, 1.00 Ohm power resistor should also work). The resistor was spliced into the tester's plate current, switch wire. The one Ohm was not enough resistance to significantly affect tube-test readings in the TT1. Any hiZ input DCmv readout digital or analog meter (he included a cheap $5 digital DCmv panel meter in that auction) read the DC component of plate current directly in milliamps, which is the reason for using a one Ohm resistor. By doing this, it wasn't necessary to short/jumper the two bananas when not being connected to a meter, or worry about access height clearance. Why couldn't this be done on the Eico 667's (and its "evil cousin" model 666, and its predecessor Simpson model 1000)? This may solve the problem that Mike C mentioned on 18Mar2010, having to jumper the jacks when a DCma meter is not in place. I have not yet tried this mod on my TT1, E667's, 666, and Simpson 1000 due to lack of time. The remaining issue would then be what Lou, Mike and Eugene discussed on 21Mar2010 with how the DC (mv or ma, depending if one uses the 1.00 Ohm resistor in the plate current line) meter reads the rectified DC signal vs plate current values found in the handbooks.

Probably some conductive impurity in one of the mica spacers.