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Old 25th Mar 2006, 1:02 am   #1
igranic
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Join Date: Jan 2005
Location: North Bedfordshire, UK.
Posts: 395
Default Taylor 45c Valve Tester - a caution -and an appeal for information sharing

There was I believing that all Taylor 45c valve testers were created equal - that is until I tried to test an ECF80 !

My "Valve Chart for use with the Taylor Valve Tester Model 45C", is an original printed book in its original binding, but it bears no date or version number. For an ECF80 it shows the Selector settings for the pentode section as 1-0-15, and is annotated with a footnote indicating "Model 45c only", which is clearly the type of valve tester in question. However, when attempting a gm test on the pentode section of a known good ECF80, the cathode appears to be open circuit.

Using the pin layout in the Brimar valve manual and carefully working through the settings using the Valve Base Wiring Chart in the Taylor 45c manual shows 1-0 to be correct for switches A and B, but there appeared to be no suitable setting for switch C. Further investigation uncovered another version of the Manual on the excellent website http://www.jogis-roehrenbude.de/Roe-Pruefer.htm, but with different connections shown in the Wiring Chart for switch positions 15 through 17, and another Valve chart with ECF80 settings of 1-0-16. Referring to the Wiring Chart, the 1-0-16 setting appears to be correct, but it does not work with my 45C. So which is the correct Valve Chart and Wiring Chart, and what is the problem with my tester?

With Anode set to 100v, Screen set to 60v, grid set to 15v, and a voltmeter connected to each pin of the B9A socket in turn, I rotated each of the Setting switches through each of the 18 positions and created a new chart based on the results. I deliberately chose these voltages so that it would be immediately obvious which of the valve electrodes the tester expected on each pin. As might be expected, there were a number of discrepancies between the Wiring Charts and the actual results, but only in switch positions 15 through 17.

I have attached this chart along with the two wiring charts I have found.

The obvious conclusion to be drawn from all this is that Taylor produced several versions of the 45c, each capable of testing a slightly different range of valves, but did not differentiate the design variations with model number suffiixes. Presumably, within the Taylor company they used the serial numbers to differentiate versions. Does anyone have any information on this?

If any forum member owns a copy of either the 45c Manual, or Valve Chart, could you please post a scan of the Wiring Chart (with any available version number or publication date), Socket Layout, and Serial Number so that we can compare them against those included here? The corresponding valve tables would also be useful if they are available in electronic form. As they are likeley to be too large to post here, they can be sent to me by PM .

If there is sufficient response, I will post an analysis here along with a chart of later valve types so that we can all benefit from the information. Hopefully, this should enable the more adventurous 45C owners to update the switch wiring of earlier 45Cs to a later, more complete version.
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