Ombouw AVO buizentester MK4 (Techniek Overig)

door VCM163 , 17.12.2015, 22:10 (3075 dagen geleden) @ Loek

Just lovely!

I'd really like to build one of these to test and see how well it performs, please send me the information I need to build one myself!

All specifications that I have read, both in original AVO development documents stored at the IET in the UK and in the service manuals, have always had component lists and information that specify the meter in the AVO VCM Mk III, IV, CT160 & CT160A as being 30uA FSD and an internal resistance of 3250 Ohm (all of these documents have always had the calibration resistor at the same resistance which means that the meter has to be the same).

Similar looking meters but with a lower internal resistance and higher FSD currents, just like Ben Koehorst says, have been used in the AVO Transistor Testers and in the AVO Electronic Testmeter and some people have replaced the original meters with these meters without knowing the difference. You can adjust the meters from these other instruments to work in any of these AVO valve tester but you need to add some components to get it to work properly, series and shunt resistors to bring the meter to look like the original meter.

So as far as I know you will have to make sure that you calibrate the meter for 30uA FSD and have an internal resistance of 3250 Ohm, as long as you have the original values of the calibration resistors in your tester.

/Martin