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Old 23rd May 2023, 8:43 pm   #1
RogerWalker
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Default Marconi TF886 Circuit Magnification Meter

Does anyone have a circuit or manual for the TF886 Q-meter, please? I have one of these in a fairly shabby state and might consider restoring it - but not without a circuit or better still, a manual. I might also sell it, if there's anyone interested.
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Old 23rd May 2023, 10:45 pm   #2
Radio Wrangler
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Default Re: Marconi TF886 Circuit Magnification Meter

To make it work, you also need the matching signal sources. They are special with unusually low output impedance. For use with other sig gens, Marconi sold step-down matching transformers.

There were two sig gens, and the TF886 contains two Q meter circuits to cover the full frequency range.

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Old 24th May 2023, 8:37 am   #3
Dickie
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Default Re: Marconi TF886 Circuit Magnification Meter

You might have more luck by asking on the Marconi instruments group here:

https://groups.io/g/Marconi-Test-Instruments
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Old 24th May 2023, 11:35 am   #4
RogerWalker
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Default Re: Marconi TF886 Circuit Magnification Meter

Thanks for the comments so far and special thanks to Dickie for suggesting the MI user group. I have posted there and will let you know whether I get any help there. It seems predominantly digital in content so something as old as an 886 may not register on their radar. I live in hope.
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Old 24th May 2023, 1:43 pm   #5
WME_bill
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Default Re: Marconi TF886 Circuit Magnification Meter

TF886 Q meter.
Roger,
while you may have luck with the User Group, often this forum can help. As we are all getting a bit aged now, like the equipment we are trying to get working, the response time is not quite as quick!
I attach the manual and 1949 Sales brochure for your model.
I also have the manualsand the equipment for the final model TF1245+signal generators TF1246 (40khz - 50Mhz) and TF1247 (20-300Mhz) which are rather more detailed about the operating principles.
I also have a very useful Marconi booklet "Measurements by Q meter" of 1951 which covers operating instructions and methods of measurement etc for both the TF329 and TF886. I an scan that if you want it.
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File Type: pdf TF886 Q meter 1949-wm.pdf (2.37 MB, 30 views)

Last edited by WME_bill; 24th May 2023 at 1:53 pm.
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