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Vintage Test Gear and Workshop Equipment For discussions about vintage test gear and workshop equipment such as coil winders. |
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24th May 2009, 5:53 pm | #1 |
Pentode
Join Date: Mar 2006
Location: North Norfolk, UK.
Posts: 181
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AVO All Wave Oscillator
I have a hunch that my AVO is not working properly. I have an output. The problem I think, is that I can't adjust the output level with the multiplier and output slide wire control. How would you test it ? I have a scope.
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David Goodall |
24th May 2009, 6:24 pm | #2 |
Nonode
Join Date: Mar 2008
Location: Aberdeen, UK.
Posts: 2,838
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Re: AVO All Wave Oscillator
Hello David,
Do you have the Handbook ? Cant remember if I obtained mine as a free download off this site or BAMA. If you experience trouble downloading it, let me have your email address in a PM, and I'll try & send you a pdf attachment. Sounds like a dodgy switch. Regards, David |
24th May 2009, 6:49 pm | #3 |
Pentode
Join Date: Mar 2006
Location: North Norfolk, UK.
Posts: 181
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Re: AVO All Wave Oscillator
Thanks David. Yes, I do have the manual. Hope it's not the switch ! I think the best thing I can do, is plug it into the scope and report back what I see. I'm a bit of a novice, so it may even be working properly !
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David Goodall |
24th May 2009, 8:50 pm | #4 |
Dekatron
Join Date: Feb 2007
Location: Leominster, Herefordshire, UK.
Posts: 16,526
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Re: AVO All Wave Oscillator
Probably best to put a 56ohm resistor across the 'scope input to load the generator output. If the generator output is calibrated in volts or millivolts, the figures should be roughly equal to 1/3 of the peak to peak voltage on the 'scope. (1/(2*root2) to be precise)
Chris |
24th May 2009, 9:06 pm | #5 |
Nonode
Join Date: Mar 2008
Location: Aberdeen, UK.
Posts: 2,838
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Re: AVO All Wave Oscillator
David, Set your scope's "Yamp"'s mV/Div to 5mV, and your Osc to x10 & 500micro-volts, at say 500hz. Then set your scope's t/base to 2mS, and you should be seeing some nice sinewaves. Use the "fine" controls on your scope to ge a steady display, then change your Osc to x100, and see if you need to adjust your scope's Yamp accordingly.
Have you got a bnc connector(same as on the scope's i/p) on your osc ? Or just the old-fashioned crock clips on the end of a lead ? Each x10 change in Ocs o/p & freq should be correspondingly matched by changing your scope's mV/Div & timebase to maintain a sinewave within a chosen cm square, or number of squares on the graticule. If you have a double beam scope - feed a signal of known freq & amplitude(internal 1Khz calib.?) into Y1, and the Osc into Y2 and compare. I think that the internal oscillator's(V1) max o/p is actually 1V, and is then attenuated down to less than 500microvolts by the switch & pot. You'll need the scope's probe & crock clip to carry out tests internally. Be careful. Regards, David |
25th May 2009, 6:39 pm | #6 |
Pentode
Join Date: Mar 2006
Location: North Norfolk, UK.
Posts: 181
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Re: AVO All Wave Oscillator
O.K. All is now well. The range switch was to blame on range 5. All checked out well on the scope. Thank you for the guidance David.
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David Goodall |