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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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30th Jan 2016, 9:06 pm
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#1 |
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Pentode
Join Date: Oct 2010
Location: Fareham, Hampshire, UK.
Posts: 112
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Marconi 2022C off frequency
Hi
I have just bought a Marconi 2022C, worked OK when it arrived. I was about to use it in anger and suddenly all frequencies below 62.5MHz are way way off (and not stable) that keyed in and displayed on the front panel. I have looked at various other threads on the forum, and the suggestion is that IC2 (OM345) had died. Is there an easy way of confirming this before I dive in with soldering iron etc. (There are two sellers of these on eBay, has anyone used either of them ?) Cheers Richard |
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30th Jan 2016, 10:08 pm
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#2 |
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Dekatron
Join Date: Feb 2005
Location: St.Ippolyts, Hitchin, Hertfordshire QRA IO91UW
Posts: 3,517
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Re: Marconi 2022C off frequency
Yup, measure across all of the pins of the device to ground, if more than one of them shows around 7vdc it is toast
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Engineers make things work and have spare bits when finished |
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4th Feb 2016, 2:10 pm
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#3 |
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Pentode
Join Date: Oct 2010
Location: Fareham, Hampshire, UK.
Posts: 112
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Re: Marconi 2022C off frequency
Hi
All now working again. IC2 had failed, just replaced this with a mmic based one and all is OK  . No need to re-calibrate as this is in the PLL circuit Cheers Richard m0ysr |
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