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Old 26th Mar 2023, 9:11 pm   #273
frsimen
Heptode
 
Join Date: Jan 2011
Location: Croydon, London, UK.
Posts: 766
Default Re: Help needed with - Racal Dana 9081

Hello Mark,

The output at TP7 is a very good level, so there is no need to worry about the voltages around Q4 and Q6's emitter.

Everything you have measured looks good except for the voltage on IC1 pins 5 and 6. They should both be the same and 12.3V. It look like you may have had a poor contact for that measurement.

Can you measure the range of frequencies that are on TP7, as that is the most important thing here? You should be able to set the fine controls to give 300kHz and it should be reasonably stable. Expect a drift on the Hz/10s of Hz digits on your external frequency counter, that's normal but it shouldn't be worse than that and it should be a slow drift. The controls should allow the frequency to be changed by a little either side of 300kHz.

If that is what you see, move over to TP1. You should see the same waveform and frequency there. If you don't, change IC1.

Paula
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