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| HP8656A signal generator - external timebase |
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| Greg01:
Hoping someone can help. I have an external time base (10 MHz) which I have connected to the time base input connector. I have checked that the time base jumper on the LF loop assembly is in the 10 MHz position. With a frequency counter on the time base output connector, I do not see any change in the frequency when the external time base is connected as there is no change in the generator output frequency (there is approx 20 Hz difference between the internal and external time bases). I cannot find any information regarding the min/max levels of external time base voltage the 8656A requires. Can anyone offer some helpful advice please? Greg |
| wn1fju:
Figure 3-7 of the manual (downloaded from Keysight) says: "Female BNC connector (J3) accepts an external 1, 5 or 10 MHz (+/-0.005%) time base reference input at a level of 0.2 to 0.4 Vrms into 50 ohms." |
| Greg01:
Hi wn1fju, Thank you for the reply. I had read the service manual which does not give the input amplitude required but on reading the operation manual (your ref.) I see the levels. My ext ref outputs about 4.5V @ 10 MHz so made up an attenuator and now have 200mV but still no luck with the external oscillator being accepted. I have a feeling something may have been disconnected internally so my next job will be to see if this is so. I bought the SG in an operational condition but the keyboard needed some work which was very successful thanks to Youtube and the people who publish. There is some output instability which appears to be coming from the LF board but thought I would try an external ref first to see if the ref oscillator was contributing to the problem. I appreciate your input - thank you again. Greg |
| rhb:
I don't have an 8656A , but the manual quote suggests a menu item buried somewhere. Good luck. Reg |
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