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When the output falls is the frequency outside the selected range? I have one that will let me set the frequency quite a bit low and high on the selected range but the leveling is not specified outside the selected range frequency range So this might be "normal" behavior. I just did a full calibration on one of the units I have. The manual calls out NOT to adjust the coils or trimmers unless necessary. And if those need adjustment you will need a spectrum analyzer to get the adjustment correct as these have a great deal of effect on the harmonic content of the waveform.
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Zen -----Original Message-----
From: [email protected] <[email protected]> On Behalf Of romeo987 Sent: Saturday, July 24, 2021 4:59 AM To: [email protected] Subject: [TekScopes] SG503 question Guys, Apologies in advance if I am doing the wrong thing; I posted this question on the TM500 group a while back, but there seems to be little activity over there, while there is a lot of action here ( I have been following for quite a while), and a lot of it to do with the TM500 world. The question is as follows: I have a couple of SG503s that I decided recently to ¡°get working¡±. Largely successful to the extent that I can monitor the output level to the required accuracy without the special Knick knacks called out in the manual. But one interesting effect I notice on both units (to a greater extent on one than the other) is, that on the 5-10 and 10-20 MHz ranges, at the extreme low limit of the dial (below 5 and 10MHz respectively) the output falls away to zero. Only on these two ranges. I have spent a bit of time rummaging around in the circuit, and at the moment it looks as if Q300 (the current source for the oscillator, driven by the leveling amp) can¡¯t quite push enough current to keep the oscillator Q130 going. But before I spend a lot more time, I would like to hear whether this is a common effect, and whether there is a known solution. Any advice gratefully received . |
