With the low side being way below expected I would suspect the capacitor it seems like the entire frequency range is shifted. On thing to not in tuning the 503 is some of the ranges are not tuned for frequency range but harmonic suppression as well as making the expected range.
Zen
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-----Original Message-----
From:
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[email protected]> On Behalf Of Jared Cabot via groups.io
Sent: Tuesday, April 19, 2022 11:32 AM
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[email protected]Subject: Re: [TekScopes] SG503 - low output frequency on 100-250MHz range?
Ok, I gave LR140 a tweak, and found that squeezing the coils closer shifts the frequency range down a little (a couple MHz) and spreading the coils apart raises it by the same.
I also found that the unit is flashing the display to say the output is unleveled above 228MHz. So at the moment I have the inductor set so that the maximum frequency is 228MHz, this means at the moment the 100-250MHz range has a span from 85MHz to 228MHz
So still on the hunt.... I'll have to look deeper to see if some component is out of spec. I might give the variable capacitor a careful teardown and clean too.
