Uniden Grant XL PB-208 board. Can't get VCO frequencies to set. Alignment calls for AM L23 34.985 LSB L22 34.9835 USB L59 34.9865. I can not adjust it down any lower than 35.167 mhz. Changed the 11.325 crystal, changed L23 and check some diodes nothing made any difference.
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Help Uniden Grant XL
- Thread starter paulsbox
- Start date
This makes it sound as if the PLL is out of lock.
An unlocked PLL should not permit the radio to transmit, at all. FCC rules require a circuit that detects this "unlocked" condition and disables the transmitter when this happens.
Do you have a 'scope or a way to borrow one?
Never have learned how to troubleshoot a PLL circuit without a 'scope.
73
An unlocked PLL should not permit the radio to transmit, at all. FCC rules require a circuit that detects this "unlocked" condition and disables the transmitter when this happens.
Do you have a 'scope or a way to borrow one?
Never have learned how to troubleshoot a PLL circuit without a 'scope.
73
There is yet another possibility here. If the clarifier has been unlocked WITH extending the range of the slide ('jumping the resistors'); then the center freq of the clarifier will be more like at the 2 o'clock position - rather than at the 12 o'clock position. Try that next.
That is the reason I don't bypass those resistors as most clarifier mods ask to do. Sure it extends the clarifier slide; but it also makes it susceptible to drift, too much slide to dial someone in (IOW - too sensitive), and leaves the clarifier in a skewed position for its center slot. See this a few times. Just saying . . .
That is the reason I don't bypass those resistors as most clarifier mods ask to do. Sure it extends the clarifier slide; but it also makes it susceptible to drift, too much slide to dial someone in (IOW - too sensitive), and leaves the clarifier in a skewed position for its center slot. See this a few times. Just saying . . .
Update found problem, had the wrong ceramic capacitor in circuit. Had a 220pf a was suppose to be a 470pf. Thanks
i noticed you posted that the alignment instructions stated L59 for the USB adjustment, and the Grant XL does not have an L59.
which alignment procedure were you using?
also, there are only two 470pF caps in the loop oscillator circuit, C117 and C212.
which one of these caps was it?
the reason i ask is i'm having trouble seeing how such a minor change in part value made such a big difference in the frequency?
was the 220pf cap there from the factory?
LC
which alignment procedure were you using?
also, there are only two 470pF caps in the loop oscillator circuit, C117 and C212.
which one of these caps was it?
the reason i ask is i'm having trouble seeing how such a minor change in part value made such a big difference in the frequency?
was the 220pf cap there from the factory?
LC
gotcha.
thanks for the info on the PB-208 version. I've either never seen that version or have forgotten that i've seen one. LOL
LC
thanks for the info on the PB-208 version. I've either never seen that version or have forgotten that i've seen one. LOL
LC