Re: [Repeater-Builder] GE Mastr II PLL vs. Multiplier (crystal) exciter in duplex service.

[Kevin Custer]

Hi Wade, I'm sorry, but I have to disagree with your stability theory on the GE Mastr II PLL high-band exciter.  If you refer to the PDF manual for the PLL exciter: <http://www.repeater-builder.com/ge/lbi-library/lbi-30398n.pdf>  You will see under the "Description" the exciter utilizes the 12th multiple of the FM ICOM to lock the VCO on frequency.  It goes into more detail about this in the "Circuit Analysis" section of the same manual.  So, the FM ICOM's multiplication certainly does factor into the stability of the PLL exciter, and one can generalize it has the same frequency stability as its multiplier counterpart.  In addition, the modulation of the PLL exciter is produced in the crystal reference (FM ICOM) as well, and is also multiplied up to the desired deviation.  Since the time constant of the Lead/Lag filter allows for near instantaneous correction of the VCO, changes in frequency at the audio rate are superimposed onto the output frequency. Hope this helps... Kevin Custer Wade Lake wrote: Kevin Custer wrote: The advantage here is the same frequency stability is achieved by the use of the quartz reference Actually, a PLL oscillator is much more stable than a multiplied crystal oscillator. because with a multiplied quartz oscillator, frequency drift and frequency error (usually deviation as well) is multiplied by 12, at least in the case of the High band GE MASTR II. Not to dissagree with you Kevin, your answer is good, I think you nailed it. I just wanted to point out that stability is a very strong point of the PLL. Since it operates on the desired frequency, no frequency error/drift is multiplied. Wade - KR7K Yahoo! Groups Links To visit your group on the web, go to: http://groups.yahoo.com/group/Repeater-Builder/   To unsubscribe from this group, send an email to: [EMAIL PROTECTED]   Your use of Yahoo! Groups is subject to the Yahoo! Terms of Service.