[DSP-10] Having PLL Problems

Mon, 04 Aug 2003 16:29:31 -0400

I would not suspect both dead from transit, your freq counter may be 
loading down the circuit however, you may want to set a receiver next to it 
at the freq's you are trying to tune, and warp the oscillators and see if 
you can get a beat in the rx, am or sideband would be best.. If the freq 
counter is made for say ttl loading, it may be too much for the oscillator...

Just a thought .. Doug

At 03:03 PM 8/4/2003 -0500, you wrote:

>         Thanks for the recent discussion, and solutions on the serial
>clock pulse being rounded.  I used two inverters on a 74HC04 to square up
>the signal, and now it appears that my serial problems are solved.
>(Another step closer to getting on the air!)
>
>         I am still having some problems with both PLL in my system. Both
>of the PLL's are outputting 0hz (No output) on my frequency counter.  Both
>of the synthesizers are recieving a clean 10MHz signal from the Epson crystal
>oscillator.  Voltages on both synthesizer appear to be alright, 4.72V on
>the drain of Q101, and 3.67 on the drain of Q4. U107, and U108 voltages
>are as stated on Bob's PLL diagnostics sheet. Pin six of the U6 op-amp is
>on the bottom rail at .49V.
>
>         Is it possible that both of my J310 FETS are dead? They were 
> mailed to
>me in a regular envelope, so they might have been damaged in transit.
>
>                         Thanks,
>                         Christopher M. Best
>
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