There was a phase noise mod done to the early Paragons. When QST did
their product review, they uncovered a phase noise problem which Ten Tec
fixed by adding a filter to the output of the 723 voltage regulator
chip on the PLL board. This was mentioned in the QST review in the May
1988 issue. My Paragon schematic does not show voltage regulators on
either PLL board, but there is one on the oscillator board. However,
there is a regulator mounted on the chassis side wall just above the
microprocessor board. There is an extra filter here, mounted on a 5 lug
terminal strip. This may be the mysterious phase noise filter. It
certainly looks like a factory mod. The filter consists of a capacitor
and an inductor wound on a small plastic bobbin.
I have not experienced filter blow-by with my Paragon. It is serial
number 90B10491.
73,
Bob WB2VUF
DK2GZ@aol.com wrote:
>
> Hello
>
> my second rig is a Paragon I, first one is an OMNI 6+.
>
> I noticed a strong filter blow by and TenTec told me the problem is the phase
> noise of the Paragon, I saw some posts about a phase noise mod by replacing
> the pin-diodes in the Paragon.
>
> Is there an other mod to reduce the phase noise or to
> get a better selectivity with the Paragon?
> Use the 500 and 250 Hz filter in the Paragon and with the same filter setup,
> the OMNI 6+ is much better in selectivity during contests and strong signals
> on the band.
>
> 73 de Harry, DK2GZ
>
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