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Old December 18th 03, 08:07 PM
Bill Graham
 
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Default Knwd TS-830S Alignment Question/Problem (PLL/VFO)

The TS-830S service manual's alignment procedure, Step 9 ("VCO adj &
check") contains the PLL coil adjustments for the various bands. The
procedure calls for a frequency counter and DVM.

Here's my confusion/problem: the measurement point for the frequency
counter is shown as:
RF(PLL) - TP3(D40)

I interpret this to mean EITHER:
TP3 on the RF assy, OR
D40 on the PLL assy

But, perhaps I am mistaken ... I see a vast difference in the signal
levels at these two test-points.

The signal at PLL-D40 appears to be correct (i.e., when I align the
tuning coils specified to produce a 4.00 VDC level on the DVM at
PLL-TP1, I measure a 1.058 vrms signal at PLL-D40).

But, the 2nd step in this section then calls for a check of the signal
level at RF-TP3 to be 1V (+3/-2 db).

But, the signal level at RF-TP3 is so weak as to be almost un-readable
(I measure ~5.0 millivolts).

Final info: I measured the signal level on the RF assy at the junction
of L44 and L40, and it is approximately 95% of PLL-D40 total, so I know
that: a) the VCO cable carying the signal is making good connection and
not hi-Z, and b) L44 is NOT open, c) C61 is NOT shorted, and d) L40 is
PROBABLY not hi-Z.

Which all leaves me with a partial (or full) short at RF-TP3 (what
_should_ the inductance value be of the primary of T3 on the RF unit
be?), or am I simply not interpreting the alignment test-points and
procedure correctly?

BTW: the frequency at PLL-D40 is ~1500 Hz too high.

Anybody have any ideas???



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