VCO Alignment

[Bob Wehking]

I have a problem with the VCO voltage readings. When I tune L30 to read 6.00 v at 4000, I get the following: The second set of numbers is when the core of L30 is turned all the way down. Any ideas?


80M    3500    2.12V      4.14V              4000        6.00V    7.93V
40M    7000    1.92V      5.11V              7300        3.68V    7.90V
30M    10000    7.84V    7.92V              10150      7.90V    7.93V
20M    14000    7.91V    7.91V              15000      7.91V    7.91V
17M    18000    7.90V    7.91V              18200      7.91V    7.91V
15M    21000    2.06V    2.48V              21450     2.35V     2.81V
12M    24800    7.90V    7.91V              25000     7.93V     7.91V  
10M    28000    7.90V     7.90V              28800    7.90V     7.91 V


Bob
WB8DDI
K2# 4998
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[Jim Younce]

Bob:

You have a definite problem in the PLL Circuits.  The PLL Circuits are on
the schematic of the RF Board Page 1 of 4 and is everything on the top half
of the page.

You need to check all the componets in the PLL circuit.  It appears that the
PLL is unlocked in all but three bands.  Any reading near 8 volts indicates
an unlocked condition.  It appears that the only bands that are in a locked
condition are 80 - 40 -15 Meters.  The rest are not in lock.  One of the
major problems can be the wiring of the Thermistor Board.  Also make sure
you have the coreect diodes installed in D17-D26.  Make sure all pins are
soldered on K13 - K14 - K15.  Also check the resistance across RFC15 and
make sure it is not open. It is very easy to damage it while installing it.

73 & GL

Jim Younce K4ZM


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