"Gary Poland" <[EMAIL PROTECTED]> made an utterance to the drakelist gang
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David,
I have seen several TR-7's in the past that the +25 ( 23.5 to 25 ) dc
supply was low and slow up or not allow the PLL to lock on 20 and 10 meters.
The 25 volts is the tuning voltage for the VCO. Sometimes the 78L24 vdc
regulator is bad or not getting enough input voltage, typically around 30
volts. Many times its the gap between the transformer cores, they have a
tendency to slip apart. I use hot glue to keep the gap closed and raise the
voltage back to 30 volts or better. I had at least one power supply board
that I had to replace C2117 with a .033 mfd to achieve the 30 volts needed
for the 78L24. I have also seen boards with the 15 ohm collector resistors
bridged with 68 ohm resistors to increase the voltage.
73, Gary
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