@SilverBullet
It's all in the service manual, just do search for it on this site.
VR-10 for AM carrier adjust.
73
It's all in the service manual, just do search for it on this site.
VR-10 for AM carrier adjust.
73
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tuning cobra 2000 gtl
- Thread starter excavator701
- Start date
There should be a crystal that's been added to provide the added frequency coverage. It will be wired to the switch along with the big,fat crystal that's just inboard from the MB8719 PLL chip. The extra-channel switch will select one or the other crystal.
I recommend setting it on frequency for the normal 40 channels first. An added crystal to add another 40-channel band should have some sort of trimmer adjustment connected to it. Maybe a trimmer capacitor or even a small slug-tuned coil.
A common error made by someone installing this trick is to use wires that are just too long. Mounting the extra-channel switch in a convenient spot will put it too far from the factory-original crystal. The long wires needed to reach will disrupt the crystal's frequency calibration. Best way is to use a small relay, mounted next to the factory crystal, keeping the wires attached to the crystals as short as possible. The long wire to the switch will now carry only DC current. Won't disrupt the crystal circuit's frequency accuracy.
Thought I had a pic of that trick. Can't seem to find it.
If the upper channels aren't important to you, try connecting the factory crystal by itself without extra wiring in the circuit. Might simplify getting it aligned on frequency.
73
73
I recommend setting it on frequency for the normal 40 channels first. An added crystal to add another 40-channel band should have some sort of trimmer adjustment connected to it. Maybe a trimmer capacitor or even a small slug-tuned coil.
A common error made by someone installing this trick is to use wires that are just too long. Mounting the extra-channel switch in a convenient spot will put it too far from the factory-original crystal. The long wires needed to reach will disrupt the crystal's frequency calibration. Best way is to use a small relay, mounted next to the factory crystal, keeping the wires attached to the crystals as short as possible. The long wire to the switch will now carry only DC current. Won't disrupt the crystal circuit's frequency accuracy.
Thought I had a pic of that trick. Can't seem to find it.
If the upper channels aren't important to you, try connecting the factory crystal by itself without extra wiring in the circuit. Might simplify getting it aligned on frequency.
73
73
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