I eliminate the temperature change by cooling the unit. If I keep the unit cool, it never produces heat, consequently doesn't create a drifting problem due to heat. It also helps to touch up all the solder points for that section and to cover that section, using some wisdom of course, with hot glue. Old-school used to do it with wax. Insulated and stabilize it with hot glue.
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Galaxy radio drift
- Thread starter Larry A McClanahan
- Start date
In most of the cases X3 is source of major drift. You must stabilize it's temperature, that's all. Tested and verified.
Google for: resistor crystal oven.
Mike
Google for: resistor crystal oven.
Mike
About half of the 959's I'd worked on had a bad/weak loop osc xtal. So I replaced it and that helped some. But these were in older versions of the 959 - just saying . . .
Installed fan and grill on under side of my dx2547, same board as dx959b. Installed 5p cap across xtal3 pins. Touched up all solder points associated with that section. Covered section, to include xtal3 with hot glue as an insulator. Realigned. This will get you to the point to where your stability will be so close you won't notice it. But, you could instead as others have pointed out, install a thermistor as a crystal oven. That would solve your problem in the cold weather months. Adding the thermistor to the rest of this will get you as stable as you will need on that radio.
Just need a little clarification here, are you using the fan to ventilate the inside of the case?
You don't want to use the fan to draw the air out because the air will seek the path of least resistance. You always should force the air into the unit.
i have never done it, but i have wondered if changing out the clarifier pot for a 10 turn pot might stabilize these rigs a bit.
I have also wondered if changing out some of the components associated with each VCO tuning can in order to increase the amount of turning needed to make a tuning change might make some differences.
LC
I have also wondered if changing out some of the components associated with each VCO tuning can in order to increase the amount of turning needed to make a tuning change might make some differences.
LC
I don't see that helping. But I highly recommend very carefully retinning all the connections Associated on the underside of the board of the entire oscillator circuit.
Special note. C-130 will interact in a negative way with D49 if it stands up straight against D49. Gently bend it to the left toward the brown connector. It contributes to the instability of the circuit. You will have to realign after you bend it.
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I wasn't that crazy about this radio straight out of the box. But after a series of upgrades and improvements I am very pleased with this radio.
Now you're gettin' it.
Back in the days - they used to use foil shields to offset some of the "proximity" event you are having.
It's why they say SMD are superior to discrete - simply by inductive effects of lead length in the construction of the device. I tend have more favoritism to discretes because by convenience alone, easy to repair - it shows' though, that they are simply too lazy to install a foil shield where it is needed whether you have SMD there or not.
Now what they won't tell you is they do - and it "covers" the area - anyone with a recent radio full of SMD will show you a cover of solder and tin over the area - and that's the frequency sensitive area, where the VCO is. Look on the bottom and they've used the second (Bottom) half of the dual foil board sheet as the ground plane for the top side which is all the SMD sandwiched in between the foil cover and the foil backing.
So that tells me that they are full of it (Engineering Staff at the Remainnameless Brand for now) and they still have to protect the circuit from itself.
So keep going - I hope your idea can help solve some problems with stability (like the proximity of leaky parts) others may not catch.
Back in the days - they used to use foil shields to offset some of the "proximity" event you are having.
On a secondary note, someone on another forum brought to our attention how some caps - when they are rolled, don't always have their polarity and outer conductor set - oriented properly. Some caps - like Disc are moot points but if they have a plate that is misaligned, you might wind up getting more than you bargained for, because that outer "wind" might be the signal side and will radiate ...
A good rework of this is located here, at CB Tricks, it's in the forums and I'd need permission to post it here but if you have access you can find this article here...
http://www.cbtricks.com/forum/index.php?topic=7692.msg145489#msg145489
But if you can't I can go an fetch it and re-post it here with permission..
But in light of the article - you may have just hit on something that is a problem even for an engineer. Because it deals with construction on two fronts.
One the physical component - if the plates placed next to another part can interact, they will - and add an artifact to the design - the above article can show this as a coupling and interaction between live plates too close to the exterior shell of the component wrapper.
Two - location of component - If the part has to act as a bypass, does the part have the best and least reactive lead dress to ground - and does the ground plane foil in the area - properly tamed with bypass and or ripple filtering in itself to prevent propagation of signal noise into other location on the board itself?
A good rework of this is located here, at CB Tricks, it's in the forums and I'd need permission to post it here but if you have access you can find this article here...
http://www.cbtricks.com/forum/index.php?topic=7692.msg145489#msg145489
But if you can't I can go an fetch it and re-post it here with permission..
But in light of the article - you may have just hit on something that is a problem even for an engineer. Because it deals with construction on two fronts.
One the physical component - if the plates placed next to another part can interact, they will - and add an artifact to the design - the above article can show this as a coupling and interaction between live plates too close to the exterior shell of the component wrapper.
Two - location of component - If the part has to act as a bypass, does the part have the best and least reactive lead dress to ground - and does the ground plane foil in the area - properly tamed with bypass and or ripple filtering in itself to prevent propagation of signal noise into other location on the board itself?
It's why they say SMD are superior to discrete - simply by inductive effects of lead length in the construction of the device. I tend have more favoritism to discretes because by convenience alone, easy to repair - it shows' though, that they are simply too lazy to install a foil shield where it is needed whether you have SMD there or not.
Now what they won't tell you is they do - and it "covers" the area - anyone with a recent radio full of SMD will show you a cover of solder and tin over the area - and that's the frequency sensitive area, where the VCO is. Look on the bottom and they've used the second (Bottom) half of the dual foil board sheet as the ground plane for the top side which is all the SMD sandwiched in between the foil cover and the foil backing.
So that tells me that they are full of it (Engineering Staff at the Remainnameless Brand for now) and they still have to protect the circuit from itself.
So keep going - I hope your idea can help solve some problems with stability (like the proximity of leaky parts) others may not catch.
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