Differences
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1254pbigelow [2007/03/27 16:48] n5na |
1254pbigelow [2007/03/27 16:49] n5na |
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| * Lots of birdies and display induced signals on the lower half of the AM broadcast band. | * Lots of birdies and display induced signals on the lower half of the AM broadcast band. | ||
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| *Remedy: Have attempted to shield out the multiplexing emissions by spray painting a graphite EMI/RF shield to the inside of the front cover. It helped a little bit. | *Remedy: Have attempted to shield out the multiplexing emissions by spray painting a graphite EMI/RF shield to the inside of the front cover. It helped a little bit. | ||
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| * Reduced sensitivity on the lower half of the AM broadcast band. | * Reduced sensitivity on the lower half of the AM broadcast band. | ||
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| *Remedy: Put a jumper across R72, eliminating that input filter. | *Remedy: Put a jumper across R72, eliminating that input filter. | ||
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| * FM intermod from strong FM stations. Just add 90 (2* 1st IF) to the received frequency | * FM intermod from strong FM stations. Just add 90 (2* 1st IF) to the received frequency | ||
| to detetmine offending frequency. | to detetmine offending frequency. | ||
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| *Remedy: Have tried with some success (but none totally satisfactory): | *Remedy: Have tried with some success (but none totally satisfactory): | ||
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| * Snap-on RF choke on power cable | * Snap-on RF choke on power cable | ||
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| * Soldered on a shield on trace side of the board around the 1st Mixer section. | * Soldered on a shield on trace side of the board around the 1st Mixer section. | ||
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| * Incorporated FM trap (from Radio Shack) in the antenna lead. | * Incorporated FM trap (from Radio Shack) in the antenna lead. | ||
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| * The rotary Encoder loosens up with use causing the frequencies to jump around (sometimes) when tuning from one step to another. | * The rotary Encoder loosens up with use causing the frequencies to jump around (sometimes) when tuning from one step to another. | ||
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| * Possible Remedy (have not tried yet): Sandwiching a large, black, felt washer between the tuning knob and the tuning knob recess to reduce play. | * Possible Remedy (have not tried yet): Sandwiching a large, black, felt washer between the tuning knob and the tuning knob recess to reduce play. | ||
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| * Hum from the power supply. | * Hum from the power supply. | ||
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| * Possible Remedy (have not tried yet): Install a 15V IC regulator in the power supply. | * Possible Remedy (have not tried yet): Install a 15V IC regulator in the power supply. | ||
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| * Deafening thump upon turning on the 1254 when using headphones. REALLY LOUD. | * Deafening thump upon turning on the 1254 when using headphones. REALLY LOUD. | ||
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| * Remedy: None yet although I suspect a large capactior may resolve this one. | * Remedy: None yet although I suspect a large capactior may resolve this one. | ||
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| * A little bit of "thumping" due to slow synthesizer lock. Not too bad, really, considering | * A little bit of "thumping" due to slow synthesizer lock. Not too bad, really, considering | ||
| the price. | the price. | ||
| Paul | Paul | ||
