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1254pbigelow [2007/03/27 16:46] n5na |
1254pbigelow [2007/03/27 16:51] n5na |
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**Quirks noted and possible remedies:** | **Quirks noted and possible remedies:** | ||
- | - 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. |
- | + | *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. | + | * Reduced sensitivity on the lower half of the AM broadcast band. |
- | + | *Remedy: Put a jumper across R72, eliminating that input filter. | |
- | - Reduced sensitivity on the lower half of the AM broadcast band. | + | * FM intermod from strong FM stations. Just add 90 (2* 1st IF) to the received frequency to detetmine offending frequency. |
- | + | ||
- | * Remedy: Put a jumper across R72, eliminating that input filter. | + | |
- | + | ||
- | - FM intermod from strong FM stations. Just add 90 (2* 1st IF) to the received frequency | + | |
- | to detetmine offending frequency. | + | |
*Remedy: Have tried with some success (but none totally satisfactory): | *Remedy: Have tried with some success (but none totally satisfactory): | ||
- | + | * Snap-on RF choke on power cable | |
- | * Snap-on RF choke on power cable | + | * Soldered on a shield on trace side of the board around the 1st Mixer section. |
- | + | * Incorporated FM trap (from Radio Shack) in the antenna lead. | |
- | * Soldered on a shield on trace side of the board around the 1st Mixer section. | + | * The rotary Encoder loosens up with use causing the frequencies to jump around (sometimes) when tuning from one step to another. |
- | + | ||
- | * Incorporated FM trap (from Radio Shack) in the antenna lead. | + | |
- | + | ||
- | - The rotary Encoder loosens up with use causing the frequencies to jump around (sometimes) when tuning from one step to another. | + | |
* 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. | ||
- | + | * Hum from the power supply. | |
- | - Hum from the power supply. | + | |
* 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. | ||
- | + | * Deafening thump upon turning on the 1254 when using headphones. REALLY LOUD. | |
- | - Deafening thump upon turning on the 1254 when using headphones. REALLY LOUD. | + | |
* 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. | ||
- | + | * A little bit of "thumping" due to slow synthesizer lock. Not too bad, really, considering the price. | |
- | - A little bit of "thumping" due to slow synthesizer lock. Not too bad, really, considering | + | |
- | the price. | + | |
Paul | Paul |