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1254pbigelow [2007/05/21 00:40] (current) |
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| ====== 1254 Review by Paul Bigelow ====== | ====== 1254 Review by Paul Bigelow ====== | ||
| - | **From the Ten Tec Reflector April 1, 1998** | + | **From the Ten-Tec Reflector April 1, 1998** |
| I have built the 1254 receiver and it is a nice little unit. A real joy to build, use and tune around. I haven't had this much fun in ages! | I have built the 1254 receiver and it is a nice little unit. A real joy to build, use and tune around. I haven't had this much fun in ages! | ||
| Line 20: | Line 20: | ||
| **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: Have tried with some success (but none totally satisfactory): | |
| - | * Remedy: Put a jumper across R72, eliminating that input filter. | + | * Snap-on RF choke on power cable |
| - | + | * Soldered on a shield on trace side of the board around the 1st Mixer section. | |
| - | - FM intermod from strong FM stations. Just add 90 (2* 1st IF) to the received frequency | + | * Incorporated FM trap (from Radio Shack) in the antenna lead. |
| - | to detetmine offending frequency. | + | * The rotary Encoder loosens up with use causing the frequencies to jump around (sometimes) when tuning from one step to another. |
| - | + | ||
| - | Remedy: Have tried with some success (but none totally satisfactory): | + | |
| - | + | ||
| - | * 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. | + | |
| - | + | ||
| - | - 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 | ||
