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1254pbigelow [2007/03/27 16:40] n5na created |
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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! | ||
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| **Features:** | **Features:** | ||
| - | 1. Great sensitivity (compared against the NRD-525) and the sensitivity is relatively consistent across the 100kc-30000kc receiving range. | + | - Great sensitivity (compared against the NRD-525) and the sensitivity is relatively consistent across the 100kc-30000kc receiving range. |
| - | 2. Good selectivity (for a 4kc filter) | + | - Good selectivity (for a 4kc filter) |
| - | 3. Reasonably stable | + | - Reasonably stable |
| - | 4. Excellent quality boards | + | - Excellent quality boards |
| - | 5. Easy to service (except for removing parts from the plated through holes) | + | - Easy to service (except for removing parts from the plated through holes) |
| - | 6. Convenient to use | + | - Convenient to use |
| - | 7. Informative, relatively easy to follow instructions | + | - Informative, relatively easy to follow instructions |
| **Suggested change:** | **Suggested change:** | ||
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| **Quirks noted and possible remedies:** | **Quirks noted and possible remedies:** | ||
| - | 1.) 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. |
| - | 2.) Reduced sensitivity on the lower half of the AM broadcast band. | + | * Reduced sensitivity on the lower half of the AM broadcast band. |
| - | Remedy: Put a jumper across R72, eliminating that input filter. | + | *Remedy: Put a jumper across R72, eliminating that input filter. |
| - | 3.) 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. | + | *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 |
| - | a) Snap-on RF choke on power cable | + | * Soldered on a shield on trace side of the board around the 1st Mixer section. |
| - | b) 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. |
| - | c) 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. |
| - | 4.) 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. |
| - | 5. ) 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. |
| - | 6.) 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. |
| - | 7.) A little bit of "thumping" due to slow synthesizer lock. Not too bad, really, considering | + | |
| - | the price. | + | |
| Paul | Paul | ||
