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1254pbigelow [2007/03/27 16:51] n5na |
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| - | ====== 1254 Review by Paul Bigelow ====== | ||
| - | **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! | ||
| - | |||
| - | **Features:** | ||
| - | |||
| - | - Great sensitivity (compared against the NRD-525) and the sensitivity is relatively consistent across the 100kc-30000kc receiving range. | ||
| - | - Good selectivity (for a 4kc filter) | ||
| - | - Reasonably stable | ||
| - | - Excellent quality boards | ||
| - | - Easy to service (except for removing parts from the plated through holes) | ||
| - | - Convenient to use | ||
| - | - Informative, relatively easy to follow instructions | ||
| - | |||
| - | **Suggested change:** | ||
| - | |||
| - | Mount an RCA jack with a nylon washer on the outside to the back panel to reduce stress on the board. | ||
| - | |||
| - | **Quirks noted and possible remedies:** | ||
| - | |||
| - | * 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. | ||
| - | * Reduced sensitivity on the lower half of the AM broadcast band. | ||
| - | *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): | ||
| - | * 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. | ||
| - | * Hum from 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. | ||
| - | * 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. | ||
| - | |||
| - | Paul | ||
