[eagle] Re: 70 cm Receiver IF Spurs - Problem Solved

Howard Long eagle at howardlong.com
Sat Jun 16 11:11:51 PDT 2007


 
Folks

> The 70 cm Receiver spur problem has been solved.  
> Click here 
>
<http://www.juanr.com/pages/hobbies/ham_radio/Eagle/CAN-Do_Noise_Troubleshoo
ting.htm>  
> for details.

This is very interesting. FWIW in the original SDX PSU design I had in San
Francisco last year is an SMPS using the LM2672 device. These can be fitted
with an AC coupled SYNC signal to override the internal default SMPS
frequency. I selected 375kHz for my unit (6MHz divided by 16) to ensure its
harmonics were outside the 10.7MHz IF passband. If the external SYNC fails
the internal SMPS oscillator takes over.

Cheers, Howard



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