[Premium-Rx] Cubic R-3030A microprocessor noise

[mikea]

On Sat, Mar 20, 2004 at 09:37:56AM -0500, w3jn wrote:
> Hello the list. Well, after some messing around with the new R-3030A
> I discovered that a good deal of the digital hash was emanating from
> the speaker wires. To make a long story short, here's what I did to
> more or less resolve it:

> 1) left RX has shielded cable going from line audio to external
> audio amp. Bypassed the audio line with .01 caps to the screw on the
> chassis that holds in the serial interface card. Grounding the caps
> to the "ground" screw on the terminal strip did no good at all.

> 2) right RX is connected directly to a speaker. Both speaker lines
> bypassed to ground in a similar fashion as described above.

> 3) screwed down all of the modules. None of the screws were locked -
> I could hear the noise gradually decrease as I tightened each screw.
> Wonder why all of the modules were loose--? This radio may have been
> assembled from good modules robbed from other radios.

> Noise level on 28 MHz went from -60 on the meters to <-100 using the
> shop antenna (which is in close proximity to the receiver).

> Now I gotta get rid of the AM hiss. ALthough I perused the archives
fairly thouroughly, I didn't see any cures mentioned.

That's good to know. Have you considered also wrapping a couple of
turns of each audio wire/cable around a small toroid of the
appropriate material, to eat a little more of the noise, or are you
happy with things as they are?

-- 
Mike Andrews
mikea at mikea.ath.cx
Tired old sysadmin