Change the Channels on RadioShack

It seems I'm the only one who's unimpressed with RadioShack's (RSH Quote) first-quarter results.

Shares of the electronics retailer recently were jumping $1.95, or 7%, to $29.67 after the company posted better-than-expected earnings. That adds to a big stock run in recent months as RadioShack works to turn around a series of dismal results.

Indeed, the company has slashed costs, improved margins and boosted its bottom line. But sales are still tanking, and that's not just because the retailer closed more than 500 stores. On a comparable-store basis, first-quarter sales plummeted 9.2% amid continued weakness in the company's wireless business.

This sales decline, as well as the stock's lofty levels, makes me wary.

I do applaud what RadioShack accomplished on an operational basis. Gross margin in the first quarter improved 370 basis points, and operating margin jumped 540 basis points to 7.5%.

Management said improved inventory control and product mix helped boost gross margin, while a decrease in payroll and advertising costs improved operating margin. CEO Julian Day and his team did a stellar job in that department.

RadioShack also managed its cash well in the quarter. Accounts receivables and inventories went down, while payables rose by nearly half the amount in the year-ago period. Without the repurchase of $45 million in stock, cash would have grown by $36.4 million.