Thanks, Bob. First quarter 2017 end user net revenues were $12.5 million or 88% of net revenues compared to $9.6 million or 93% of net revenues in the fourth quarter. OEM net revenues were $1.7 million or 12% of net revenues, up from $692,000 or 7% for the fourth quarter. Net revenues from markets outside of semiconductor test were $3.7 million or 26% of net revenues compared with $4.3 million or 42% of net revenues in the fourth quarter.
Our first quarter gross margin was $7.7 million or 55% as compared with $5.4 million or 53% in the fourth quarter. The improvement in the gross margin was primarily the result of a better absorption of our fixed manufacturing costs due to significantly higher revenues partially offset by an increase in our consolidated component material costs, which grew from 32.1% in the fourth quarter to 33.2% in the first quarter.
While our fixed manufacturing cost declined from 13% of net revenues in the fourth quarter to 10% of net revenues in the first quarter, they increased in absolute terms by $166,000 or 13% to $1.5 million. The increase in first quarter manufacturing costs were the result of higher levels of facility cost as well as increased selling and benefit expense due to additional staff hired during the first quarter in response to increased manufacturing activity.
While there were increases in the component material costs of both of our product segments, the increase in consolidated component material costs in the first quarter was primarily the result of an increase in the component material costs of our Thermal Solutions segment, which grew from 30.5% in the fourth quarter to 31.7% in the first quarter while our EMS product segment saw its component material cost increase from 35.0% to 35.1% sequentially. These increases were both a result of a less favorable product and customer mix in the first quarter as compared to the fourth quarter.
Selling expense was $1.7 million for the first quarter compared to $1.4 million in the fourth quarter, an increase of $301,000 or 22%. Higher levels of sales commission expense in our EMS product segment represented half of the increase in selling expense. In addition, there were increases in travel costs in our Thermal Solutions division as well as higher levels of advertising expense in our EMS product segment.
Engineering and product development expense was $935,000 for the first quarter compared to $782,000 for the fourth quarter, an increase of $153,000 or 20% sequentially. The increase was related to higher levels of salary and benefit costs and product development materials.
General and administrative expense grew from $1.6 million in the fourth quarter to $2 million in the first quarter, an increase of $353,000 or 22%. The increase was primarily the result of higher levels of salary and benefit costs and travel related to acquisition related activities. To a lesser extent, there were also increases in compliance costs, restricted stock compensation, officer bonuses, and professional services.
Other income was $41,000 in the first quarter compared to other expense of $2,000 in the fourth quarter. This change is primarily the result of foreign transaction gains of $12,000 in the first quarter compared to foreign transaction losses of $22,000 in the fourth quarter. Interest income was $24,000 for the first quarter, up from $15,000 in the fourth quarter.
We accrued an income tax expense of $1.1 million for the first quarter compared to $612,000 accrued in the fourth quarter. Our effective tax rate declined to 35% in the first quarter from 38% in the fourth quarter. The decrease in our effective tax rate was the result of several factors including changes in the mix of domestic and foreign earnings with our foreign earnings and their lower effective tax rate representing a higher portion of consolidated earnings as well as the impact of higher than expected deemed dividend income in the fourth quarter.
At March 31, 2017, our deferred tax assets were $1.1 million and our remaining net loss carry-forward was $1.2 million for domestic state (primarily California). During the first quarter, we utilized the remaining net loss carry-forward in our German operation and this operation began accruing income tax expense for the first time in many years. We expect our effective tax for the balance of 2017 to be in the range of 35% to 37%.
First quarter net income was $2.1 million or $0.20 per diluted share compared with fourth quarter net income of $1.0 million or $0.10 per diluted share. Diluted average shares outstanding were 10,295,000 at March 31 and during the first quarter, we issued 55,000 restricted shares to directors and executive officers while we repurchased 13,883 shares at a net cost of $62,000 or $4.49 per share. As of March 31, 2017, we have repurchased a cumulative total of 297,020 shares or approximately 2.8% of our outstanding common stock at a net cost of $1.2 million or $4 per share.
Amortization and depreciation expense was $150,000 for the first quarter and EBITDA was $3.3 million for the first quarter, up 88% from the $1.8 million in EBITDA reported for the fourth quarter.
Consolidated headcount at the end of March, which includes temporary staff, was 123, an increase of 4 staff from the level we had at December 31.
I'll now turn to our balance sheet. Cash and cash equivalents at the end of the first quarter were $27.5 million, down $1.1 million from December 31. We currently expect cash and cash equivalents to increase throughout 2017 before the impact of funding any proposed acquisition.
Accounts receivable almost doubled to $9.8 million at March 31, increasing $4.4 million due to strong sales into Asia where credit terms are longer than in the US and Europe.
Inventories increased $245,000 to $3.9 million at quarter-end.
Capital expenditures during the first quarter were $114,000, double the level spent in the fourth quarter.
Bob provided consolidated and segment revenue and booking data earlier in the call. The backlog at the end of December was $8.2 million, up from $7.4 million at the end of December and represented the highest level of backlog seen in almost a decade.
In terms of our financial outlook, as noted in our earnings release, we expect that net revenue for the quarter ended June 30, 2017 will be in the range of $13 million to $14 million and that our earnings will range from $0.13 to $0.18 per diluted share. We currently expect that our Q2 2017 product mix will be slightly less favorable as compared with the first quarter and that the second quarter gross margin will range from 51% to 54%.
Operator, that concludes our formal remarks, we can now take questions.