| Note 1 - Summary of Significant Accounting Policies (Tables)
 | 12 Months Ended | 
| Sep. 30, 2023 | 
|---|
| Notes Tables |  | 
| Schedule of Cash and Cash Equivalents [Table Text Block] | 
		
			| (In thousands) |  | September 30, 2023 |  |  | September 30, 2022 |  |  
			| Cash and cash equivalents: |  |  |  |  |  |  |  |  |  
			| Cash including money market accounts |  | $ | 11,360 |  |  | $ | 16,635 |  |  
			| Money market funds |  |  | 26,467 |  |  |  | 15 |  |  
			| Total cash and cash equivalents |  | $ | 37,827 |  |  | $ | 16,650 |  |  | 
| Accounts Receivable, Allowance for Credit Loss [Table Text Block] | 
		
			| Year Ended |  | Balance atBeginning of Year
 |  |  | Additions(Recoveries)
 Charged to
 Costs and
 Expenses
 |  |  | LessWrite-offs
 |  |  | Balance at End ofYear
 |  |  
			| September 30, 2023 |  | $ | 79,000 |  |  | $ | - |  |  | $ | - |  |  | $ | 79,000 |  |  
			| September 30, 2022 |  | $ | 79,000 |  |  |  |  |  |  | $ | - |  |  | $ | 79,000 |  |  | 
| Schedule of Inventory, Current [Table Text Block] | 
		
			|  |  | September 30, 2023 |  |  | September 30, 2022 |  |  
			| (In thousands) |  |  |  |  |  |  |  |  |  
			| Raw materials |  | $ | 73,657 |  |  | $ | 69,142 |  |  
			| Work-in-process |  |  | 1,462 |  |  |  | 4,592 |  |  
			| Finished goods |  |  | 29,696 |  |  |  | 10,803 |  |  
			| Inventories, gross |  |  | 104,815 |  |  |  | 84,537 |  |  
			| Inventory reserve |  |  | (6,760 | ) |  |  | (2,329 | ) |  
			| Inventories, net |  | $ | 98,055 |  |  | $ | 82,208 |  |  | 
| Schedule of Finite-Lived Intangible Assets [Table Text Block] | 
		
			|  |  | September 30, 2023 |  |  
			| (In thousands) |  | UsefulLife
 (Years)
 |  |  | Gross CarryingAmount
 |  |  | AccumulatedAmortization
 |  |  | Net Book ValueAmount
 |  |  
			| Customer relationships |  |  | 15 |  |  | $ | 4,894 |  |  | $ | 1,582 |  |  | $ | 3,312 |  |  
			| Certifications |  |  | 8 |  |  |  | 584 |  |  |  | 267 |  |  |  | 317 |  |  
			| Trademarks |  |  | 8-10 |  |  |  | 1,333 |  |  |  | 700 |  |  |  | 633 |  |  
			| Patents |  |  | 20 |  |  |  | 1,119 |  |  |  | 165 |  |  |  | 954 |  |  
			| Developed Technology |  |  | 10 |  |  |  | 311 |  |  |  | 22 |  |  |  | 289 |  |  
			| Other |  |  | 5 |  |  |  | 6 |  |  |  | 6 |  |  |  | - |  |  
			| Software |  |  | 1-3 |  |  |  | 2,613 |  |  |  | 2,026 |  |  |  | 587 |  |  
			| Totals |  |  |  |  |  | $ | 10,860 |  |  | $ | 4,768 |  |  | $ | 6,092 |  |  
		
			|  |  | September 30, 2022 |  |  
			| (In thousands) |  | UsefulLife
 (Years)
 |  |  | Gross CarryingAmount
 |  |  | AccumulatedAmortization
 |  |  | Net Book ValueAmount
 |  |  
			| Customer relationships |  |  | 15 |  |  | $ | 4,833 |  |  | $ | 1,273 |  |  | $ | 3,559 |  |  
			| Certifications |  |  | 8 |  |  |  | 584 |  |  |  | 133 |  |  |  | 451 |  |  
			| Trademarks |  |  | 8-10 |  |  |  | 1,306 |  |  |  | 586 |  |  |  | 720 |  |  
			| Patents |  |  | 20 |  |  |  | 931 |  |  |  | 118 |  |  |  | 813 |  |  
			| Developed Technology |  |  | 10 |  |  |  | 295 |  |  |  | 5 |  |  |  | 290 |  |  
			| Other |  |  | 5 |  |  |  | 6 |  |  |  | 6 |  |  |  | - |  |  
			| Software |  |  | 1-3 |  |  |  | 2,452 |  |  |  | 1,909 |  |  |  | 543 |  |  
			| Totals |  |  |  |  |  | $ | 10,407 |  |  | $ | 4,030 |  |  | $ | 6,376 |  |  | 
| Schedule of Finite-Lived Intangible Assets, Future Amortization Expense [Table Text Block] | 
		
			| (In thousands) |  | Estimated amortizationexpense
 |  |  
			| FY 2024 |  | $ | 1,148 |  |  
			| FY 2025 |  |  | 698 |  |  
			| FY 2026 |  |  | 563 |  |  
			| FY 2027 |  |  | 469 |  |  
			| FY 2028 |  |  | 460 |  |  
			| Thereafter |  |  | 2,754 |  |  
			| Total |  | $ | 6,092 |  |  | 
| Schedule of Earnings Per Share, Basic and Diluted [Table Text Block] | 
		
			| Year ended September 30, (In thousands except share data) |  | 2023 |  |  | 2022 |  |  | 2021 |  |  
			| Net income |  | $ | 32,533 |  |  | $ | 49,362 |  |  | $ | 20,327 |  |  
			| Weighted average common shares |  |  | 14,975,972 |  |  |  | 13,771,665 |  |  |  | 13,720,699 |  |  
			| Dilutive potential common shares |  |  | 36,555 |  |  |  | 134,319 |  |  |  | 63,593 |  |  
			| Weighted average dilutive common shares outstanding |  |  | 15,012,527 |  |  |  | 13,905,984 |  |  |  | 13,784,294 |  |  
			| Earnings per share: |  |  |  |  |  |  |  |  |  |  |  |  |  
			| Basic |  | $ | 2.17 |  |  | $ | 3.58 |  |  | $ | 1.48 |  |  
			| Diluted |  | $ | 2.17 |  |  | $ | 3.55 |  |  | $ | 1.47 |  |  | 
| Useful Lives [Member] |  | 
| Notes Tables |  | 
| Property, Plant and Equipment [Table Text Block] | 
		
			|  |  | Years |  |  
			| Equipment |  |  | 3 – 15 |  |  
			| Leasehold improvements |  |  | 7-10 or life of lease |  |  
			| Vehicles |  |  | 3 |  |  
		
			| (In thousands) |  | September 30, 2023 |  |  | September 30, 2022 |  |  
			| Manufacturing equipment |  | $ | 23,580 |  |  | $ | 18,418 |  |  
			| Office equipment |  |  | 4,560 |  |  |  | 4,174 |  |  
			| Leasehold improvements |  |  | 6,107 |  |  |  | 5,000 |  |  
			| Vehicles |  |  | 446 |  |  |  | 340 |  |  
			| Construction in progress |  |  | 2,447 |  |  |  | 1,715 |  |  
			| Property, plant and equipment, gross |  |  | 37,140 |  |  |  | 29,647 |  |  
			| Less accumulated depreciation |  |  | 15,613 |  |  |  | 11,418 |  |  
			| Property, plant and equipment, net |  | $ | 21,527 |  |  | $ | 18,229 |  |  |