Segment and Revenue Information - Schedule of Reportable Segment (Details) - USD ($) $ in Thousands	12 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2019
Segment Reporting Information [Line Items]
Revenue	$ 158,444	$ 110,128	$ 87,265
Gross profit	61,488	35,582	15,089
R&D expense	17,448	20,269	19,443
Unallocated operating expense
Selling, general, and administrative	24,544	24,631	32,080
Loss (gain) on sale of assets	515	(2,284)	(302)
Total unallocated operating expense	25,059	22,347	31,778
Operating income (loss)	18,981	(7,034)	(36,132)
Operating Segments
Segment Reporting Information [Line Items]
Revenue	158,444	110,128	87,265
Segment income (loss)	44,040	15,313	(4,354)
Aerospace and Defense | Operating Segments
Segment Reporting Information [Line Items]
Revenue	50,838	55,240	33,086
Gross profit	13,705	16,729	9,207
R&D expense	14,616	17,469	10,448
Segment income (loss)	(911)	(740)	(1,241)
Broadband | Operating Segments
Segment Reporting Information [Line Items]
Revenue	107,606	54,888	54,179
Gross profit	47,783	18,853	5,882
R&D expense	2,832	2,800	8,995
Segment income (loss)	$ 44,951	$ 16,053	$ (3,113)