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RF Cafe began life in 1996 as "RF Tools" in an AOL screen name web space totaling 2 MB. Its primary purpose was to provide me with ready access to commonly needed formulas and reference material while performing my work as an RF system and circuit design engineer. The World Wide Web (Internet) was largely an unknown entity at the time and bandwidth was a scarce commodity. Dial-up modems blazed along at 14.4 kbps while typing up your telephone line, and a nice lady's voice announced "You've Got Mail" when a new message arrived...

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Exodus Advanced Communications Best in Class RF Amplifier SSPAs

Toroids: Powdered Iron

Use the table below to calculate inductance and number of turns per the following formulas.

Where:

L = inductance in µH
A_L = µH per 100 turns
N = number of full turns

A_L Values
	Mix Type
Size	26	3	15	1	2	7	6	10	12	17	0
T-12	n/a	60	50	48	20	18	17	12	7.5	7.5	3.0
T-16	145	61	55	44	22	n/a	19	13	8.0	8.0	3.0
T-20	180	76	55	52	27	24	22	16	10	10	3.5
T-25	235	100	85	70	34	29	27	19	12	12	4.5
T-30	325	140	93	85	43	37	36	25	16	16	6.0
T-37	275	120	90	80	40	32	30	25	15	15	4.9
T-44	360	180	160	105	52	46	42	33	18.5	18.5	6.5
T-50	320	175	135	100	49	43	40	31	18	18	6.4
T-68	420	195	180	115	57	52	47	32	21	21	7.5
T-80	450	180	170	115	55	50	45	32	22	22	8.5
T-94	590	248	200	160	84	n/a	70	58	32	n/a	10.6
T-106	900	450	345	325	135	133	116	n/a	n/a	n/a	19
T-130	785	3350	250	200	110	103	96	n/a	n/a	n/a	15
T-157	870	420	360	320	140	n/a	115	n/a	n/a	n/a	n/a
T-184	1640	720	n/a	500	240	n/a	195	n/a	n/a	n/a	n/a
T-200	895	425	n/a	250	120	105	100	n/a	n/a	n/a	n/a

Iron Powder Magnetic Core Properties
Mix	Color	Material	μ	Temp Stability (ppm/°C)	f (MHz)	Uses
26	Yellow/White	Hydrogen Reduced	75	825	DC -1	EMI filters, DC chokes
3	Gray	Carbonyl HP	35	370	0.05 - 0.50	Exc. stability, good Q at low freq.
15	Red/White	Carbonyl GS6	25	190	0.10 - 2	Exc. stability, good Q
1	Blue	Carbonyl C	20	280	0.50 - 5	Exc. stability, good Q at low freq.
2	Red	Carbonyl E	10	95	2 -30	High Q
7	White	Carbonyl TH	9	30	3 - 35	Similar to mix 2 and mix 6, exc. temp stability
6	Yellow	Carbonyl SF	8	35	10 -50	Very good Q and temp. stability for 20-50 MHz
10	Black	Powdered Iron W	6	150	30 - 100	Good Q and stability for 40-100 MHz
12	Green/White	Synthetic Oxide	4	170	50 - 200	Good Q, moderate temp. stability
17	Blue/Yellow	Carbonyl	4	50	40 - 180	Similar to mix 12, better temp. stability, Q drops about 10% above 50 MHz, 20% above 100 MHz
0	Tan	Phenolic	1	0	100 - 300	L varies greatly with winding technique

Iron Powder Magnetic Core Dimensions
Size	Color	Dimensions (in)
Size	Color	O.D.	I.D.	Height
T-200-2	Red	2.00	1.25	0.55
T-94-2	Red	0.94	0.56	0.31
T-80-2	Red	0.80	0.50	0.25
T-68-2	Red	0.68	0.37	0.19
T-50-2	Red	0.50	0.30	0.19
T-37-2	Red	0.37	0.21	0.12
T-25-2	Red	0.25	0.12	0.09
T-12-2	Red	0.125	0.06	0.05
T-50-10	Black	0.50	0.30	0.19
T-37-10	Black	0.37	0.21	0.12
T-25-10	Black	0.25	0.12	0.09
T-12-10	Black	0.125	0.06	0.05
T-94-9	Yellow	0.94	0.56	0.31
T-80-6	Yellow	0.80	0.50	0.25
T-68-6	Yellow	0.68	0.37	0.19
T-50-6	Yellow	0.50	0.30	0.19
T-26-6	Yellow	0.25	0.12	0.09
T-12-6	Yellow	0.125	0.06	0.05

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