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TOROIDAL
FERRITE CORE TYPES
Recommended
core types for various frequency bands and power levels.
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Summary of
suitable ferrite cores and core types for a frequency range of 100
kHz to 50 MHz for power levels of 50W, 100W, and 500W continuous and
SSB. It assumes good thermal management and proper balun design.
Type 43 is
versatile for HF but heats up quickly at higher frequencies.
Type 61 is
ideal for upper HF and VHF, with lower losses at higher frequencies.
Average
Power: SSB power is typically 25-30% of PEP, allowing smaller cores
or fewer stacked cores to handle the same PEP compared to continuous
modes.
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Frequency
Range
|
CW
Power
|
SSB
Power
|
Core
Type
|
Recommended
Core(s)
|
Notes
|
|
100
kHz–1.5 MHz
|
50W
|
150w
|
Type
31
|
FT-140-31
|
Type
31 is best for low frequencies due to lower core losses.
|
|
100W
|
300w
|
Type
31
|
FT-240-31
|
Larger
core ensures better heat dissipation for higher power.
|
|
500W
|
1500w
|
Type
31
|
2 ×
FT-240-31
|
Stacked
cores improve power handling. Ensure proper cooling.
|
|
500W
|
1500w
|
Type
75
|
2 ×
FT-240-75
|
Type
75 is optimized for lower frequencies, but larger cores may be
needed for high power.
|
|
1.5–10
MHz
|
50W
|
150w
|
Type
43
|
FT-140-43
|
Type
43 is sufficient for moderate power with proper ventilation.
|
|
100W
|
300w
|
Type
43
|
FT-240-43
|
Handles
most HF applications at this power level.
|
|
500W
|
1500w
|
Type
43
|
2 ×
FT-240-43
|
Requires
cooling for continuous duty cycles.
|
|
500W
|
1500w
|
Type
61
|
2 ×
FT-240-61
|
Type
61 offers better performance for higher frequencies within
this range.
|
|
10–20
MHz
|
50W
|
150w
|
Type
43
|
FT-140-43
|
Adequate
for low power, but heat buildup limits performance.
|
|
100W
|
300w
|
Type
43
|
FT-240-43
|
Effective
for low to moderate power levels.
|
|
500W
|
1500w
|
Type
43
|
2 ×
FT-240-43
|
Requires
active cooling for high power.
|
|
500W
|
1500w
|
Type
61
|
2 ×
FT-240-61
|
Preferred
for higher frequencies within this range.
|
|
20–30
MHz
|
50W
|
150w
|
Type
43
|
FT-140-43
|
Limited
performance at the upper HF band. Upgrade to Type 61 for
efficiency.
|
|
100W
|
300w
|
Type
43
|
FT-240-43
|
Works
well for most HF applications.
|
|
500W
|
1500w
|
Type
43
|
3 ×
FT-240-43
|
Higher
core count manages heat from increased losses.
|
|
500W
|
1500w
|
Type
61
|
3 ×
FT-240-61
|
Better
efficiency at upper HF frequencies; good for continuous duty.
|
|
50
MHz (VHF)
|
50W
|
150w
|
Type
61
|
FT-140-61
|
Type
61 is ideal for VHF with low core losses.
|
|
100W
|
300w
|
Type
61
|
FT-240-61
|
Larger
core ensures higher power handling at VHF.
|
|
500W
|
1500w
|
Type
61
|
3 ×
FT-240-61
|
Stacked
cores reduce heating; active cooling recommended.
|
|
500W
|
1500w
|
Type
31
|
3 ×
FT-240-31
|
Type
31 can be used, but core losses will be higher at VHF compared
to Type 61.
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Efficiency
Comparison at 50 MHz
A Type 61
balun can achieve 90–95% efficiency at 50 MHz, while a Type 43
balun may only reach 50–70% due to core losses and heat
dissipation. The difference becomes more pronounced at higher power
levels.
| Parameter |
Type
43 Core |
Type
61 Core |
| Operating
Frequency Range |
~1 MHz
to ~30 MHz |
~10
MHz to ~200 MHz |
| Core
Losses |
High
(inefficient at 50 MHz) |
Low
(efficient at 50 MHz) |
| Efficiency
(%) |
~50–70%
(varies with power) |
~90–95% |
| Power
Handling |
Lower
due to heating |
Higher
due to lower losses |
| Heat
Generation |
Significant
at moderate power |
Minimal
at moderate power |
| Bandwidth |
Narrow
at 50 MHz (reactive losses dominate) |
Wide
at 50 MHz |
Data
Source: ChatGPT 4.0
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Page initiated 09
December, 2024
Page
last revised 05 November, 2025
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