FSL coil Q of 1162/46 and 660/46 Litz compared using HP4342A Q meter

Steve Ratzlaff

This experiment compares a ferrite sleeve coil of 1162/46 Litz with a ferrite sleeve coil of 660/46, both 21 turns with final coil diameter about 6 3/8", using 140 mm ferrite rods in the ferrite sleeve. The same ferrite sleeve was used for both coils, with the coils centered on the sleeve for peak inductance. The 1162/46 coil measured 236.5 uH; the 660/46 coil measured 253 uH for the same 21 turns for each. (The fatter Litz will have a little less inductance compared to the thinner Litz for the same number of turns due to being a wider coil.)

Each ferrite sleeve coil was suspended 7" above the Q meter deck, oriented horizontally; each coil had about 12" of pigtail length. The HP4342A Q meter capacitor (very high Q) was used to resonate each coil. Solid copper lugs were used on the ends of each coil to connect the coil to the Q meter. Coil Q should directly relate to signal level coupled to the receiver with higher Q giving higher signal level. Since the Q meter's variable capacitor was used, which has much higher Q than any external variable capacitor I'm aware of, this removes the external capacitor Q effects from the experimental results, only comparing the two Litz types.


Steve AA7U

                            1162/46    660/46

1700 kHz  305Q        310Q

1600 kHz  345Q        350Q

1500 kHz  385Q        395Q

1400 kHz  440Q        445Q

1300 kHz  500Q        500Q

1200 kHz  565Q        570Q

1100 kHz  643Q        645Q  Q's are equal at this frequency

1000 kHz  740Q        730Q  Fatter Litz begins to have better Q

900 kHz   840Q        835Q

800 kHz   955Q        930Q

700 kHz   1116Q       1084Q

600 kHz   1246Q       1144Q

550 kHz   1301Q       1173Q

520 kHz   1332Q       1186Q

1162/46 Litz--385 pF, 516 kHz, 1333Q (max capacitance of variable cap Gary uses)

510 kHz               1188Q

660/46 Litz--385 pF, 502 kHz, 1189Q (max capacitance of variable cap Gary uses)

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