FSL coil Q of 1162/46 and 660/46 (added 330/46) Litz compared using HP4342A Q meter

Steve Ratzlaff

I wound a coil using 330/46 Litz to compare with the other two. 21 turns gave 273.3 uH, quite a bit higher than the other two due to the narrower width coil. Probably 1 or 2 turns should be removed for use in an actual FSL with 385 pF tuning cap.

On 7/5/2020 3:46 PM, STEVE wrote:

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    330/46

1700 kHz  305Q        310Q     263Q

1600 kHz  345Q        350Q     300Q

1500 kHz  385Q        395Q     340Q

1400 kHz  440Q        445Q     380Q

1300 kHz  500Q        500Q     433Q

1200 kHz  565Q        570Q     490Q

1100 kHz  643Q        645Q     555Q

1000 kHz  740Q        730Q     630Q

900 kHz   840Q        835Q     710Q

800 kHz   955Q        930Q     785Q

700 kHz   1116Q       1084Q    860Q

600 kHz   1246Q       1144Q    910Q

550 kHz   1301Q       1173Q    925Q

520 kHz   1332Q       1186Q    925Q

510 kHz---------------1188Q    928Q (340 pF for 330/46)