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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.

73,

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)


Steve Ratzlaff
 

I should add that my 140mm ferrite rods are Chinese rods, not Russian rods, and that the results may be different using Russian rods. I don't have enough Russian rods to do the experiment using them. Gary's latest 6" FSL with Russian rods used 19 turns of the 1162/46 Litz where mine used 21 turns.

Steve AA7U

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.

73,

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)


Gary DeBock
 

Hi Steve,

Thanks for running these detailed "Q" tests between the 1162/46 and 660/46 Liz wire at various frequencies with the HP4342A Q meter. This kind of detailed test is something which would not be my first choice for using up my hobby time, but I'm happy that somebody did it! :-)

The 1162/46 Litz wire's 'Q" advantage on the low band covers the frequencies which are typically checked first during DXpeditions and band scans, so its substitution for the 660/46 Litz wire in 2014 may have given the impression that it was superior throughout the MW range, which apparently isn't so. But to be honest the recent replacement of the old "N50 365P" variable caps with the newer "N50 384P"variable caps seemed to provide a higher "Q" boost in the newer FSL's  than the switch in Litz wire, to the extent that it was the inspiration for the miniature "Frequent Flyer' FSL's which have tracked down long range DX in Hawaii and the Cook Islands.

To make matters even more interesting, Oren Elliott seems to have recently improved his manufacturing process in the later "N50 384P" variable caps, so that the N50 384P caps with a "0219" series number are clearly superior to those with a "0217" series number. I don't know if he has been improving the dielectric, rotor or stator, but these newest variable caps are extremely sharp performers-- to the extent that every FSL antenna heading for the Rockwork Cliff this summer will have one of the latest variable cap upgrades. With Hawaii and all overseas travel temporarily scratched out because of the Pandemic, the Rockwork cliff should be a dream DXing venue for both Tom R. and yours truly, who both broke our records for South Pacific NDB-DX last August. Tom told me that he's still uncovering new South Pacific NDB-DX from that trip, in addition to his record-breaking haul already posted.

Gary
 


Steve Ratzlaff
 

I just checked with Mike at https://www.mikeselectronicparts.com/ and he says his current caps are the latest version "0219" so I just ordered one to try.

Thanks for this info, Gary.

73,

Steve

On 7/5/2020 11:05 PM, Gary DeBock via groups.io wrote:
Hi Steve,
To make matters even more interesting, Oren Elliott seems to have recently improved his manufacturing process in the later "N50 384P" variable caps, so that the N50 384P caps with a "0219" series number are clearly superior to those with a "0217" series number. I don't know if he has been improving the dielectric, rotor or stator, but these newest variable caps are extremely sharp performers-- to the extent that every FSL antenna heading for the Rockwork Cliff this summer will have one of the latest variable cap upgrades.

Gary