More BPF Measurements

I did some more random measurements on my BPF today as I was not happy with the earlier results. Although previously I had tuned all the coils such that a definite band pass was obtained for each of the bands, the insertion loss in most cases seemed to be higher than I had expected, As the tuning of the coils had remained untouched I decided to repeat some of the measurements on the higher bands again but with the BPF reversed. To my surprise with the noteable exception of the 12 and 10 Meter Bands the results in brackets shown as (*) for comparative purposes were quite different. Two thoughts came to mind, had I made an error whilst reading the range setting on one of the channels on my oscilloscope whilst taking some of the previous measurements (10 mV/cm rather than 20 mV/cm which would make an immediate difference of 6 dB) or is my tuning technique somehow to blame. So I need to take a deep breath and think about this some more and perhaps repeat all the measurements again before I start altering any core settings.

80 Meter Band
 KHz       Vin mV pp   Vout mV pp  Loss dB
3,500            720                230           9.9
3,600            590                300           5.8
3,700            550                320           4.7
3,800            660                230           9.1

40 Meter Band
 KHz       Vin mV pp   Vout mV pp  Loss dB
7,000            800                250         10.2
7,100            710                320           6.9
7,200            680                320           6.6
7,300            760                240           9.9

30 Meter Band
 KHz       Vin mV pp   Vout mV pp  Loss dB
10,000          800                190         12.4
10,100          630                210           9.6
10,200          570                130         12.8

20 Meter Band
 KHz       Vin mV pp   Vout mV pp  Loss dB
13,900        (1100)           (270)          (12)
14,000     860 (1060)   510 (340)    4.6 (9.9)
14,100     790 (980)     600 (430)    2.4 (7.1)
14,200     800 (940)     620 (510)    2.2 (5.4)
14,300     860 (1000)   550 (460)    3.9 (6.7)
14,400     900 (1060)   450 (350)    6.0 (9.6)
14,500        (1100)           (260)        (12.4)

17 Meter Band
 KHz       Vin mV pp   Vout mV pp  Loss dB
17,900        (1040)           (170)        (15.9)
18,000     580 (960)     380 (220)   3.6 (12.8)
18,100     640 (960)     360 (210)   5.0 (13.2)
18,200     660 (1000)   300 (160)   6.9 (15.9)

15 Meter Band
 KHz       Vin mV pp   Vout mV pp  Loss dB
21,000     480 (880)    190 (130)   8.0 (16.5)
21,100     430 (880)    230 (130)   5.5 (16.5)
21,200     440 (760)    250 (190)   4.9 (12)
21,300     480 (760)    240 (170)   6.0 (13.2)
21,400     500 (820)    200 (140)   8.0 (15.4)
21.500     480 (840)    160 (110)   9.6 (17.7)

12 Meter Band
KHz       Vin mV pp   Vout mV pp  Loss dB
24,800     280 (260)    195 (190)    3.1 (2.7)
24,900     290 (240)    200 (190)    3.2 (2)
25,000     275 (260)    205 (190)    2.5 (2.7)
25,100     350                190          5.4

10 Meter Band
 KHz       Vin mV pp   Vout mV pp  Loss dB
28,000           325                150          6.7
28,500           215                190          1.1
28,700          (250)              (210)       (1.5)
29,000           270                215          1.9
29,500           365                180          6.2
29,700           365                150          7.7