Channel Master Stereo Probe 9

The Channel Master Stereo Probe 9, model number 3025 (previously 4408), is a log-Yagi array with nine elements on a 138″ boom. Four folded dipole elements are driven.

I modeled the antenna with the AO 9.53 Antenna Optimizer program. This image shows the antenna geometry. Unlike other designs with multiple driven elements, the Probe 9 avoids inducing current in the boom by eliminating phasing-line crossover.

This shows segmentation detail for the phasing lines. Blue dots indicate analysis segments. The red dot is the feedpoint. The first phasing line bows inward to avoid the mast.

Ken Wetzel uses this Probe 9 at Ridgecrest, California.

Modeling Results

Calculated performance is for 28 analysis segments per conductor halfwave with additional segments for the first phasing line. Forward gain includes mismatch and conductor losses. F/R is the ratio of forward power to that of the worst backlobe in the rear half-plane.

Frequency  Impedance    SWR   Mismatch  Conductor   Forward    F/R
   MHz        ohms             Loss dB   Loss dB   Gain dBd     dB
    88     122 - j143   3.11     1.33      0.04      6.84     15.38
    89     151 - j64    2.10     0.59      0.04      7.91     17.75
    90     192 - j0     1.56     0.21      0.03      8.45     17.94
    91     242 + j47    1.32     0.08      0.02      8.66     18.12
    92     297 + j77    1.29     0.07      0.02      8.69     18.30
    93     352 + j86    1.36     0.10      0.02      8.66     18.52
    94     400 + j76    1.43     0.14      0.02      8.62     18.78
    95     434 + j48    1.48     0.17      0.01      8.60     19.08
    96     447 + j13    1.49     0.17      0.01      8.61     19.48
    97     436 - j19    1.46     0.15      0.01      8.66     19.95
    98     408 - j39    1.39     0.12      0.01      8.74     20.56
    99     372 - j41    1.28     0.07      0.01      8.86     21.25
   100     334 - j24    1.14     0.02      0.01      8.98     22.00
   101     303 + j7     1.03     0.00      0.01      9.08     22.23
   102     282 + j50    1.20     0.04      0.02      9.12     19.39
   103     272 + j102   1.45     0.15      0.02      9.06     17.15
   104     278 + j162   1.75     0.33      0.02      8.89     15.37
   105     305 + j225   2.07     0.56      0.02      8.62     13.98
   106     368 + j282   2.33     0.76      0.02      8.33     13.03
   107     480 + j296   2.42     0.82      0.02      8.10     12.54
   108     585 + j178   2.19     0.65      0.03      8.06     12.76

Antenna File

Probe 9
Free Space Symmetric
98 MHz
77 6063-T832 wires, inches
p1 = 0		; element positions
p2 = 20
p23 = 30
p3 = 40
p34 = 50
p4 = 60
p4f = 61.375	; feedpoint
p5 = 75
p6 = 90
p7 = 105
p8 = 120
p9 = 135
a1 = 27.25	; DE1 overall half-length
a2 = a1 - 1	; start of tip curve
a3 = a1 - 3	; end of 0.5"-diameter tubing
b1 = 31.75	; DE2
b2 = b1 - 1
b3 = b1 - 3
c1 = 34.25	; DE3
c2 = c1 - 1
c3 = c1 - 3
d1 = 37.25	; DE4
d2 = d1 - 1
d3 = d1 - 3
d = .375	; element diameter
c = .5		; folded dipole tip diameter
m = 1.75	; director mounting bracket half-width
b = 1		; equivalent diameter of mounting brackets
s = 1.125	; phasing-line spacing
t = .375	; phasing-line spacing near mast
h = 1.25	; folded dipole halfheight
j = h + .5	; rise at phasing-line joint between DE2 & DE3
shift x -67.5

1  p1     -d1  0    p1    -d2  h    c
1  p1     -d2  h    p1    -d3  h    c
1  p1     -d3  h    p1     -2  h    d
1  p1      -2  h    p1      2  h    b
1  p1       2  h    p1     d3  h    d
1  p1      d3  h    p1     d2  h    c
1  p1      d2  h    p1     d1  0    c
1  p1     -d1  0    p1    -d2 -h    c
1  p1     -d2 -h    p1    -d3 -h    c
1  p1     -d3 -h    p1     -s -h    d
1  p1       s -h    p1     d3 -h    d
1  p1      d3 -h    p1     d2 -h    c
1  p1      d2 -h    p1     d1  0    c

1  p2     -c1  0    p2    -c2  h    c
1  p2     -c2  h    p2    -c3  h    c
1  p2     -c3  h    p2     -s  h    d
1  p2       s  h    p2     c3  h    d
1  p2      c3  h    p2     c2  h    c
1  p2      c2  h    p2     c1  0    c
1  p2     -c1  0    p2    -c2 -h    c
1  p2     -c2 -h    p2    -c3 -h    c
1  p2     -c3 -h    p2     -s -h    d
1  p2       s -h    p2     c3 -h    d
1  p2      c3 -h    p2     c2 -h    c
1  p2      c2 -h    p2     c1  0    c

1  p3     -b1  0    p3    -b2  h    c
1  p3     -b2  h    p3    -b3  h    c
1  p3     -b3  h    p3     -s  h    d
1  p3       s  h    p3     b3  h    d
1  p3      b3  h    p3     b2  h    c
1  p3      b2  h    p3     b1  0    c
1  p3     -b1  0    p3    -b2 -h    c
1  p3     -b2 -h    p3    -b3 -h    c
1  p3     -b3 -h    p3     -s -h    d
1  p3       s -h    p3     b3 -h    d
1  p3      b3 -h    p3     b2 -h    c
1  p3      b2 -h    p3     b1  0    c

1  p4     -a1  0    p4    -a2  h    c
1  p4     -a2  h    p4    -a3  h    c
1  p4     -a3  h    p4     -s  h    d
1  p4      -s  h    p4f    -s  h    .5		; equiv diam = half the plate width
1  p4f     -s  h    p4f     s  h    #18 copper	; feedpoint
1  p4       s  h    p4f     s  h    .5		; equiv diam = half the plate width
1  p4       s  h    p4     a3  h    d
1  p4      a3  h    p4     a2  h    c
1  p4      a2  h    p4     a1  0    c
1  p4     -a1  0    p4    -a2 -h    c
1  p4     -a2 -h    p4    -a3 -h    c
1  p4     -a3 -h    p4     -s -h    d
1  p4       s -h    p4     a3 -h    d
1  p4      a3 -h    p4     a2 -h    c
1  p4      a2 -h    p4     a1  0    c

12 p4       s -h    p34     t -h    d		; higher segmentation to make
12 p34      t -h    p3      s -h    d		; segment length equal to
12 p4      -s -h    p34    -t -h    d		; phasing-line spacing
12 p34     -t -h    p3     -s -h    d

1  p3       s  h    p23     s  j    d
1  p23      s  j    p2      s  h    d
1  p3      -s  h    p23    -s  j    d
1  p23     -s  j    p2     -s  h    d

1  p2       s -h    p1      s -h   .25
1  p2      -s -h    p1     -s -h   .25

1  p5  -25    0    p5   -m    0    d
1  p5   -m    0    p5    m    0    b
1  p5    m    0    p5   25    0    d

1  p6  -24.5  0    p6   -m    0    d
1  p6   -m    0    p6    m    0    b
1  p6    m    0    p6   24.5  0    d

1  p7  -24.5  0    p7   -m    0    d
1  p7   -m    0    p7    m    0    b
1  p7    m    0    p7   24.5  0    d

1  p8  -24.5  0    p8   -m    0    d
1  p8   -m    0    p8    m    0    b
1  p8    m    0    p8   24.5  0    d

1  p9  -24    0    p9   -m    0    d
1  p9   -m    0    p9    m    0    b
1  p9    m    0    p9   24    0    d

1 source
Wire 42, center

Mounting bracket equivalent diameter calculated with the YO 7.66 Yagi Optimizer.

August 27, 201388108 MHz