---------------
FIDO MESSAGE AREA==> TOPIC: 188 HAM TECH Ref: E3H00002 Date: 03/12/97
From: STAN BLACK Time: 09:55am
\/To: WAYNE SAROSI (Read 3 times)
Subj: Re: reruns
Yes! Very definately yes!! Thanks again for the LPDA plans!! 73 de Stan
kc5bfa
--- GEcho/386 1.11+
* Origin: Great Beta Video System For Sale, Includes Movie (1:392/11)
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FIDO MESSAGE AREA==> TOPIC: 188 HAM TECH Ref: E3H00003 Date: 03/13/97
From: CHARLES MCCURDY Time: 01:18am
\/To: RAY BROWN KB0STN (Read 3 times)
Subj: re: ten-tec 6mtr
Hi i see what i did wrong i didnt read the part on installing the wires i
just looked at the picture how ther suppose to go i got some more wire ill
try if not ill make a run to radio shack.
but if yours dose not transmite could it be the c1970 or c1971 transisters
test them out with a volt tester all so look at the board real good check for
cold solder joints.
hope that helps.
73s kc5cxu
--- Maximus 2.02
* Origin: The Dx Board (1:106/1492)
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FIDO MESSAGE AREA==> TOPIC: 188 HAM TECH Ref: E3H00004 Date: 03/12/97
From: DAVID LAWSON Time: 02:14pm
\/To: ALL (Read 3 times)
Subj: Alinco 130
Does anyone have any experience with the Alinco DR-130? I just picked one up
at a HamFest and man it runs hot enough to fry a piece of bacon; even on low
power. Its not a power problem. Im running off a deep cycle. Apparently it is
not an isolated problem because I have talked to 2 others who have the same
prob. One of them had to send it for a warranty fix because it burnt it up. A
three inch fan keeps it cool, but this thing worries me.
kf4ebp
--- Maximus 3.01
* Origin: The AmaRad BBS (1:362/1110)
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FIDO MESSAGE AREA==> TOPIC: 188 HAM TECH Ref: E3H00005 Date: 03/09/97
From: ROY WITT Time: 09:19am
\/To: WAYNE SAROSI (Read 3 times)
Subj: LPDA.DOC
=== Begin LPDA.DOC ===
LPDA.BAS 03/13/87
This program is used to design log-periodic dipole arrays. The design
procedure used is a combination of that presented in the ARRL Antenna
Book, Fourteenth Edition, pp 6-24 through 6-26, and the corrections
discussed in the Technical Correspondence column of QST for October,
1986, p 51. Reference to the Antenna Book is required in order to get
the full benefit of the program. However, simply selecting a
frequency range and allowing all other values to default to their
initial values will produce a workable LPDA design with about 8.5 dB
gain (according to Fig. 59 in the Antenna Book).
SELECTION OF PARAMETERS
It is usually wise to select a frequency range slightly wider than the
desired one. Reducing the lowest frequency by about 5% from the
actual lowest frequency of operation and increasing the highest
frequency by about 5% should do the trick. This is done because the
SWR of the array tends to increase at the ends of the design range.
The tau and sigma parameters affect the gain, boom length and number
of elements of the array. The usual procedure is to use the default
tau and sigma to start with, then adjust them for the desired boom
length and number of elements, accepting whatever gain you get.
(Mechanical construction considerations seem to take precedence over
getting that last half dB of gain!) Tau and sigma are used to
calculate alpha, the array half-angle. The program lets you adjust
alpha as an alternative to adjusting sigma. I find it easier to
visualize the effect on the array size of adjusting alpha than of
adjusting sigma. There are no hard and fast rules here. The program
specifies minimum and maximum values, and as long as you stay within
these you'll be OK. The gain you'll get can be determined using the
final tau and sigma values on the chart in Fig. 59 of the Antenna
Book.
All feeder calculations are made assuming round conductors (wire or
tubing). Spacing is center-to-center. Note that the default R0
(feed-point impedance) is 200. This is based on the assumption that a
4:1 balun will be used to feed the array from 50-ohm coax. Direct 50-
ohm feed is often not possible. (Sometimes it will result in a
conductor spacing smaller than the conductor diameter, a physical
impossibility in this universe.) If the design bandwidth of the array
is fairly small (single band), another possible approach is to design
the array for a 104-ohm R0 and use a 1/4-wave matching section of 72-
ohm coax between the feedpoint and the 50-ohm feedline. In any case,
select the element feeder diameters based on mechanical
considerations. The required feeder spacing is then calculated by the
program. You can then specify the actual spacing you will use, and
the program will calculate how the difference between the actual
spacing and the calculated will affect the input impedance of the
array.
The Antenna Book shows a terminating stub at the back of the array.
It is not clear that this performs any useful function, although
experimentation may be in order. At least one 2-meter array
constructed in the ARRL lab by K1TD exhibited the expected
characteristics with the end of the feeder left unterminated (open).
I'd like to hear from anyone who develops further information,
experimental or theoretical, on this point.
GL de KE3Z
SAMPLE RUN:
Log-periodic dipole array calculations
Enter lowest frequency: 13
Enter highest frequency: 32
Enter TAU, 0.8 <= TAU < 1.0 (default .9 ):
Enter SIGMA, 0.05 <= SIGMA < .1662 (default .05 ):
Frequency: 13 to 32
Operating BW: 2.461538
Array BW: 1.254
Structure BW: 3.086769
TAU: .9
SIGMA: .05
ALPHA: 26.56505
Boom length: 25 ft 7.02 in (307.02 in)
Number of elements: 11.69781
Longest element: 37 ft 10.15 in (454.15 in)
Max. stub length: 9 ft 5.53 in (113.53 in)
Change T)au, S)igma, A)lpha or F)requency
calculate X)msn line or <return> for element data?
Frequency: 13 to 32
Operating BW: 2.461538
Array BW: 1.254
Structure BW: 3.086769
TAU: .9
SIGMA: .05
ALPHA: 26.56505
Boom length: 25 ft 7.02 in (307.02 in)
Number of elements: 11.69781
Longest element: 37 ft 10.15 in (454.15 in)
Max. stub length: 9 ft 5.53 in (113.53 in)
El. Length Spacing
1 37 ft 10.15 in (454.15 in) ---
2 34 ft .73 in (408.73 in) 3 ft 9.41 in (45.41 in)
3 30 ft 7.86 in (367.86 in) 3 ft 4.87 in (40.87 in)
4 27 ft 7.07 in (331.07 in) 3 ft .78 in (36.78 in)
5 24 ft 9.97 in (297.97 in) 2 ft 9.1 in (33.1 in)
6 22 ft 4.17 in (268.17 in) 2 ft 5.79 in (29.79 in)
7 20 ft 1.35 in (241.35 in) 2 ft 2.81 in (26.81 in)
8 18 ft 1.22 in (217.22 in) 2 ft .13 in (24.13 in)
9 16 ft 3.49 in (195.49 in) 1 ft 9.72 in (21.72 in)
10 14 ft 7.94 in (175.94 in) 1 ft 7.54 in (19.54 in)
11 13 ft 2.35 in (158.35 in) 1 ft 5.59 in (17.59 in)
12 11 ft 10.51 in (142.51 in) 1 ft 3.83 in (15.83 in)
Change T)au, S)igma, A)lpha or F)requency
calculate X)msn line or <return> for element data?x
Enter desired R0 (default 200 ):
Enter element dia. in inches (default .125 ):
Enter feeder wire dia. in inches (default .125 ):
Enter actual feeder spacing in inches (default = 2.140283 ): 2
Required feeder spacing: 2.140283 in. Actual: 2 in.
Required feeder Z0: 423.5471 Actual: 415.4214
Desired R0: 200 Actual: 197.6417
SWR: 1.011932
Frequency: 13 to 32
Operating BW: 2.461538
Array BW: 1.254
Structure BW: 3.086769
TAU: .9
SIGMA: .05
ALPHA: 26.56505
Boom length: 25 ft 7.02 in (307.02 in)
Number of elements: 11.69781
Longest element: 37 ft 10.15 in (454.15 in)
Max. stub length: 9 ft 5.53 in (113.53 in)
Change T)au, S)igma, A)lpha or F)requency
calculate X)msn line or <return> for element data?
=== End LPDA.DOC ===
Roy
... 2,000,000 Extra Class Lemmings can't be wrong.
* Origin: KB6PI's Antenna Farm * San Diego, CA (1:202/909.10)
---------------
FIDO MESSAGE AREA==> TOPIC: 188 HAM TECH Ref: E3H00006 Date: 03/09/97
From: ROY WITT Time: 09:20am
\/To: WAYNE SAROSI (Read 3 times)
Subj: LPDA2.BAS
=== Begin LPDA2.BAS ===
10 REM LOG PERIODIC DIPOLE ARRAY PROGRAM
20 REM "ANTENNA DESIGN USING PERSONAL COMPUTERS"
30 DATA .139,.782,.147,.822,.157,.865,.163,.892,.168,.916,.172,.928
40 DATA .174,.940,.176,.950,.178,.964
50 DIM SIG(9),TAU(9)
60 REM FILL ARRAYS
70 FOR I=1 TO 9
80 READ SIG(I),TAU(I)
90 NEXT I
100 PI=3.141593
110 KEY OFF
120 CLS
130 COLOR 1,0
140 PRINT "LOG-PERIODIC ARRAY DESIGN"
150 COLOR 4,0
160 PRINT
170 INPUT "WHAT IS THE LOWER FREQUENCY(MHz)";FMIN
180 INPUT "WHAT IS THE UPPER FREQUENCY(MHz)";FMAX
190 INPUT "WHAT IS THE DESIRED GAIN(dB)(BETWEEN 8 AND 12)";D0
200 IF D0<8 OR D0>12 THEN GOTO 190
210 INPUT "WHAT IS THE RADIUS OF THE LARGEST DIPOLE(meters)";A1
220 COLOR 14,0
230 REM INTERPOLATE TO FIND SIGMA, TAU
240 I1%=2*D0-15
250 IF I1%<1 THEN I1%=1
260 IF I1%>9 THEN I1%=9
270 I2%=I1%+1
280 IF I2%>9 THEN I2%=9
290 DI=(I1%+15)/2
300 S=SIG(I1%)+2*(D0-DI)*(SIG(I2%)-SIG(I1%))
310 T=TAU(I1%)+2*(D0-DI)*(TAU(I2%)-TAU(I1%))
320 PRINT
330 PRINT "SIGMA,TAU=",S,T
340 ALP=ATN((1-T)/(4*S))
350 XL=300/FMIN
360 LOD=.25*XL/A1
370 F=LOD/(1+LOD)
380 DO=0
390 AO=A1
400 LO=.48*F*XL
410 XL=300/FMAX
420 LMIN=.48*XL
430 I=0
440 PRINT "DIPOLE # SPACING LENGTH RADIUS"
450 I=I+1
460 PRINT USING " ## ##.#### ##.#### .####";I,DO,LO,AO
470 IF LO<LMIN THEN GOTO 520
480 DO=2*S*LO
490 LO=T*LO
500 AO=LO*.5/LOD
510 GOTO 450
520 PRINT
530 COLOR 4,0
540 INPUT "CONTINUE(Y,N)";IS$
550 IF IS$<>"N" THEN GOTO 120
560 COLOR 7,0
570 KEY ON
580 END
=== End LPDA2.BAS ===
... Hey, you dropped your pen. Uh, while you're down there!
* Origin: KB6PI's Antenna Farm * San Diego, CA (1:202/909.10)
---------------
FIDO MESSAGE AREA==> TOPIC: 188 HAM TECH Ref: E3H00007 Date: 03/09/97
From: ROY WITT Time: 09:23am
\/To: WAYNE SAROSI (Read 3 times)
Subj: LPDA Basic Program
Hello Wayne.
I found the program I used to model the TV LPDA that I made. I don't recall
or have the plans that I made it with, but as the owner of a machine shop, I
dont' have a problem making what I need.
From memory, the boom spacing (1/2"dia alum) was about 1.25" or so. The
overall length is around 4'.
--------------------------------------------------------
| 0 0 |
-------------------------------------------------------- -------
| | |
| | |
| Insulator | typical three places 1.25
| | |
| | |
-------------------------------------------------------- -------
| 0 0 |
--------------------------------------------------------
See next message for the Basic programs.
... Keep your frequency up, that way you won't lose your load.
* Origin: KB6PI's Antenna Farm * San Diego, CA (1:202/909)