--------------- 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) --------------- 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) --------------- 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) --------------- 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 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 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 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"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)