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Tech Notes

Directive Systems and Engineering will post application notes and updates as time permits. Click names below to open or download file/presentation.

BUILDING THE SUPER ROVER  As presented at the VHF Super Conference and the Dayton Hamvention.
WHAT ARE POWER DIVIDERS AND PHASING LINES AND HOW ARE THEY USED?  When you want to stack antennas for higher gain/sharper pattern, the antennas must be fed in phase for the two signals to add properly. 
LARCAN HI BAND SSPA CONVERSION to 222 MHz  As presented at the 2013 CSVHF conference in Chicago.
     – Larcan Power Supply Schematic
     – Larcan Power Supply Board Layout
     – Larcan items Directive Systems can Supply
T-MATCH TUNING NOTES  A discussion of the finer points of T-Match adjusting.
STACKING LOOP YAGIS  Explanation of how to get the phasing correct when stacking a pair of loop yagis side by side or one over top of the other . . . also when stacking 4 loop Yagis.
EFFECT of COAXIAL CABLES at HIGHER FREQUENCIES  Tips on interpreting VSWR curves at microwaves.
HOW to PLAN the INSTALLATION of MULTIPLE VHF ANTENNAS on ONE MAST  Plan your next multi-band setup!
SWR to RETURN LOSS CHART   Useful information!
50 MHz 4 YAGI CONTESTING ARRAY   2008 presentation at the Northeast and Southeast VHF Conferences. An update of an older design! (see below)
50 MHz 4 YAGI ANTENNA STACK  1989 Packrats VHF Conference presentation outlining details of the first switchable 50 MHz stack system.
This is a conference presentation given at a Pack Rats VHF Conference in 1989. The material is a little old, but there are some good ideas on assembling a multiple Yagi array with switching combination diagrams and a discussion of the benefits of a multiple antenna stack on 50 MHz. The basic idea is the same as used today in our 50 MHz contest station. The antennas have changed, but the basic switching idea remains.
MAGNETOMETER for AURORAL DETECTION   This is not antenna related, but is a great way to detect auroras!
(As told by Dave Olean) We had this magnetometer set up in the shipping area of the shop. It worked very well, with the sensor buried out in the garden. The UPS guy thought we were nuts! Everyday he would come in, look at the running chart that was set up in the shipping area, with the Earth’s magnetic field displayed, then look at me and shake his head. I’ll bet he told stories (at our expense) over at Skip’s Bar, on Friday nights!! This is a great project for all you propeller heads who want to detect auroras and then work DX on VHF!!