The story of GM3ITN's new 3ele monoband 20 metre Yagi.
We used a set of average sizes taken from 4 different 20 mtr yagi designs, albeit in a plumbers delight form.
My Amigo Jim GM3KBZ took the channel brackets to drill the holes to accomodate accurately the 4 U-bolts on each of the 3 channel brackets.
A 21 foot x 2" aluminium scaffold pole was given to me by neighbour Alan GM4TOQ and an hour was passed with steel wool brightening it up to match the shiny new elements.
After this was completed, the channel brackets were fitted to each end of the boom ie.the reflector and director, the clamp to fit the boom to the stub mast was placed 10 feet from one end next to the driven element channel bracket.Star washers were fitted to all the U-bolts for security reasons, slackening of these brackets was just not on in the high winds.
The 3 channel brackets were then
accurately lined up at 90 degrees to the stub mast clamp and marked director, driven and reflector,the elements were then assembled one by one and measured to the sizes and black plastic tape marking the 9" approximate distance each tube telescoped into each other.
The bottom of the boom ready to accept the reflector element
The construction was done in the following order, The Gamma match was tuned with the assistance of Jim GM3KBZ and it is 1:1 from 14350-14200khz and 1:1.3 14200-14000khz
"The DXTerminator" is a S.A.S. Copyright 2003
FIRST QSO WAS WITH DP0POL ON THE GERMAN ANTARCTIC BASE 599 FIRST CALL!!!!
After more than 10 years good use from a TB3 tribander having suffered the loss back in the 1980's of my 20 metre monoband 2 ele wide spaced Cubical Quad in over 100mph winds it was decided to go for a 3 ele Monoband Yagi with .2 spacing as the sunspot peak had passed and the MUF propagation drop was on.
The TB3 Yagi style had withstood the high winds of the past 10 winters with no damage what so ever.
The order for elements and hardware arrives from Sandpiper.
An order for the tubing, channelling, u-bolts and jubilee clips was sent to "Sandpiper Technology" and all the elements and hardware including the gamma match arrived promptly in a few days.They were made to "Clydebuilt" specifications, as they will be competing with the everpresent 100+ mph. winds that whirl in from the North Atlantic during the winter months.
A morning was spent cutting the narrow Vee into
the tubes
which had Jubilee clips and were deburred ready for fitting
The Gamma match
The coax choke with plug to go direct to gamma match
Work almost completed as the sun goes down
The finished article...GM3ITN's new "DXTerminator" nearly 8db gain and 30+db back to front, better than my old quad.
1.The pre assembled boom was fitted on the stub mast of the tilted over tower and the centre section of each element fitted.
2.The boom was rotated right and left enough for the director elements to be fitted.
3.The driven element was fitted by the same method and then the gamma match.
4.Lastly the reflector element was assembled only 1 foot from the ground.
Finally the beam was ready for the tune up
A 21'x 2" scaffold pole was used as the boom
