Maco Antennas M108HV Assembly Instructions Manual - page 8
*
THESE DIMENSONS ARE APPROXIMATE.
REFER TO THE INSTRUCTIONS ON
THE
S.W.R. TO DETERMINE EXACT SETTINGS. THERE
ARE2 SEPARATEGAMMA ADJUSTMENTS, 1. CAPACI-
TOR ADJUSTMENT, 2. SLIDER POSITION.
DO NOT MOVE BOTH AT THE SAME TIME. MOVE
THE CAPACITOR FIRST, THEN, IF NECESSARY MOVE
THE SLIDER. AND GO BACK TO THE CAPACITOR.
N 1 2 - 7
DRIVEN
\
ELEMENT
LK.
NUTS
GAMMA STRAPS
(SLIDER)
2 4 N U T \
I
S T A R - e - (
W A S H E R
CABLE
(CUSTOMER
FURNISHED)
N12
x
SCREWS
LK. WSHRS & SQ.
-
PLASTIC SHOULDER
WASHER
FLATWASHER
GO1 P GAMMA MATCH
FIGURE 4
GAMMA MATCH MOUNTING
Mount the gamma match
to the driven element, using the gamma straps (202,
and attaching
hardware as shown. Attach your 52 ohm coaxial cable to the connector (S42) and dress along boom and down the
mast. The gamma is shown pointing down this is to let water out.
ADJUSTING THE STANDING WAVE RATIO
Refer to Figure 4. The dimensions given are approximate and should be used as a starting point. * The gamma
match has 2 adjustments. First is the capacitor adjust and second is the slider adjust. Connect a SWR bridge coax
between your transmitter and the antenna and check the SWR. If adjustment is required, loosen the clamp on the
gamma match and the screws holding the slider (gamma straps (202)). Next move the capacitor adjustment first one
direction, then the other until a minimum SWR reading is obtained. If SWR is not yet satisfactory, move the slider
out 2” away from the boom.
reading has gone up move the slider
the original position and
towards
the boom. Now readjust the capacitor for minimum SWR. You should now be able to determine which direction to
move the slider. Repeat the above procedure moving the slider in smaller increments until a satisfactory SWR is
obtained. Tighten all hardware. Disconnect the SWR bridge and reconnect your coaxial cable.
NOTE!
When assembling for vertical use, set antenna on a pole about 8 to 9 feet above the ground horizontally and
adjust SWR to 1.7. When you turn the antenna vertical and mount it on the tower, etc., the SWR will drop to 1.4 to
1.5. This is good; QUIT! Antenna results best if vertical antenna clears the top of the tower.
7