AT1500CV Schematic
8
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8 Front Panel Description
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1. TUNE.
Dual section variable capacitor (960 &
65pf). Can be switched from output to input side of net-
work using switch # 4.
2. POWER/SWR METER.
Dual needle meter dis-
plays FORWARD and REFLECTED power in watts.
SWR is measured where the two needles intersect on
the red scale.
Metering works only if the unit is pro-
vided with 12VDC at the rear power jack.
3. Hi-Lo PASS.
Two position switch selects Low
Pass (High Z, capacitor on output side), and High Pass
(Low Z, capacitor on input side). The switching is per-
formed with a 40 amp contact relay.
This function
only works if the unit is provided with 12VDC at the
rear power jack.
4. Hi-Lo CAPACITOR.
Two position switch selects
the low value variable capacitor section of 65pf, or par-
allels the two sections for a total of 1025pf. The switch-
ing is performed with a 40 amp contact relay.
This
1
2
3
5
6
7
8
4
9
Operating Your BT1500A 13
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CAUTION: When approaching the end stops of the
roller inductors, SLOW DOWN. Running the rollers
too hard into the mechanical end stops on either end of
the inductors can damage them.
reading of 50-100 watts on the FORWARD scale. Adjust the
TUNE and INDUCTOR controls for a minimum REFLECTED
reading while maintaining a FORWARD reading of 50-100 watts
using your transmitter power control.
The TUNE control varies the capacitor and provide fine
adjustments. The INDUCTOR crank control provides coarse
adjustment.
7.
Read the SWR on the red scale at the point where the
two needles intersect. Repeat STEP 6 until the lowest SWR read-
ing is obtained. The SWR should be 2:1 or lower.
8.
When you have tuned your antenna to the best SWR, re-
cord the settings of the TUNE and INDUCTANCE controls on
the chart above for future reference. When you retune, use these
settings as your starting point.
Notes:
1.
An SWR of 1:1 is best, but an SWR as high as 2:1 may be
acceptable. Check your transmitter/amplifier manual for details.
2.
If you cannot get an acceptable SWR, lengthen or shorten
your antenna and/or feedlines and retune.
3.
Any time a new or different antenna is connected, it is nec-
essary to repeat the tuning procedure for each antenna.
4.
Once every 4-6 months clean the roller coil with 70% iso-
propyl alcohol and a clean cotton cloth. Do not transfer any of
the conducting grease on the rod that guides the roller wheel as
this will contaminate the windings on the roller coil body. All
points of rotation are factory lubricated and this is not required
by the user. All moving parts are factory lubricated with Lithium
grease only.
