Operation - Autek Research WM-1 SWR Instructions Manual

Your new WHl SWR wattmeter has been thoroughly tested
t wlce before shipment. Please read the instructions
carefully for besc resultt , and a ave them f or future
reference.
A. POWER
The WH1 needs +9 to +18 vdo at approximately 15 ma.
Plug the 115 vac adaptor into the jac~ at the left rear.
The WH1 may also be powered frora a battery. A 9 volt
batt ery ls marginal , but usable . The first effect of
reduced voltage le that tho SWR reading cannot reach
lnflnlty, but will still
be
accurate at lower readings .
The meter wtll typically read S>~ ' s to
3 • 1
with
B+
as lov as 8 volts , and accurately lndlcate po~er
as low as 7 voles .
In 220 volt countries obtain an
AC
adaptor locally as
we do not carry theta.
If using small batteries you may want to clip one
lead to the LED (does not vold warranty) since the
LEO oonsUJDea about 2/3 of the power.
s :
Rf HOQKUP
Connect the tranemltter to the coax --onnec'tor so
marked . Connect the antenna coax or antenna tuner
to
the~ output
connector. (If these are reversed,the
meter reads reflected, not Corward. POWer and the
SWR reading wil l be off scal e . )
C. OPERATION
Select the lowest ran~e scale Cor power l n use. Select
average or PEP. PEP stands for "peak-envelope-power•
and shows the peak output power , even
i f
this peak
lasts only a 'few milliseconds. PEP
ls
mea su red by
electronic olrouitry which responds much fast er than
the meter. (The m eter takes a fra ction of a second to
swing to t he internal olootronic true PEP power.)
~ote
that SWR ts oomputed
automattcall~
and dis played
directly . Unllke vi rtually all other meter s on the
market, there is no need to do a full scale ad justment
or compute 5WR with a nomograph .
Any
variation of
SWR reading with power l evel is due to a small
voltage drop in the diodes in the Rf haad.(The smal l
box.) This phenom ena occurs with virtually all meters
in t he under $500 claaa . The indicated 5WR will drop
noticeably at 1/10 full scale , and at even higher
scale readings on the 20 watt acale. However,the meter
ls usabl e !or nulling antenna tuners and checking
general antenna condition at powers as low as 1/2
watt or lower . USE THE LOWEST RANGE SCALE THAT DOES
NOT PEG THE POWER METER FOR HOST AOa.JRATE READINGS .
When using "PEP"
you
raay
be
sur prised t o Clnd ttuit
PEP reading on 558 La not much different t han the
PEP or AV reading with "key-down• CW . THIS I S NORMAL.
M odern 5S8 tran811itters with corapression and/or ALC
are peak -POw er H11lted on 558
and
CW , When sending
a strlng or dote
you
will probably notice an increase
in PEP (va . keydown.) This La due to a slightly
smaller droop ln
trane~ltter
pOwer supply voltage ,
yielding increased peak power .