Funk Amateur FA-VA5 User instructions

A embly and Operating Manual
Kit for an ea y to u e
vector antenna analyzer
for u e in the frequency range
10 kHz to 600 MHz.
Vector
Antenna Analyzer
FA-VA5
Ver E 1.0
25.6.2018

BX-245 • 1© Box 73 Amateurfunkservice GmbH 2018
Radio amateu s who build thei own antennas app eciate the value of avecto antenna analyze . This device is
cha acte ized by high accu acy, small dimensions and easy ope ation. It allows one-po t measu ements in the f e-
quency ange f om 10 kHz to 600 MHz and has a USB po t fo connection to compute s.
Vector Antenna Analyzer FA-VA5
SUPPORT DEPARTMENT OF GERMAN HAM RADIO MAGAZINE “FUNKAMATEUR”
Experiments with antennas make up a sub-
stantial part of the hobby for many radio
amateurs.
The measurement of standing wave ratio
(SWR) and the determination of the
impedance values are inseparable.
The SWR can be estimated when transmit-
ting using aSWR meter, but more exten-
sive and accurate data is obtained using an
antenna analyzer.
However, such instruments are often ex-
pensive whilst cheaper devices often lack
accuracy. The FA-VA5 closes this gap. It
is the successor to the successful FA-VA4
which was also developed by Michael
Knitter, G5MK [1].
The VA5 is afull-featured, vector-measur-
ing device with afrequency range of 10
kHz to 600 MHz, (Table 1) offering com-
pact dimensions and a USB port for con-
nection to acomputer.
Vectorial measurement means that, unlike
ascalar instrument, not only the SWR is
measured and displayed, but also the value
of the impedance, including the signed
imaginary part. The so-called SOL (Short,
pen and Load) compensation, originates
from professional instruments, and is used
for the calibration of the device and pro-
vides precise measurements in different
configurations.
The FA-VA5's graphic display shows the
complex impedance, standing wave ratio,
complex reflection coefficient, capaci-
tance and inductance.
An audible SWR indication using the
built-in piezo buzzer is also available. The
analyser kit consists of an SM -pre-as-
sembled printed circuit board, agraphic
display including backlight, and a USB
module in a specially designed enclosure.
The microcontroller on the board is al-
ready programmed. The USB connection
allows not only the interaction of the FA-
VA5 with Vector Network Analyzer soft-
ware installed on the computer (VNWA
Application – see the corresponding chap-
ter in this manual) but also permits
firmware updates by the VA5 user. The
VA5 Menu structure is easily understood
by newcomers provided you spend alittle
time reading relevant instructions in this
manual. The VA5 kit includes SOL cali-
bration elements, which are usable up to
about 100 MHz. A high-quality calibration
kit, covering afrequency range up to 600
MHz, can be purchased at [1].

2 • BX-245 © Box 73 Amateurfunkservice GmbH 2018
Technical data
Table 1: Technical data
Frequency range 0.01 MHz … 600 MHz, (resolution: 1 Hz)
Measuring range limits SWR ≤ 100, Z≤ 1000 Ω*
Measurement result full impedance value (resistance and reactance), including sign
Accuracy ≤ 2 % (0.01MHz ≤ f≤ 200 MHz, Z< 1000 Ω)
ynamic range Mode Precise: 80 dB to 200 MHz, 50 dB 200 MHz … 600 MHz
of Return Loss Mode Standard: 75 dB to 200 MHz, 45 dB 200 MHz … 500 MHz
Fast mode: 70 dB to 200 MHz, 40 dB 200 MHz … 500 MHz
Frequency stability 0.5 ppm (–30 °C … +85 °C)
Signal processing 24-bit A C, 16-bit SP, 32-bit calculation
Power supply 2 ¥1.5V AA battery
Measuring input 50 Ω, BNC
Output signal Squarewave
f= 1 MHz, RL= 50 Ω:
P1= 5.6 dBm (1st harmonic, fundamental)
P3= –4.0 dBm (3rd harmonic)
P5= –8.3 dBm (5th harmonic)
f= 200 MHz, RL= 50 Ω:
P1= 4.5 dBm (1st harmonic, fundamental)
P3= –7.2 dBm (3rd harmonic)
P5= –15.3 dBm (5th harmonic)
Current consumption 38 mA** (65 mA) at 1 MHz, 47 mA** (85 mA) at 200 MHz,
Load resistance 50 Ω, lighting switched off, single frequency measurement Z
Current real time clock 0.9 μA
imensions 127 mm ¥86 mm ¥23 mm (L ¥W ¥H)
Mass 280 g incl. AA batteries
*Measurements beyond that, but possible with less accuracy
** Mean, peak in parentheses
Important
This construction manual was created
with great care. All hints and advice
contained therein are important for
asuccessful construction! The same
applies to the order of the assembly
steps.
Any revision of the FA-VA5 Assembly
and User manual will be published as apdf
file on www. ox73.de. Please check this
website regularly.
You'll also find videos on assembling and
operating the VA5 Antenna Analyzer once
these are published.

BX-245 • 3© Box 73 Amateurfunkservice GmbH 2018
The following tools are required for as-
sembly:
– temperature-controlled soldering iron
60 … 80 Wwith pencil soldering tip,
– solder 0.5 ..1.0 mm with flux core
– 100 Wsoldering iron with chisel-shaped
soldering tip,
– PCB side cutter pliers
– flat-nose pliers,
– 3mm slot screwdriver,
– Phillips screwdriver,
– two 1.5V AA batteries (Mignon) for
power supply.
Before fitting the board, the contents of
the kit should be checked off against the
parts list in the appendix.
nAssembly of the board
Afew remaining components are to be fit-
ted on the top side of the main board,
i.e. where the six-pin header of the pro-
gramming interface is already located.
The position of the individual parts can be
identified on the assembly plan (Fig. 2).
Switch and USB Interface board
First, the slide switch S1 is soldered to the
topside of the board. It should rest flush
on the board with no space underneath, its
actuating knob must be horizontal with re-
spect to the board surface (Fig. 3). The
easiest way to achieve this is if only one
of the solder pins of the switch is soldered
first. After that, the switch can still be eas-
ily aligned while heating the solder joint.
When the correct mounting position is
found, all pins and the two housing tags
are soldered.
The USB Interface Board is to be soldered
directly to the top side of the main board
with the supplied mica washer inserted for
isolation purposes. The washer must lie
flat and be placed exactly between the cor-
responding soldering surfaces (Fig. 4).
The front edge of the USB socket then
projects slightly beyond the main board to
terminate flush with the housing shell. Tin
Fig. 1: View of assembled FA-VA5 – ower
switched off
Building instructions

4 • BX-245 © Box 73 Amateurfunkservice GmbH 2018
one of the relevant solder pads of the main
board first, then positioned the USB board
including mica washer and fix the USB as-
sembly with some solder. To see if every-
thing fits properly, screw the motherboard
with four M3 screws in the housing lower
shell and then fit on the upper shell. The
USB socket must now sit exactly behind
the rectangular cut-out on the left side of
the housing. If necessary, the accuracy of
fit can now be corrected relatively easily.
If everything is correct then continue and
solder all 16 solder pads of the USB
Board to the main board.
Fig. 3: Slide switch soldered in the correct
position
Fig. 4: USB interface board correctly posi-
tioned
Fig. 2: Assembly plan of the FA-VA5 with components to be fitted
USB module
SG1
battery
battery

BX-245 • 5© Box 73 Amateurfunkservice GmbH 2018
Display
A graphic LC display with integral LE
backlight is used to display the measured
data.
Both components are already delivered as-
sembled as aunit and are only to be sol-
dered in certain places. Caution: Make
sure the display is flush with the LE
backlight so that there is no gap, then pro-
ceed to solder all six connections of the
two three-pin display contacts on the back
of the backlight (Figure 5a). Also solder
the two outer connections of the 20-pin
contact strip (Figure 5b).
It is recommended to use asuitable base
under the display during soldering in order
to fix it flush on the lighting unit.
Caution: The protective film on the glass
surface of the display must first be re-
moved before assembling the housing.
If you forget this, you will see ablack
line on the display that suggests the
glass is damaged.
Fig. 5a: Display with backlight; all six connections must be soldered on top of the backlight
CB
Fig. 5b: View of the 20-pin contact strip of the display after assembly. Only the two outer pins
are soldered on top of the backlight CB. Remove the protective film from the display by
pulling the red tab.

6 • BX-245 © Box 73 Amateurfunkservice GmbH 2018
Socket strips
The three socket strips for contacting the
LC display are fitted next. The pre-assem-
bled display can be used conveniently as a
gauge for their orientation.
Caution: The lower edge of the plastic
body of the socket must have a uniform
distance of exactly 7 mm to the board, to
ensure that the display eventually sits at
the correct height above the main board.
To achieve this, cut the cardboard strip
(supplied in the kit) into four parts and
place it during soldering as shown in Fig-
ure 6a. Before soldering the female con-
nectors, put these strips on the pins of the
display. To do this, place it upside down
on the work surface and carefully slide the
three socket strips onto the display pins.
Make sure the socket strips are flush with
the display board as the 20-pin strip is
prone to bend slightly.
Place the display together with the socket
strips on the board. Next the four card-
board strips are inserted (Figure 6b) then
turn over whole assembly so you can sol-
der the female connectors on the underside
of the board.
The female connectors must be exactly
vertical after soldering.
Push-button switch, piezo buzzer,
battery holders and BNC socket
The three push-buttons, the piezo buzzer
and the battery holders are fitted and sol-
dered next.
Fig. 6a: Four cardboard strips are used for
setting the distance between female con-
nectors and the CB.
Fig. 6b: Main CB view before soldering the female connectors of the LC display; The card-
board strips must be pulled out after soldering, also the display is removed (unplugged)
again before fitting the remaining components.

BX-245 • 7© Box 73 Amateurfunkservice GmbH 2018
Caution: All these components must be
mounted so they sit tight on the main
board. Remove the protective foil of the
piezo buzzer and locate the positive termi-
nal. Fit this component so the positive pin
points in the direction of the battery holder.
Next fit the battery holders, observing cor-
rect polarity (Figure 2). Caution: the
spring contact is the negative pole. The
solder terminals of the battery holders are
made of spring steel. Use suitably robust
side-cutter-pliers to trim the excess length
of the switches, battery holder and buzzer
terminals, making sure that these termi-
nals do not touch the housing later.
Finally, fit the BNC socket and solder on
the board. Again, this part must sit flush and
be aligned horizontally and at right angles
to the edge of the board. The two ground
pins are to be soldered on the underside of
the board with a 100 Wsoldering iron to
ensure the solder flows well in order to
avoid cold solder joints. At the same time,
the soldering time should be kept relatively
short so that the insulation inside the socket
is not damaged (Figure 8). The thin termi-
nals should also be cut after soldering in or-
der to avoid short circuits with the housing.
Functional test and final Assembly
Before installing the board into the hous-
ing, ashort functional test is required. First
fit the three plastic caps on the push-but-
tons and fit the previously assembled dis-
play in the corresponding sockets. Ensure
the slide switch is set to the off position
(Figure 8), then insert two 1.5 Vbatteries
with the correct polarity and switch on the
device with the slide switch.
The start-up welcome message should
now appear briefly on the display, the FA-
VA5 then switches to measuring mode.
If the display remains blank, then all sol-
der joints made in the previous steps must
be carefully checked and reworked if nec-
essary. Once the functional test is complet-
ed, move the slide switch back to the off
position and remove the batteries from
battery holders. The fully assembled board
is shown in Figure 7.
Installation in the enclosure
First, the four rubber feet are inserted into
the lower shell of the en closure. It is helpful
Fig. 7: FA-VA5 Main rinted Circuit Board: fully assembled
Fig. 8: Slide switch in position Off

8 • BX-245 © Box 73 Amateurfunkservice GmbH 2018
to pull with the flat-nose pliers on the thin
rubber nipple on the inside and at the same
time to turn the rubber foot slightly. Then
cut the protruding rubber nipples to 2 mm
with the side cutter (Figure 9) so that they
do not touch the board later. The board is
now inserted by sliding the BNC jack into
the housing lower shell and the four M3
screws are screwed in at the corners of the
board and gently tightened. The BNC
socket must then be screwed together with
the toothed washer and nut and gently
tightened.
To avoid mechanical stresses on the main
board, the four fixing screws of the board
should be loosened and tightened again,
then do the same with the nut of the BNC
socket.
Now insert the batteries observing correct
polarity. Next the housing cover is fitted
and fastened with four M3 countersunk
screws.
Finally, attach the Instrument type label to
the bottom of the housing! The FA-VA5 is
now ready for operation and can already
be used in uncalibrated mode.
General notes on operation
The FA-VA5 antenna analyzer can be used
as ameasuring device immediately after
assembly. It then operates in uncalibrated
mode and the displayed results are subject
to ahigher error than is the case after a
correct calibration. The uncalibrated mode
can always be selected later via the Setup
Menu if, for example, there are doubts
about the validity of the stored calibration
data.
nCautions
Please note the FA-VA5 is a sensitive mea-
suring device. No RF energy should
reach the test socket to avoid destroying
the components at the input! This could
happen when transmitting with the anten-
na connected in close proximity of the
VA5. Likewise, static charges must be
kept away from the test socket. Isolated
antenna structures must therefore be dis-
charged by grounding them first.
Rechargeable batteries should not be
used in the FA-VA5 because there is no
electronic protection against over-dis-
charge and there is no battery charging fa-
cility in the instrument. eep discharge
makes rechargeable batteries useless and
can even destroy them. Leaking batteries
can also cause damage.
The FA-VA5 is designed to make opti-
mum use of 1.5V alkaline cells. In order
to achieve the longest possible battery
life, it is advisable to use the display back-
light only if it is otherwise impossible to
read the display. In daylight or outdoors
the backlight is usually not needed. A
dimmed brightness setting will also help
to save power.
The number of measurements or display
cycles should be selected to produce are-
peat rate that is sufficient for the measure-
ment in question. These parameters can
be changed in the Setup menu and have a
significant influence on the power con-
sumption and thus on the life of the bat-
teries.
It is advisable that BNC plugs should be
turned slightly back and forth after the
bayonet catch engages to improve contact
engagement. Otherwise, under certain cir-
cumstances, “inexplicable” measuring er-
rors may occur.
Fig. 9: Cut rubber feet after insertion into the
housing