RADIOHAUS RH-DX640 Installation guide

ASSEMBLING &
INSTRUCTIONS MANUAL
Antena RH-DX640
Cobweb Antenna for portable or
base station operation in
6, 10, 12, 15, 17, 20, 30 and 40 meters

19
Radiohaus Radiocomunicação
Rua Candelária, 672 | Centro | 13330-180 Indaiatuba, SP Brazil
Fone: [phone]
www.radiohaus.com.br
www.radiohausamerica.com
Designed and produced in Brazil by:
Table 1
Example of how to fix the ends of the cables and adjust the frequencies in each band
29500 29180 28840 28500 28150 27790
26280 25970 25700 25410 25080 24776
22240 22075 21784 21600 21390 21190 20985
19046 18880 18710 18540 18370 18175 17990
14530 14410 14315 14210 14110 14010 13905
10390 10335 10290 10280 10230 10175 10115
7250 7215 7190 7160 7125 7100 7070
10m band (28000 ~ 29700 kHz)
12m band (24890 ~ 24990 kHz)
15m band (21000 ~ 21450 kHz)
17m band (18068 ~ 18168 kHz)
20m band (14000 ~ 14350 kHz)
30m band (10110 ~ 10150 kHz)
40m band (7000 ~ 7300 kHz)
(Braid the cable through the central plastic insulator as above. Do the same on both sides)
2) Return the remainder of the wire so that it is adjusted according to the frequency of
each band (above).
wire hanging (dropped).
NOTE: The frequencies above were measured in the prototype and may suffer
1) Pass the cable through hole 3 to the yellow mark and braid through the other holes
changes due to various factors. The frequencies indicated above are just a reference.
as shown in the first figure above.
3) For the 40 meter band, if you need to reach a lower frequency, leave the end of the
Yellow mark

Thank you for choosing the Cobweb Antenna model RH-DX640, a
lightweight and versatile antenna to be used in 8 amateur radio bands (6, 10,
12, 15, 17, 20, 30 and 40 meters).
Ideal for portable operation in field days, expeditions, camping,
portable operations as well as fixed stations. One of the main advantages is the
possibility of operating in the main amateur radio bands, and not taking too
much space.
This is an omnidirectional antenna and does not require a rotator. It has
an excellent SWR on all 8 bands. It can be mounted on a mast or tower and
works very well a few feet obove the ground (3 meters - 10 ft. or higher).
Do not hesitate to contact us in case of any suggestion or questions.
Have good Dxs with your new Cobweb Antenna RH-DX640.
318
(11 m band can be adjusted).....................................
Max. Power.................400W PEP
Gain.............................4.7dBi, 6m (20 feet) off the ground @ 14.2MHz
Minimum SWR ..........1:1
Impedance ..................50 Ohm
Conector .....................PL-259 with coaxial cable 50 Ohm
Weight .........................5.5 kg (12.1 lbs)
Dimension ...................540 x 540 cm (212 x 212 inches)
TECHNICAL SPECIFICATIONS
Type.............................Omnidirectional "Cobweb»
Reception* ..................500kHz to 50,000kHz (50MHz)
Transmission ..............6, 10, 12, 15, 17, 20, 30 and 40 m
Wind resistance ..........Moderate to strong winds
Mast diameter ............38 to 64mm (1-1/2" to 2-1/2")
*MW and SW reception reception with goog efficiency
Main material.............Fiberglass, stainless steel, aluminum
The antenna was tested on air for 60 days, suffering the effects of the
weather such as sun, rain and wind. It proved to be quite stable and throughout
this period, with an Icom IC-7300 and Elecraft KX-3 radios, hundreds of
contacts were made in all bands.
It was noticed that when subjected to rain, the resonant frequency
changes, from 50 to 100kHz above the adjusted one. As soon as it dried, the
frequency returned to that previously set.
COMMENTS
The RH-DX640 antenna prototype was mounted on a roof, on a 3
meter (10 feet high mast).

Always remember that safety comes first! That´s why you need to find
a clear and open space away from power lines. As part of the antenna is made
of fiberglass, wear gloves to handle the tubes to avoid skin irritation. Its also
important to be aware of loose and sharp pieces, as they may hurt your eyes. .
Children may be able to help you with the assembly, but pets will
certainly get in the way. You have no idea how much cats love playing with the
wires and parts of this antenna! Keep the kitties away!
Follow all these steps and safety instructions to properly set up your
Cobweb and go on air!
If you intend to mount this antenna in a vacant lot or in a yard covered
with grass or dirt, we suggest extending a tarpaulin that will help a lot not to
lose any parts that might fall off.
BEFORE STARTING!
This antenna is very light and can be easily assembled by one one
person. The estimated time of assembly is 60 to 90 minutes and to
disassemble, 40 minutes. If you have a tripod with a mast or a pipe
approximately 1.7m long (5.5 feet), it could be a good idea to use it as a
provisory structure to easily assemble and set the initial adjustments.
417
( ) The largest antenna is the 40 meter band and has a 300kHz band-
ends of the wire suspended (dropped) to reach the frequency of the
beginning of the band.
( ) In 17 m band, we have the same situation as the 12 m. A bandwidth
and laborious. That's because it's a very small bandwidth (on-
to adjust this band.
( ) 15 meter band has a bandwidth of 450kHz. Choose a sub-band of
the ressonant frequency many kHz. You will need a lot of patience
preference. Remember that a few inches can move the ressonant
frequency many kHz.
your preference and try to adjust it in that segment.
of just 100kHz (28,068 to 28,168 kHz). Adjust in the center of the
band.
( ) In 20 meter (14,000 to 14,350kHz) adjust in the segment of your
( ) The 3 0 meter band is the shortest of all. With only 50kHz (10,100
ly 100 kHz) from 24,890 to 24,990 kHz. A few inches can move
( ) In case of the 12 meter antenna, the adjustment can be very critical
to 10,150kHz) be very patient to adjust right in the center.
width. You will notice that the adjustment is not so sensitive. Ad-
just to the segment of your choice. If needed, you can leave the
Be careful not to overstretch each wire of the 10 to 40 meter
bands when attaching the ends to the spacers so as not to stress
the fiber structure. It is normal for each antenna element to have
a certain sag. This will not affect the operation.
Use the table on the last page
of this manual to adjust the
center frequencies of each band.
This table was based from our
prototype and may change in
a function of various factors such as
antenna height and closer objects.
Example of how to adjust the wires
over the plastic spacer
ŸDo not handle or install your antenna near power lines
ŸWear gloves when handling fiberglass tubes to avoid possible
irritations or allergies that may be provoked by fiberglass particles
ŸDo not touch the antenna when the radio is trasmitting
ŸAlways use proctetive equipment when installing this product in
high places
TOOLS AND ACCESSORIES NEEDES
(not supplied)
ŸSmall plier
ŸWrench or 8 and 10mm nut driver
ŸMast, tower or tripod and mounting hardware
ŸSilicone sealant
ŸCoaxial cable with male connector (PL-259)

BAND Min.SWR BW. 2:1 BW. 3:1
6 meters
10 meters
12 meters
15 meters
17 meters
20 meters
30 meters
40 meters
1.0:1 180kHz 350kHz
1.2:1 130kHz 268kHz
1.0:1 1240kHz 2.240kHz
1.0:1 170kHz 255kHz
1.2:1 186kHz 340kHz
122kHz 250kHz
77kHz 145kHz
1.2:1
1.2:1 77kHz 145kHz 1.2:1
1.2:11.2:1 83kHz
145kHz145kHz
178kHz
( ) 7 Plastic band spacers (10 to 40m)
( ) 2 "U-64" Clamps
( ) 2 M6 Split washers
( ) 2 Sets of antenna elements (6, 10 and 12 meter)
( ) 2 Sets of antenna elements (15, 17, 20, 30 and 40 meter)
( ) 1 Tube clamp, 21mm (27/32 inch - small)
( ) 18 M6 x 40mm Hex Bolt (large)
( ) 3 M6 x 25mm Hex Bolt (small)
( ) 21 M6 Flat washers
( ) 21 M6 nuts6
( ) 4 telescopic fiberglass tubes (element arms)
IDENTIFICATION OF THE PARTS INSIDE THE BOX
( ) 1 Central support set in stainless steel and aluminum
( ) 1 Matching box with feed arm
( ) 1 Central mast with support ropes and tighteners
( ) Miscellaneous parts for assembly:
( ) 33 Hex nut, nylon, M5
( ) 3 Hex bolt, nylon, M5
( ) 5 Cable clamp, nylon
( ) 30 Nylon fastening elements
( ) 3 Releasable Cable Tie, nylon
( ) 8 Tube clamp, 25mm (1 inch - large)
( ) 24 Snap Rivet, nylon
5
16
( ) Start by setting the 6 meter band (50 to 54 Mhz). Start checking
ve the releasable cable tie further towards outside the center of the
you prefer, move the cable tie towards the inner of the center, cau
antenna. If the frequency is above 54MHz or above the frequency
In a first step check the resonant frequency of each band. If it's what
you expected, raise the antenna as high as possible and it's ready to use. If not,
proceed to fine-tuning, band by band.
smaller staying .sing a piece of wire to loose
( ) The 10 meter band has a range of 1,700kHz and it is essential that
you choose the preferred segment.Adjust to increase or decrease
the resonance frequency. If it is below 50 MHz you will need to mo
USE THE TABLE ON THE LAST PAGE FOR ADJUSTMENT
the ends of the wires. Thread the wire through the first hole of the
spacer and collect the leftover weaving through the remaining ho-
quency.
les. A few inches more or less can cause a big shift in the center fre-
The table below shows measurements taken on our prototype. For each
band we have the smallest SWR obtained, and the bandwidth (BW) obtained
with a SWR of 2:1 and 3:1.

15
ADJUSTMENTS
We deliver the antenna with a pre-set mark on each band. Note the
yellow mark on the end of each wire. But this is just a reference based on the
results obtained from the prototypes and so you will need to check it out and
fine tune it to your operating preference. And always remember this basic rule:
to lower the resonant frequency, increase the length of the antenna. To
increase frequency, decrease length.
The development of the first prototypes required a lot of dedication
and time until we could achieve a good efficiency of this antenna. All this work
was rewarded with many QSOs and DX on all bands with the antenna
installed a few meters (feet) from the ground.
Adjusting your Cobweb antenna is a process that requires a lot of
patience and time to get the best performance.
( ) You must have assembled your antenna in a wide place. Make sure
these obstacles that could interfere with performance.
( ) If you have an antenna analyzer, it would be ideal for you to make
trees, walls and fences. Leave at least a 2 meter (6 ft.) distant from
adjustments more easily.If an analyzer is not available, use a trans-
ceiver with power reduced to 5W.
that when raising the antenna it is not too close to obstacles such as
This antenna has limited badwidth with an acceptable SWR. Thus, it is
important that you define which is the preferred segment of operation in each
band and try to leave each band adjusted to your preference. But, you will have
a better result using and antenna tuner.
BASIC RULE TO ADJUST
Higher frequency - Decrease the length
Lower frequency - Increase the length
( ) Take the two L-shapped plates (small) and place them on the under
( ) Pass an M6 x 25mm bolt (small) into the center hole (A). Place an
side of the large plate as shown in figure 1.
( ) Pass two M6 x 40mm hex bolt (large) into each L-shapped plate.
( ) Place the large mouting plate on a table or worktop.
ASSEMBLY
M6 flat washer over the bolt and tighten gently with a nut. Over the
ce the point "B". Tighten the nut in this position and remove the
1. Central support bracket assembly
bolt, thread the support mast with ropes and make the white dot fa-
mast.
A
B
Figure 1
L-shaped plates must be assembled
in these position
Bigger size
Central support
(large plate)
Central bolt
(PointA)
( ) On the four threads of these bolts (figure 2), place two 25 mm
so it doesn't fall out.
(1-inch) plastic tube clamps (large).
( ) Pass flat washers and nuts but do not tighten. Just insert the nut
Tube clamp
(1-inch)
Flat washer
Nut
Figure 2
6
L-shaped plates must be assembled
in these position

tube clamp. Note that this clamp is smaller than the others.
( ) In the remaining holes, insert six 25mm (1") tube clamps (large).
( ) Insert another 14 large hex bolts into the remaining holes. In the
( ) Note that all bolt heads must be on the same side of the plate.
place indicated with the circle (figure 3) insert a 21mm (27/32")
( ) Pass washers and nuts on each screw. Don't tighten at that time.
Just insert the nuts so they don't fall out.
sert a tube into each pair of clamps. Note that the masts must be in-
troduced until they are flush with the innermost clamp (figure 4).
( ) Pick up the 4 telescopic fiberglass masts. Keep them closed and in-
Figure 3
Figure 4
Insert each mast until
they get close with the
limit of the clamps!
7
14
( ) Connect a good quality 50 Ohm coaxial cable with the shortest
possible length between the antenna and the radio. Roll up a ba-
lun on the coaxial cable itself, keeping the coils together with
( ) Secure the coaxial cable to the matching box tube with the last
tape. This balun should have 6 turns in a diameter of approxima
tely 8cm (3") and should be close to the connector (fig. 8).
releasable cable tie.
the coaxial connector with self fusion tape or silicone sealant.
( ) If your goal is to keep the antenna in a fixed installation, protect
Fig. 8 - Coaxial cable balun
White dots up!

four bolts also serve to fix two tube clamps.
( ) Take the aluminum plate (fig. 5) and insert it into the underside
( ) Note that the two L-shaped plates will be at the bottom and its
If necessary, lock the nuts in position using pliers.
of the previously assembled set between the "L" plates.
( ) Using a 10mm (3/8 inch) wrench securely tighten all hex bolts.
( ) Pass two M6 x 25mm hex bolts (small), two flat washers, two
spring washers and two nuts.
( ) Use four of the six remaining holes to secure the set to a 38 to
ly need to use 4 holes to keep the assembly tight and secure.
"U-64" clamps provided. The plate has six holes but you will on
suggest that you keep the central support always mounted to fa-
( ) Tighten firmly so that the set is very stable and fixed.
( ) Keep the antenna as high as you can reach to finish mounting.
64mm (1-1/2" to 2-1/2") telescopic pole, mast or pipe. Use two
( ) If your intention is to use this antenna in portable operations, we
cilitate temporary installation.
Figure 5
Aluminum plate
Side view of the center
support already with clamps
8
( ) Repeat the same operation on both ends of all bands from 10 to
marking represents the approximate center frequency of each
wires about 40 cm (16") over the tube in the inner direction and
spacer must be installed symmetrically.
2 or 3 holes as shown in photo 4.
( )Do not pull excessively to avoid straining the end of the fiber
( ) Place the plastic spacers at the ends of each band wires.
secure (Point B in figure 9) with a releasable cable tie. Allow
( ) Pass the wire through the first hole of the spacer and pull until
( ) Using the plastic tighteners, stretch the five ropes so that the ele-
ments are slightly up.
( ) In the case of the 6 meter antenna (the innermost one), align the
excess of wires to hang downward.
( ) Note that at the end of each wire there is a yellow mark. This
band.
reaching the mark. Pass the wire through the third hole so that
the spacer does not come loose. Braid the rest of the wire every
tubes. It is normal for the wires to have a sag.
40 meters.
( ) For 10, 12, 15, 17, 20, 30 and 40 meters antennas, a plastic band
Photo 4 - How to attach the wires to the spacers
13

faces the top.
be (figure 6).
( ) Firmly tighten this clamp.
( ) Insert this tube into the remaining tube clamp, so that the hole "A"
2. Assembly of the Matching Box and antenna elements
( ) Take the feed arm and screw it firmly onto the matching box tu-
white dots that should line up.
( ) Fully open the four fiber telescopic masts.
( ) With a little patience, make the smaller holes coincide between
( ) Insert a removable snap rivet into each of these 24 holes. If you
intend to use your antenna for portable operations (subject to as-
the outer and inner tube (photo 1). To make it easier, note the
so that they are not damaged.
sembly and disassembly) be careful when removing the rivets
Photo 1 - Detail of the positioning of the small holes, placement and
removal of the nylon snap rivet
A - Fix only one hex nylon bolt and nut
B - Fasten with a releasable cable tie
C -Thread the rope through the nylon clip and fasten
together with the fastening element
D -Thread the rope through a nylon clamp and secure with a
hex nylon bolt and nut
In the remaining 30 points, fix the fastening elements with
the clamps facing the outside of the antenna.
AA
BB
Spacers
Figure 9
912
Matching
Box
Coaxial
connector
Hole A
Thread into
the feed arm
Feed arm
Figure 6
CC CC
CC
D
It is normal for each antenna wire to have a certain sag.
This will not affect the operation.

Matching
Box
Coaxial
connector
Hole A
Male Female
White
dots
40m
30m
20m
17m
15m
12m
10m
6m
Figure 7
( ) Identify the pair of 3-wire antenna elements (6, 10 and 12m).
( ) Connect to the corresponding female connector on the matching
box. Note that one of the connectors has a white dot that must
match the marking on the box connector (figure 7)
and secure with a nylon nut. Do not tighten too much to prevent
( ) In all other large holes, attach an nylon fastening element using
damage to the fiberglass.
of the tubes (photo 2). Do not tighten too much.
( ) Insert a nylon hex bolt in each of the two points "A" (figure 9)
a nylon nut to secure. Place all the cable clamps towards the end
each band. With the weight of the wires, it is natural for the tu-
of the plate. Simply screw the mast firmly.
band fastening element (the larger antenna) using a nylon clamp
( ) Release all five ropes. The shorter rope must be attached to the
( ) Connect both sides, respecting the identification.
( ) Pass all the wires inside each of the nylon clamps, according to
( ) Identify the 5-wire antenna pair (15, 17, 20, 30 and 40m).
that must be attached to the each fastening element (photo 3).
bes to bend.
( ) Connect the male connector that has the white dot to the female
ning connector.
matching box tube (point "D" in figure 9). Use a nylon clamp
( ) Install the central mast with support ropes on the central thread
( ) The other ropes must be attached to each of the four 40 meter
connector that has the white dot and the other one to the remai-
and nylon nut.
10 11
Photo 2 - How to fix the fastening elements to tubes
Photo 3 - Cable clamp assembly detail