Building an X-band
transceiver with a little
determination and a
radio budget
Brian Thorson, AF6NA
Vice-President
San Bernardino
Microwave Society (SBMS)
SBMS, founded in 1955,
is a non-profit technical organization
dedicated to
the advancement of communications
above 1.0 GHz.
http://www.ham-radio.com/sbms
Meetings every 1st Thursday of the month
7:00 PM
The American Legion Hall
1024 Main Street
Corona, CA
SBMS is an ARRL-Affiliated Radio Club.
Several SBMS Members have set
10 GHz distance records
Many SBMS members have been
ARRL 10 GHz and Up Contest Winners
SBMS still holds the record for
the highest contest score.
10 GHz means ten billion cycles per
second. A billion is hard enough to
comprehend in dollars or other quantities.
But at “X” and other microwave bands,
the physics of electromagnetics is a bit
different. Hollow tubes are the best
transmission lines, and antennas take on
unusual shapes.
Making a QSO is a very special event.

How many people here have operated radios other
than FM and repeaters?

How many people have operated a contest?

How many people installed their own equipment?

How many people consider themselves technical?

How many people have gone camping?

How many people know how to use a soldering
iron?

How many people have an all-mode VHF/UHF rig?

How may in this room have “worked all bands?
What’s
This?
33 cm
23 cm
13 cm
9 cm
6 cm
3 cm
S-Band:
C-Band:
C-Band:
X-Band:
K-Band:
V-Band:
W-Band:
902.0-928.0 MHz:
1240-1300 MHz
2300-2310 MHz; 2390-2450 MHz
3300-3500 MHz
5650-5925 MHz
10.0-10.5 GHz <<<
24.0-24.25 GHz
47.0-47.2 GHz
76.0-81.9 GHz*
119.98-120.02 GHz
142-149 GHz
241-250 GHz
Above 300 GHz
*76-77 GHz has been suspended temporarily
This could be the next challenge for some
of you Hams with some experience but
who are looking for a new avenue or thrill
in Amateur Radio!

Goleta to San Diego on 280 mW at 10368.100 MHz: 300
km (186 mi.)
http://no.nonsense.ee/qthmap/
SBMS, founded in 1955,
is a non-profit technical organization
dedicated to
the advancement of communications
above 1.0 GHz.
http://www.ham-radio.com/sbms/
Meetings every 1st Thursday of the month
7:00 PM
The American Legion Hall
1024 Main Street
Corona, CA.
Hey, isn’t microwave just
“line-of-sight” communications?
NO !!!!
How did I work Mt. Potosi in Las Vegas last
month from Los Banos, CA, (529 km)
shooting over Mt. Whitney,
the tallest peak
in the contiguous 48 states ???
Los Banos to Mt. Potosi – 529 km
The 900mi shots to AD6FP,
N6CA and KH6WZ required
large antenna gains and high
power to extend signals
beyond the duct and inland
another 100+ miles and over
6000' mountains and up the
California Central Valley.
Coastal ducting is
caused by an abrupt
change in the
moisture and
temperature of the
atmosphere at the
boundary between
the relatively cool
wet layer of air
hugging the ocean
and the dry warm air
above it. This
boundary zone acts
like a lens for radio
and optical signals
which then follow
the curvature of the
earth for great
distances.
During the first half of the 2007 10GHz and Up
contest, the North American distance record for
terrestrial X-Band contacts was broken and rebroken 5 times.
This milestone for ham radio X-Band operations
was made possible by a one-man DXpedition by
Frank Kelly, WB6CWN/4C2WH in DL34wt.
The average contact distance was 1,178km
(732mi) and the accumulated score on just two of
Frank’s log pages was over 65k points!
Baja California,
Mexico
XE
DL34wt
Operation in Mexico
is advantageous
because there is a
long over water path
between Southern
California and
numerous points
along the western
shores of the Baja
Peninsula. This path
is host to weather
that produces coastal
ducting, a principal
propagation mode.
Frank made 53 10GHz contacts from DL34wt on the first weekend.
The NA 10GHz DX record was broken five times, first by W6QIW
in DM04am at 1315km (817 mi). Steve’s record lasted approx. 7
minutes
Then N6CA and KH6WZ worked Frank from CM94xm
(1320km/820 mi), then CM95qi (1426km/886 mi) and again from
DM05ax (1448km/899 mi)
Finally, on 8/19/2007 at 0845, AD6FP completed a contact with
Frank at CM96wa, a record-breaking distance of 1460km
(907.2mi)
The 10GHz Frazier beacon was copied in DL34wt at 1286km - a
new DX record for 10GHz beacon DX
This is the DB6NT-based rig before exchanging the 24-inch M/ACOM dish with the new 30-inch offset-feed dish.
The revised
KH6WZ rig,
with transverter
system on the
ground and IF
radio placed on
the antenna
deck. The 30-in.
dish is
supported with
an N6CA
folding support
structure made
with aluminum
tubing.
SBMS, founded in 1955,
is a non-profit technical organization
dedicated to
the advancement of communications
above 1.0 GHz.
Meetings every 1st Thursday of the month
7:00 PM
The American Legion Hall
1024 Main Street
Corona, CA.
http://www.ham-radio.com/sbms/
 The
X-Band rigs used can be duplicated;
typical performance can be built with ham
techniques and resources
• RX performance: 1dB NF, 25dB gain
 For terrestrial work, there is little improvement below a
2dB system NF due to ground noise (about 150K). No need
to spend $300 on an EME preamp!
• TX performance: 6W to 10W range
• Antenna: 30-in. plus dish
 Bigger antennas are better – But are they practical and
transportable?
 Offset feed dishes have higher efficiency, and are
becoming more popular. Other dishes (prime-focus) are a
low side-lobe design and not designed for efficiency
• Attend SBMS meetings and get acquainted
• GOTA – Get On The Air with a 10 GHz Rig
• Make it ‘rugged” enough to withstand a ride
in your car / truck, etc.
• Partner with another experienced and
successful operator for the contest
• Try it before you say it can’t be done
• The next point “down range” near the tip
of Baja is over 1000 miles
• XE2HWB and XE2HWH in La Paz, Baja,
Mexico now have their own 2W 10GHz
radios built by WB6CWN
The record can definitely be extended on the Northern side
 Building
a radio from available parts is one
of the greatest of Ham radio traditions.
 Microwave
amateur radios are not available
off the shelf from any manufacturers.
 This
is really one of the most rewarding
parts of becoming a microwave ham.
 No
two radios are exactly alike, they all have
their own design, shape factor, performance
specs, strengths and weaknesses.
 Most
amateurs have a “QRP” radio, that is,
a low-power radio. The Yaesu FT-817 is a
great unit and many experienced
microwavers prefer it as an “IF” radio
 Many
people have an old satellite dish
they no longer use, such as a Dish
Network or DirecTV dish attached to the
side of the house
SBMS, founded in 1955,
is a non-profit technical organization
dedicated to
the advancement of communications
above 1.0 GHz.
Meetings every 1st Thursday of the month
7:00 PM
The American Legion Hall
1024 Main Street
Corona, CA.
http://www.ham-radio.com/sbms/
 If
you don’t have one, eBay is a good
source of used radios. ($300 to $700)
Try to find one with the
feed assembly in
place.
That way, you don’t
have to do so much
math to find the focal
point.
$ FREE !!
A
transverter is the heart of the system.
 DB6NT from Kuhne Electronics GMBH


280mW / 1.2 dB NF …About $650 US plus shipping from Germany
http://www.kuhne-electronic.de/en/products.html
 Down East Microwave (DEMI)
 3W/1.5 dB NF ………….. $775
 http://www.downeastmicrowave.com/
A
simple 280 mW radio will make many
QSOs (DB6NT based system shown)
A high stability
“master oscillator”
will be necessary
to tune in SSB
signals at X-band.
A Rubidium or
“Rubi” and an
OCO are shown
$ 99.00 on eBay
 Getting
the transverter, the T/R switch, the
cooling fans, (power amp), and everything
to switch on when you press the “PTT”
button may take a little creativity and
electronic design.
I
used relays from
Radio Shack
 Solid
State
Sequencers are
available
SBMS, founded in 1955,
is a non-profit technical organization
dedicated to
the advancement of communications
above 1.0 GHz.
Meetings every 1st Thursday of the month
7:00 PM
The American Legion Hall
1024 Main Street
Corona, CA.
http://www.ham-radio.com/sbms/
 Waveguide
is the best transmission line
for the microwave bands. WR-90 is the
best for 10.368 GHz. (3/4” copper pipe)
 ‘Semi-rigid’ coax, such
as UT-141T, is
rated for microwave frequencies, but is
more lossy than waveguide.
 Waveguide-to-Coax
used near the
Antenna feed
point to convert
from coax to the
waveguide so the
microwave power
can be applied to
the reflector.
transitions are




Feed Horn Assembly
T-R Switching
Antenna focal point
D.C. Supplies




Microwaves are a very “elusive” quantity - losing a
dB here and a dB there in a microwave system is
very easy to do.
Use the best semi-rigid coax and the shortest
lengths possible.
Avoid getting “kinks” in the semi-rigid, and dents
in the waveguides.
Losses on the receive side can seriously affect your
minimum discernable signal (MDS).
 To
minimize power losses, microwave
frequency components should be located as
close to the reflector feed as possible.
 K6JEY has a great example of this.
Doug Millar, PhD., K6JEY



Your best time investment will be spent getting
high efficiency out of the reflector antenna and
feed system.
The lowest cost and lowest noise gain you have in
your microwave system is your antenna. If you take
care to put the feedhorn at the right spot and point
the feedhorn correctly, your antenna gain will be
maximized and noise minimized.
If you just “rough it in” the antenna will perform
poorly. The receive system will be noisy, making it
hard to receive weaker signals and expensive
microwave Watts will be wasted.
 Getting
the focus and feed angles correct
will take a bit of geometry and algebra.
 Paul Wade, W1GHZ, has
done extensive
research work into microwave reflector
antennas and has published excellent
tutorial material on his website:
http://www.w1ghz.org/antbook/contents.htm
 Additional
information on offsets and
feeds is also helpful.
 W1GHZ
developed a
very useful method of
finding the focal
point with a string.
 The
string is marked
with the calculated
values of focal length
and illumination
angle
 When
making
measurements on
your dish, measure
to the edges of the
reflective surface,
rather than the
outside lip of the
sheet metal. This
will yield better
agreement with
calculated values.
 Bisect
the
offset
reflector
vertical
illumination
angle and
that’s the spot
to point at,
not the
center of the
reflector.
SBMS, founded in 1955,
is a non-profit technical organization
dedicated to
the advancement of communications
above 1.0 GHz.
Meetings every 1st Thursday of the month
7:00 PM
The American Legion Hall
1024 Main Street
Corona, CA.
http://www.ham-radio.com/sbms/
 Assembling
and de-bugging a
microwave radio is a very timeconsuming and gratifying activity….
 …. So
much so, that some Hams have
turned it into a multiple-year project, and
some haven’t finished yet!
 The
Goal:
GOTA!
A
well-built microwave radio is one that
works well not only in the lab, but has
been ruggedized to take a car ride all
weekend and not fall apart en-route.
 Should
be able to arrive at a roving
location and be on the air in less than 10
minutes.
 Steve, W6QIW: Close
to the Dish
 John, KJ6HZ
Has all parts on one plate
 Every
year on
the last
weekend of July
(30 JUL 2011)
 Fairview
Park,
Costa Mesa, CA
 EIRP
and MDS
measurements
SBMS, founded in 1955,
is a non-profit technical organization
dedicated to
the advancement of communications
above 1.0 GHz.
Meetings every 1st Thursday of the month
7:00 PM
The American Legion Hall
1024 Main Street
Corona, CA.
http://www.ham-radio.com/sbms/