ELECRAFT AXB1 User manual

1
ELECRAFT AX2OWNER’S MANUAL
AX2
MINI-20 METER
WHIP ANTENNA
Page 2
MODIFYING THE AX2
FOR 17 - 6 METERS
Page 6
AXE1
40 METER
EXTENDER
AXB1
WHIP BIPOD
Page 5
AXT1
TRIPOD ADAPTER
E740361 Rev. A 5 , October 9, 2021 Copyright 2021, Elecraft, Inc. All rights reserved

2
Introduction
The Elecraft AX2 is a miniature 20 meter telescoping whip that
disassembles into a 6” (15 cm) whip and 2.5” (6 cm) base unit. It
is intended to be used with an ATU (antenna tuner).
While the AX2 is supplied configured for 20 m, it can be modified
to cover any single band from 17 through 6 m by removing turns
from the inductor and optionally shortening the counterpoise wire
(see pg. 6). The AXE1 40 m extender can also be used with the
AX2. Refer to the AXE1 instruction sheet for details.
The AX2 is ideal for pedestrian mobile, “stealth” operation, or
whenever dipoles, verticals, long wires, and other full-size
antennas cannot be erected. It can be used in three ways:
• HT-style (shown here with an Elecraft KX2 transceiver)
• On a table-top with a right-angle BNC adapter and an AXB1
whip bipod (see page 5)
• Mounted on a tripod or other support using an AXT1 tripod
adapter (refer to AXT1 instruction sheet).
FOR BEST RESULTS, USE THE AX2 WITH AN ATU
(automatic antenna tuner). As with all short whips,
resonance will be in or near the target band, but can vary
with terrain, radial height, body capacitance, etc. High SWR
without an ATU may result reduced power output and/or RFI.
All Elecraft transceivers have optional wide-range internal
ATUs that are fully compatible with the AX2. An external
ATU such an Elecraft T1 may also be used.
Caution
• DO NOT TOUCH THE WHIP WHILE TRANSMITTING.
You may receive an RF burn even at a few watts.
• Do not overtighten the whip on the base unit, as hardware
may become loose when the whip is removed.
• The AX2 is not intended for vehicle-mounted use or for
permanent outdoor installations.
• Keep the whip collapsed when not in use.
• Always use at least one radial (included). This improves
transmit signal strength by ~20 dB and reduces RF burn risk.
NOTE: The AX2 has a new design that reduces BNC connector
wobble. However, the whip may still tilt slightly.

3
AX2 Setup
• If you’re using the AXE1 40 meter extender, follow the setup
instructions in the AXE1 instruction sheet.
• Thread the whip into the base and extend it. Do not
overtighten the whip, as this may cause base unit
hardware to come loose.
• Plug the AX2 into your transceiver’s BNC jack for HT-style
operation. For right-angle use with an AXB1, see page 5. For
use with a tripod and an AXT1, see the AXT1 instruction sheet.
• ATTACH AT LEAST ONE COUNTERPOISE WIRE (or radial)
to your transceiver’s ground screw. Otherwise, your transmit
signal will be as much as 20 dB weaker (4 to 5 S-units). An
insulated counterpoise wire with a spade lug at one end is
supplied with the AX2. When using a KX2 or KX3, secure the
spade lug to the rig at the thumb screw closest to the antenna
jack. (An option for the KX2 is to use a mini-banana plug, e.g.
Elecraft KX2GNDPLUG, with the quick-release ground jack on
the left side panel.)
• Match the antenna to the transceiver using an ATU or with
manual length adjustments as described below.
Using an ATU
The resonant frequency of any short whip can be affected by
many factors, radial length, changes in terrain, and in the location
of the radio relative to the operator. An ATU can compensate,
eliminating tedious whip or radial length adjustments. (An ATU is
also required when using the AXE1 extender.)
To match using an ATU: Tap the ATU tuning switch on the radio
or tuner. If you’re using a K4 / K3S / K3 / KX3 / KX2, tapping the
TUNE switch a second time may result in a better match.
Manual
Adjustment
Manual adjustment of resonance to a target frequency may be
possible.
To adjust antenna resonance manually: Check the SWR at
both the low and high end of the desired band. If SWR is higher at
the low end of the band, lengthen the radial. If SWR is higher at
the high end of the band, shorten the radial or reduce the length of
the telescoping whip.
NOTE: In cases where it is difficult to achieve a low SWR (< 3:1),
transmitting may still be possible at reduced power. Elecraft
transceivers can be safely used at high SWR.

4
Operating
Tips
• At QRP power levels, CW and certain data modes (including
FT8) will have an advantage over SSB.
• If you need to improve your transmit signal, elevate the AX2
above ground by standing or using a tripod. When operating
outdoors, seek high ground, or an area with a downslope in a
preferred direction. Such a slope may act as a reflector.
Indoors, extend the telescoping whip outside a window if at all
possible, and allow the counterpoise wire to hang outside the
window as well. Use a balcony if available.
• When operating pedestrian mobile (/PM), let the counterpoise
wire trail out behind you. As terrain changes, SWR may
fluctuate during transmit. An ATU, if available, can
compensate; tap the ATU tune button if SWR is high.
• Try operating during contests when there’s lots of activity (most
weekends). Contest stations often have high-gain antennas,
benefitting both ends of a QSO.
• Rather than call CQ, try answering strong stations who are
calling CQ or just completing a contact. A strong signal is often
an indication that propagation is excellent in that direction.
• Tune slowly, especially when listening for weak signals. As an
example, SOTA (Summits On The Air) CW stations can often
be found between 14058 and 14063 kHz, and SSB on 14340
kHz, but they may be very weak.
QRP operation with a short whip can be both rewarding
and challenging.
For times when conditions are poor, we recommend also
carrying a lightweight wire antenna. A simple random-length
antenna can be made from two 25’ (7.5 m) lengths of #26
“Silky” (thewireman.com). Counterpoise wires supplied with
the AX2 and AXE1 can also be used. Throw one wire into a
tree and lay the other on the ground, or into a second tree.
Attach the wires to the transceiver via a BNC-to-binding post
adapter, such as our model BNC-BP. Elecraft ATUs will
usually match this efficient antenna on 40 through 10 m.

5
AXB1
Whip Bipod
NOTE: The legs of
the AXB1 may not be
in electrical contact
with the whip’s BNC
connector, so they
should not be used
as a radial wire
attachment point.
A whip antenna used with a right-angle BNC may tip over due to
wind load. To stabilize a whip in light to moderate winds, an
AXB1 bipod can be used as described below.
To use the AXB1:
• Attach a right-angle BNC adapter (Elecraft
BNC-RA or equivalent) to the antenna.
• Snap the AXB1’s plastic clip firmly onto the
knurled part of the AX2’s BNC connector as
shown by the upper arrow at left.
Caution: To detach the plastic clip from the
antenna, do not snap it back off, as this can stress
the connector. Instead, slide the connector back
through the clip by pushing firmly on the BNC
adapter where indicated by the lower arrow.
• Adjust AXB1 leg angle and height as needed.
• In strong winds, orient the radio so the antenna
is facing into the wind, or strap the AXB1 to the
surface. Holes are provided in the legs.
• Firmly tighten the AXB1’s thumb screw.
• For storage or transport, fold the legs of the
AXB1 together. An AX2, AXB1 and KX2 will all
easily fit in an Elecraft CS40 or ES40 bag.

6
Modifying the
AX2 for
Other Bands
The AX2 as supplied is resonant in or near the 20 meter band.
By removing turns from the toroidal inductor, it can be re-
resonated for any single band from 17 through 6 meters.
Note to antenna experimenters: While resonance of the AX2
and its counterpoise can be adjusted using a vector network
analyzer (VNA), the frequency will shift during field use due to
changes in terrain, etc. This is not a concern if an ATU is used.
Substituting other core types: Max core size is 0.5” (12.7 mm)
in diameter. Use a high-Q iron-powder, phenolic, or air core, not
ferrite. Micrometals/Amidon -6 or -7 is recommended. -2 is also
suitable for low bands and -10 or -17 for the highest bands.
Wire requirements: The supplied core uses enamel wire having
a very high temperature rating. If standard wire is used, inspect
the insulation for discoloration or other artifacts at max power.
Follow these steps to modify the AX2:
• Gently pry off the cover at one edge (see arrow at left).
• Unsolder the toroid leads from the solder lug and BNC jack.
• The standard winding has 22 turns (about 8 µH, resonant near
14 MHz). Remove turns on the toroid as described below, re-
strip the lead, then re-solder both leads. (Do not use sharp
tools when removing turns, as you may nick the enamel wire.)
These turns counts are starting points. It is possible to
further fine-tune the turns count or squeeze/spread the
turns. If an ATU is used, this should not be necessary; it
will typically provide coverage of one to three bands.
18 MHz: 17 T (remove 5) 21 MHz: 15 T (remove 7)
25 MHz: 12 T (remove 10) 28 MHz: 11 T (remove 11)
50 MHz: 8 T (remove 14)
• OPTIONAL: Adjust the length of the counterpoise wire (per
page 7) to match the target band. Start on the long side and
trim if desired. This step is optional because an ATU
compensates for non-ideal counterpoise length. But note
that if the counterpoise is long relative to the base/whip
resonant frequency, the antenna may exhibit two resonant
frequencies when swept with a VNA.
• BAND IDENTIFICATION: Clip off the nub(s) on the cover
corresponding to the band(s) covered by the modified whip.

7
Counterpoise
Wires
The counterpoise (or radial) wire supplied with the AX2 is cut for
20 m. The inductor in the base unit has also been adjusted to
provide resonance close to the 20 m band with this radial length.
The AXE1’s longer counterpoise wire is usable on 40 m. Adding
more radials may yield improved results on one or more bands.
During pedestrian-mobile operation, a single “dragged
counterpoise” wire is typically used to minimize the risk of
snagging or other hazards. Optimal length for a dragged
counterpoise varies with many factors, but the length most often
used is: L (ft) = 185 / F, or L (m) = 56 / F (F in MHz).
A good starting point for elevated radials (e.g., using the AX2 with
a tall tripod or mast) is a full quarter wavelength: L (ft) = 234 / F,
or L (m) = 71.3 / F. This length also works best on 40 m (AXE1).
Radial length adjustments to achieve resonance can be tedious.
An antenna analyzer is recommended. NOTE: A VNA can also
yield inaccurate results, varying between workbench and field.
AX2
Specifications
Resonant
Frequencies
(approx.)
Supplied
Radial Wire
Max. Power
Construction
Dimensions
(approx.)
Weight
AX2: ~14 MHz (20 m)
AXE1: ~7.2 MHz (40 m)
Resonant frequencies may vary +/- 400 kHz
or more due to variations in terrain, antenna
height, body capacitance, and length of
radial(s).
AX2: 13 ft. (4 m). AXE1: 33 ft. (10 m).
Includes spade lug.
15 Watts. If RFI symptoms are observed,
reduce power or move antenna farther from
the transceiver.
Corrosion-resistant whip and hardware;
Lexan outer tube; high-Q inductors using
#20 AWG high-temp enamel wire.
Whip: 6” (15 cm) collapsed, 45” (115 cm)
extended. Base unit: 2.5” (6 cm). AXE1
extender: 6” (15 cm).
AX2: 3.2 oz. (90 g). AXE1: 2.0 oz. (55 g).

8
Customer Service and Support
Technical Assistance
You can send e-mail to [e-mail] and we will respond quickly – typically the same day
Monday through Friday. If you need replacement parts, send an e-mail to [e-mail].
Telephone assistance is available from 9 A.M. to 5 P.M. Pacific time (weekdays only) at 831-763-4211.
Please use e-mail rather than calling when possible since this gives us a written record of the details of
your problem and allows us to handle a larger number of requests each day.
Repair / Alignment Service
If necessary, you may return your Elecraft product to us for repair or alignment. (Note: We offer email
and phone support, so please try that route first as we can usually help you find the problem quickly.)
IMPORTANT: You must contact Elecraft before mailing your product to obtain authorization for the
return, what address to ship it to and current information on repair fees and turnaround times.
(Frequently we can determine the cause of your problem and save you the trouble of shipping it back to
us.) Our repair location is different from our factory location. We will give you the address to ship your
kit to at the time of repair authorization. Packages shipped without authorization will incur an additional
shipping charge for reshipment to our repair depot.
Elecraft 1-Year Limited Warranty
This warranty is effective as of the date of first consumer purchase (or if shipped from the factory,
the date the product is shipped to the customer). It covers both our kits and fully assembled
products. For kits, before requesting warranty service, you should fully complete the assembly,
carefully following all instructions in the manual.
Who is covered: This warranty covers the original owner of the Elecraft product as disclosed to
Elecraft at the time of order. Elecraft products transferred by the purchaser to a third party, either by
sale, gift, or other method, who is not disclosed to Elecraft at the time of original order, are not
covered by this warranty. If the Elecraft product is being bought indirectly for a third party, the third
party’s name and address must be provided at time of order to ensure warranty coverage.
What is covered: During the first year after date of purchase, Elecraft will replace defective or
missing parts free of charge (post-paid). We will also correct any malfunction to kits or assembled
units caused by defective parts and materials. Purchaser pays inbound shipping to us for warranty
repair; we pay shipping to return the repaired equipment to you by UPS ground service or equivalent
to the continental USA and Canada. For Alaska, Hawaii, and other destinations outside the U.S.
and Canada, actual return shipping cost is paid by the owner.
What is not covered: This warranty does not cover correction of kit assembly errors. It also does
not cover misalignment; repair of damage caused by misuse, negligence, or builder modifications;
or any performance malfunctions involving non-Elecraft accessory equipment. The use of acid-core
solder, water-soluble flux solder, or any corrosive or conductive flux or solvent will void this warranty
in its entirety. Also not covered is reimbursement for loss of use, inconvenience, customer assembly
or alignment time, or cost of unauthorized service.
Limitation of incidental or consequential damages: This warranty does not extend to non-
Elecraft equipment or components used in conjunction with our products. Any such repair or
replacement is the customer. Elecraft will not be liable for any special indirect, incidental or
consequential damages, including but not limited to any loss of business or profits.