Elecraft K3EXREF User Manual
ELECRAFT
HIGH-PERFORMANCE 160 – 6 METER
TRANSCEIVER
K3EXREF
FREQUENCY LOCK OPTION
INSTALLATION AND OPERATION
Revision A2, October 31, 2012
Copyright © 2012, Elecraft, Inc.
K3
All Rights Reserved
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Contents
Introduction............................................................................................................................................. 3
Customer Service and Support ............................................................................................................................ 3
Using the K3EXREF............................................................................................................................... 4
Installing the K3EXREF ........................................................................................................................ 4
Anti Static Protection Required .......................................................................................................................... 4
Preparing for Installation ..................................................................................................................................... 5
Tools Required ................................................................................................................................................ 5
Firmware Required .......................................................................................................................................... 5
Parts Included .................................................................................................................................................. 5
Installation Procedure .......................................................................................................................................... 6
Removing the K3Top Cover and Chassis Stiffener ........................................................................................ 6
Installing the TMP Cable ................................................................................................................................ 6
Installing the K3EXREF Board....................................................................................................................... 9
Reassembly ................................................................................................................................................... 10
Elecraft manuals with color images may be downloaded from
www.elecraft.com.
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Introduction
Elecraft's 1-Year Limited Warranty
This warranty is effective as of the date of first consumer purchase (or if shipped from factory, date product is shipped to 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 to Elecraft at time of order to insure warranty coverage.
What is covered: During the first year after date of purchase, Elecraft will replace defective or missing parts free of charge (postpaid). We will also correct any malfunction to kits or assembled units caused by defective parts and materials. Purchaser pays
inbound shipping to Elecraft for warranty repair, Elecraft will pay shipping to return the repaired equipment to you by UPS ground
service or equivalent to the continental USA and Canada. Alaska, Hawaii and outside U.S. and Canada actual return shipping cost
paid by 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 responsibility of 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.
The K3EXREF option locks the K3's reference oscillator frequency to an external 10 MHz source by
automatically controlling the REF CAL function. While locked to the external source, the K3’s reference
oscillator frequency is maintained within 2 Hz. Since the K3EXREF does not phase lock the K3’s reference
oscillator, the external 10 MHz source has no impact on the K3’s phase noise performance. For best
performance we recommend your K3 be equipped with the KTCXO3-1 high stability (0.5 ppm typ.) reference
oscillator.
The option consists of one small pc board that mounts on the existing KREF3 board and a cable assembly that
brings in the external 10 MHz signal to the board from the K3’s rear panel. No soldering is required to install the
K3EXREF option.
Customer Service and Support
Technical Assistance
You can send e-mail to k3support@elecraft.com and we will respond quickly - typically the same day Monday
through Friday. 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 (We want to make sure everyone succeeds!)
If necessary, you may return your Elecraft product to us for repair or alignment. (Note: We offer unlimited email
and phone support to get your kit running, 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 in Aptos. We will give you the address to ship your kit to at the time of
repair authorization. Packages shipped to Aptos without authorization will incur an additional shipping charge
for reshipment from Aptos to our repair depot.
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Using the K3EXREF
If you are installing the K3EXREF yourself, go directly to Installing the K3EXREF below.
The operation of the K3EXREF is automatic, once a suitable signal is applied to the K3’s rear-panel REF.
connector. To confirm the external reference controls the K3 reference oscillator:
Turn the K3 on. Confirm that TECH mode is on (CONFIG:TECH MD On).
Monitor the K3’s reference oscillator frequency (CONFIG:REF CAL)
Connect the external 10 MHz signal source to the K3 rear panel REF. connector. The 10 MHz source
should have a signal level between +4 dBm and +16 dBm, nominal. For square wave sources, 2VDC to
3.3VDC peak is optimum. If the source is a 5V logic level, use a 50-ohm resistor in series with the
input. Caution: To avoid damage to the K3EXREF, do not exceed these levels.
An asterisk symbol will appear (REF CAL) will appear after several seconds indicating the K3’s
reference oscillator is now controlled by the external 10 MHz source. The will blink on and off as
long as a 10 MHz signal is being received.
Manual control of REF CAL is now disabled. LOCKED will appear if you try to adjust the VFO A knob.
It will remain locked to avoid sudden jumps in frequency if the 10 MHz source is accidentally lost. If
the 10 MHz source is removed, the will stop blinking and the K3 will maintain the last reference
oscillator frequency. To regain local control, remove the external source and cycle the K3’s power off,
then on again.
NOTE: If you want to maintain the calibration provided by the external 10 MHz source even when the
10 MHz source is not used, note the REF CAL frequency and then, after disconnecting the external
source and regaining local control by cycling the K3’s power, manually set REF CAL to that frequency.
Installing the K3EXREF
Anti Static Protection Required
We strongly recommend you take the following anti-static precautions (listed in order of importance) to avoid
ESD (Electro Static Discharge) damage:
Leave ESD-sensitive parts in their anti-static packaging until you install them. The packaging may be a
special plastic bag or the component’s leads may be inserted in conductive foam. Parts which are
especially ESD-sensitive are identified in the parts list and in the assembly procedures.
Wear a conductive wrist strap with a series 1-megohm resistor. If you do not have a wrist strap, touch a
bare metal ground briefly before touching any sensitive parts to discharge your body. Do this frequently
while you are working. You can collect a destructive static charge on your body just sitting at the work
bench.
WARNING
DO NOT attach a ground directly to yourself without a current-limiting
resistor as this poses a serious shock hazard. A wrist strap must include a 1megohm resistor to limit the current flow. If you choose to touch an
unpainted, metal ground to discharge yourself, do it only when you are not
touching any live circuits with your other hand or any part of your body.
Use a grounded anti-static mat on your work bench.
No soldering is required but if you choose to use a soldering iron for any reason, be sure your iron has
an ESD-safe grounded tip tied to the same common ground used by your mat or wrist strap.
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