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Should I update my K3 with K3s parts?


Upgrading the Elecraft K3 with K3s Components -- Bridging the Gap

This short, 50+ page booklet is targeted to K3 owners who now have “The Elecraft K3 – Design, Configuration, and Operation, 2nd Ed” book and who are wondering about or are planning to upgrade their K3 with K3s components.  It will also be very useful for those thinking about buying a used K3.  It offer’s KE7X’s recommendations and describes the operation of the new KIO3B I/O Interface and the new KXV3B Receive Antenna and Transverter Interface.   Printed copies are available at www.lulu.com (check Lulu discount codes) and pdf copies as below.

Table of Contents

Thoughts from Chapter 1:

1.5       Should I upgrade my K3 with K3S Components?

The new K3S model has a number of components that can be added or retrofitted to your standard K3.  Many of these can be retrofitted on your K3 with the appropriate modules shown in Table 14.   The major K3S components to be considered are the KSYN3A, KIO3B, and KXV3B.

1.5.1             KSYN3A

The K3 frequency synthesizer is integral to the operation of the K3.  The superb Elecraft synthesizer design is largely responsible for the commanding receiver and transmitter performance of the K3. 

A new synthesizer design was conceived for the K3S that improves overall performance yet again.  This new synthesizer can replace the KSYN3 in your K3 and many owners have done just that.  The installation procedure is straight-forward and requires you to remove the top cover and remove the original synthesizer and replace it with the new.

For K3 radios with a Sub receiver, the synthesizer in both the Main and Sub receivers must be replaced.  The synthesizer is available on the Elecraft order page, PN KSYN3AUPG.

Recommendation:  Many K3 owners have upgraded their rigs with the new synthesizer and have been happy with the performance improvement.  You will definitely be a better neighbor to nearby stations due to a reduction of receive and transmit phase noise.  If, though, you are not a serious contester or DXer you may want to just keep the current synthesizer.  The especially applies if you have a Sub receiver because then both the Main and Sub receiver synthesizers need to be replaced, doubling the cost of the upgrade.

1.5.2             The KIO3B

The K3 includes an I/O interface, the KIO3A, that allows you to control the radio through a computer USB port with no need to build or buy equipment to convert RS232 signal levels, to receive and send audio for digital modes such as AFSK, RTTY and PSK, or to use external devices such as band decoders for controlling antennas, rotators, and other station equipment. 

When the K3S was introduced, a re-designed KIO3A, designated the KIO3B, was included.  The major differences between the KIO3A and KIO3B are that the latter has a USB interface with sound card serial communications capabilities that can be used instead of an RS232 port for computer-to-radio communications.  This new USB connection replaces the often-messy USB-to-Serial converter used with the KIO3A.  The USB port provides remote control and PTT and CW Keying (equivalent to RTS and DTR signals). It allows the utility and logging programs to work just as if they had a native RS232 port or a USB-to-Serial converter.  The USB connection also provides an audio interface based on a UAC-1 compliant Audio Codec, which gives the K3 its own sound card for digitized line level audio in and out. 

In addition, an RS232/P3 port using a non-standard RJ45 connector can be used for computer communications using a computer’s native RS232 Com port or USB-to-Serial Adapter.  The KIO3B RS232/P3 port connects to a P3 panadapter using a supplied RJ45-to-DE9S or CBLP3Y adapter cable.

For more KIO3B information, see Chapter 10.3, page 164. 

Recommendation:  The main advantage offered by the KIO3B upgrade is the USB audio codec “sound card”.  This reduces the cabling required to use the K3’s FSK, AFSK A, and DATA A modes.  It also eliminates the need for an external USB-to-Serial converter which most stations need for communication with the K3 RS232 serial port.

1.5.3             The KXV3B

The KXV3B is a drop-in replacement for the K3 KXV3A receive antenna and transverter interface.  The KXV3B includes a 20 dB preamplifier for 12-, 10- and 6-meters, which eliminates the need for the PR6-10 preamplifier used with the KXV3A interface.  See Chapter 8.9, page 137.

Recommendation:  Many owners are choosing this upgrade, especially those who use six meters.  Eliminating the external PR6-10 10 dB preamplifier in favor of the internal 20 dB 12-, 10, and 6-meter is a good plan.  You will need either the KXV3A or KXV3B if you are planning to add the P3 panadapter.

Table 14. Available retrofit kits.

K3S Component

Features

Retrofit Kits Available?

KIO3B I/O Interface

Replaces the KIO3A; adds a direct USB interface for computer connections; provides an RS232 connection; provides a sound card interface for digital modes.  See Chapter 10.3, page 164.

Recommendation:  The main advantage offered by the KIO3B upgrade is the USB audio codec “sound card”.  This reduces the cabling required to use the K3’s FSK, AFSK A, and DATA A modes.  It also eliminates the need for an external USB-to-Serial converter which most stations need for communication with the K3 RS232 serial port.

No ETA at this time.

KXV3B Receive Antenna and Transverter Interface

Replaces the KXV3A; includes a 20 dB preamplifier for 12-, 10- and six-meters; PR6 and PR6-10 no longer needed.  See page 95.

Recommendation:  Many owners are choosing to upgrade to a KXV3B.  Eliminating the external PR6-10 10 dB preamplifier in favor of the internal 20 dB 12-, 10, and 6-meter is a good plan.  You will need either the KXV3A or KXV3B if you are planning to add the P3 panadapter.

Available; order KXV3B.

KAT3A 100-W Antenna Tuner

Replaces the KAT3; includes low loss, single relay bypass to reduce losses for well-matched antennas.  See page 158.

Recommendation:  If your K3 does not have a KAT3, you can add the KAT3A.  If you do have the KAT3, the only real advantage of the KAT3A is that a single relay can completely bypass the tuner resulting in lower loss.

Available; order KAT3A.

Main DSP

Replaces the DSP board; Improved receive audio signal.

Recommendation:  There is not enough information available at this time to judge if this is a worthwhile upgrade.

May be available; no ETA at this time.

Front Panel

Real-time clock accuracy adjustment behind the main VFO knob.

Recommendation:  There is not enough information available at this time to judge if this is a worthwhile upgrade.

May be available; no ETA at this time.

KLP3A (10 W Power Amplifier)

Replaces the LPA; redesigned with active distortion canceller for slightly cleaner transmit signal.

Recommendation:  There is not enough information available at this time to judge if this is a worthwhile upgrade.

May be available; no ETA at this time.

KSYN3A Synthesizer

Replaces the KSYN3; produces cleaner synthesized signals leading to better transmitter and receiver performance; has faster switch time to improve TX/RX switching for high speed CW.

In a K3 with a Sub receiver, both the Main and Sub receiver synthesizers must be upgraded.  You cannot upgrade just one.

Recommendation:  Many K3 owners have upgraded their rigs with the new synthesizer and have been happy with the performance improvement.  If, though, you are not a serious contester or DXer you may want to just keep the current synthesizer.  The especially applies if you have a Sub receiver because then both the Main and Sub receiver synthesizers need to be replaced, doubling the cost of the upgrade.

Available now; order KSYN3AUPG.

KPA3A (100 W Power Amplifier)

Replaces the KPA3; redesigned with lower supply voltage drop for slightly cleaner transmit signal.  See Chapter 9.4, page 155. 

Recommendation:  To upgrade a K3/10 to a K3/100, order and install the KPA3A amplifier module.  You may have to do some modifications to the RF board during installation.  If the final transistors in a KPA3 fail, you may have to replace it with the KPA3A.

Available; order KPA3A. RF board modifications required.

RF Board

Multiple performance improvements.

Recommendation:  Don’t even think about upgrading this board.

Not K3 field upgradeable; cost would be prohibitive.

VFO A Knob and Bezel

Softer feel for VFO A knob and upgraded bezel around the display.

Recommendation:  The software knob is nice but these are just cosmetic changes.

Available in the future; no ETA at this time.

KBPF3A General Coverage Receiver Filter

The KBPF3A is an upgrade from the KBPF3. The lowest-frequency filter in the KBPF3A has a cutoff at 100 kHz rather than 500 kHz. This improves typical sensitivity at 137 kHz (2200 meters) to about -120 dBm, and at 472 kHz (600 meters), about -130 dBm.

Recommendation:  If you wish to improve the VLF performance of your K3 you should add the KBPF3A.  For a K3 with a KBPF3 filter, a kit of parts is available to upgrade it to the KBPF3A.

Available now; order KBPF3B; KBPF3 upgrade kit available.

 


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