Elecraft K4

The Elecraft K4 is a high-performance, direct-sampling, SDR transceiver. It covers the 160...6m bands, with continuous receive from 100 kHz to 54 MHz. 10W and 100W models are available. It can be used with internal or external transverters to cover bands above 6 meters. Among the K4's notable features: Large color touch screen as well as support for an external high-resolution monitor, extensive easy to use controls, rich analog and digital connectivity, dual receive (all models), built-in data modes, wide-range automatic antenna tuner. The K4's compact size and weight, combined with 11-15 VDC operation and low current drain, make it suitable for field-day, travel, or home station use. This Elecraft transceiver come with high resolution mini-panadapter for each receiver. An advanced fine-tuning aid with its bandwidth as narrow as ±1 KHz. The user can turn it on by tapping either receiver's Signal-meter or by tapping on a signal of interest. Band-stacking switches and per-receiver controls are both intuitive and versatile, adapting to operating context. Built in PSK, RTTY, and CW text decode/display. S-meter with nominal S9=50uV for all preamplifier and attenuator settings.

Elecraft K4 Dual-Panadapter Mode

The K4's user interface provides a symmetrical display of settings for VFO A (main RX) and VFO B (sub-RX). There's a full set of icons for each, as well as dual S-meters. Each also has its own high-resolution fine-tuning aid, the mini-pan, which can be displayed by touching a signal of interest or by tapping the associated S-meter. This symmetry extends to the main and sub panadapters as well. The screen capture shows dual-panadapter mode, with side-by-side displays that maximize waterfall height.

There are three models:

Elecraft K4

The basic transceiver, with one set of receive filters and one analog-to-digital converter (ADC) allowing the main and sub receivers to be set for the same or different bands.

Elecraft K4D

Includes all of the features of K4. Add an additional direct sampling ADC module and a second set of band-pass filters. This allows the two receivers to use different antennas, for diversity receive. With two sets of BP filters also optimizes signal handling when the receivers are on different bands and/or different antennas.

Elecraft K4HD

Includes all of the features of K4D. Add a dual superheterodine 8 MHz IF module, for competitive field day and contesting receiver. Each superhet section includes two XTAL filters, for SSB and CW.

Kit version

A no-soldering kit version of the Elecraft K4 is planned. Ham builders will learn about advanced radio technology as they proceed. All modules are factory aligned and tested.

All K4 models provide simultaneous dual receive on the same or different bands/modes, though the additional receiver module in the K4D and K4HD improves signal handling during dual-receive operation on different bands. The second receiver also permits diversity reception: the use of different antennas for the two receivers to counteract fading. K4 transceiver are also upgradeable by the user at any time: a basic K4 can be upgraded to a K4D by installing the KRX4 option. Similarly, a K4D can be upgraded to a K4HD by installing a KHDR4 module. Other internal options and external accessories work with all models, including a wide-range ATU (KAT4), MH4 microphone, SP4 external speaker.

Elecraft K4 built-in operating manual :

Easy! Tap the [?] button on the K4 front panel, identified by a yellow arrow - see below, to bring up the built-in operating manual. To see information on the controls most recently used, tap the [LAST CTRL] button one or more times. Use the VFO A knob to scroll through text, navigate using underlined links and the forward/back arrow buttons. Tap the table of contents or magnifying glass buttons to search by topic.

Elecraft K4 built-in operating manual

A button is provided to select either the small manual format, shown here, or a larger format using the entire screen to reduce the need for scrolling.

Elecraft K4 multifunction controls :

There are three multifunction knobs located to the left of the LCD. Each of these knobs controls a related group of functions, see arrows.

XMTR

Power output, VOX delay, and two per-mode parameters (WPM and PITCH, or MIC and CMP). Press and hold the knob to set MONitor level.

FILTER

Receive filter passband width (BW) and shift (SHFT), or high-cut (HI) and low-cut (LO). Press and hold the knob to NORMalize the passband.

RF/SQL

Main receiver RF gain (M.RF) or squelch (M.SQL), and sub receiver RF gain (S.RF) or squelch (S.SQL). Press and hold the knob to adjust BALance.

Elecraft K4 multifunction controls

Tap a knob to alternate between the associated two buttons on the LCD. Tapping the button itself alternates between one of its two functions.

Elecraft K4 mini-panadapter tuning aid :

The mini-pan, see yellow arrow, is a tuning aid that shows signals near the VFO frequency. Mini-pan spectrum is resampled at a narrow bandwidth, not just magnified. This ensures excellent resolution even when the main panadapter is configured for a wide span. A pointer at the top of the mini-pan is shown during AUTO-SPOT or SPOT to identify the nearest relevant signal.

Elecraft K4 mini-panadapter tuning aid

There are two ways to bring up the mini-pan: Tap the S-meter on the applicable receiver, which keeps the mini-pan displayed until this area is tapped again, or HOLD your finger or mouse on a signal of interest - then slide it left or right to fine-tune using the mini-pan.

Elecraft K4 text decode/encode :

Text decode/encode is supported in CW, PSK, and FSK modes. An example window in CW mode is shown below. This feature is turned on by tapping [MAIN RX] or [SUB RX], followed by [TEXT DEC]. The upper portion of the text window shows 1 or 3 lines of received text. The lower portion shows one line of transmitted text, which can be entered with either a keyboard or keyer paddle.

Elecraft K4 text decode/encode

The operator can send/receive text in the same or different modes on both VFOs also, with both dual panadapters and dual text decode selected.

The receive graphic equalizer is displayed by tapping [MAIN RX] or [SUB RX], followed by [RX EQ]. EQ values can be adjusted by tapping +/-, at the ends of the sliders, by moving the sliders or by rotating the VFO A knob. The target pitch for VFO A knob adjustment can be selected by tapping one of the Hz buttons, or by adjusting a slider. If [FLAT] is tapped, all sliders are centered and all EQ values become 0 dB.

Elecraft K4 receive equalizer

TX EQ is similar, accessed by tapping the [TX] primary function button, followed by [TX EQ].

Elecraft K4 rear panel and connections :

Elecraft K4 rear panel and connections

Elecraft K4 microphone pinouts and configuration :

An Elecraft MH4 or other K4/K3S/K3-compatible Mic can be used with the front panel jack, see pinout below. To select the front-panel or rear-panel mic, turn bias or preamp on / off, or enable / disable mic buttons, tap [TX] on the LCD, then use [MIC SEL] and [MIC CFG]. Bias must be turned On for electret microphones (e.g. MH4, MH2, MD2, Proset). It must be Off for dynamic mics (e.g. Heil mics using HC4 or HC5 elements).

Elecraft K4 front panel microphone pinouts

The Elecraft K4 has both front and rear microphone inputs. Voice-mode audio can also be obtained from the LINE IN jack or via the soundcard interface (USB-B). To select which microphone input to use, tap [TX], then [MIC INP]. Select FRONT, REAR, LINE IN, FRONT+LINE, or REAR+LINE. If the front or rear mic has been selected, it can be configured by tapping TX > MIC CFG.

Elecraft K4 microphone configuration

Elecraft K4 accessory pinouts :

The ACC interface provides signals that are most often used to control an Elecraft KPA-series linear amplifier and/or KAT500 ATU via a 15-wire control cable. It can also be used with band decoders, switchers, transverters, or other devices.

Elecraft K4 accessory (ACC) pinouts

The ACC pins BAND0-BAND1-BAND2-BAND3 are open-drain with internal pull-up resistors to 5V. Band data is based on the frequency of the transmit VFO (VFO A in non-split, VFO B in split) as follow:

Elecraft K4 price

We have collected for your convenience the Elecraft K4 sale price (UK Pounds) and its trend over time. Useful to guarantee a cheaper purchase of this radio and to put it for sale in the second-hand market. Of course offers, accessories, warranty terms and conditions can lead to different figures.

Price	Date	Condition
GBP 3735.00 (4499USD)	2023-mar	Brand-new 10 Watt model
GBP 2990.00 (4099USD)	2021-feb	Brand-new K4 model
GBP 3646.00 (4999USD)	2021-feb	Brand-new K4D model