An intriguing radio which looks great for unattended HF data use, since it is engineered for 100% duty cycle at 25W.

Has no data port on the back, but an accessory breakout cable can be added. Pinout is on p14 of the service manual, linked below.

Kenwood TK-90 instructions

Kenwood TK-90 ALE feature instructions

Kenwood TK-90 service manual

Requires programming. Both serial and USB-serial mic jack programming cable is available as a Kenwood part (see below) or off brand USB versions are also available. This implies it is just straight serial so a generic USB serial cable with an RJ45 plug crimped on the end may be suitable.

Has a “VFO mode” which implies it might not always have a “VFO mode” available.

Is ALE-capable, presumably with add-on.

Accessories

• KAT-1 - B51-8304-00 - Automatic antenna tuner
• KRK-5/6DH - B51-8445-20 - Remote kit
• KCT-31 - B51-8573-00 - PC interface cable
• VGS-1 - B51-8669-00 - Voice guide & storage unit
• KCT-39 - Accessory breakout cable (stocked by radioswap)
• KPG-102D - Programming Disc (CD)
• KPG-46 / KPG-46A - Serial programming cable
• KPG-46U - USB programming cable
• KCT-18 - Ignition sense cable
• KES-3 - External speaker
• KIF-2 - 2.7kHz SSB filter
• YF-107C - 500Hz CW Filter for TS-480HX/SAT
• KLF-2 - Line noise filter
• KMB-10 - Key lock adapter
• KMB-9 - Mounting bracket
• KMC-30 - Standard hand microphone
• KMC-32 - Hand microphone with keypad
• KMC-35 - Slim-line hand microphone
• KMC-36 - Slim-line hand microphone with keypad
• KPE-2 - ALE unit
• KRK-5 - Panel Separation Kit (Requires KCT-22M, 22M2 or 22M3)
• PG-20 - DC cable (7m)
• VGS-1 - Voice guide/Storage unit

For best results it has been recommended to use a KMC-32 keypad microphone for ease of use with the menus.

Software

Remove the top lid of the radio- 8 screws.

Turn trimmer VR852 fully clockwise, for max sensitivity to TX audio input.

Install KCT-39 - accessory breakout cable.

Boot radio into dealer mode by holding down B while powering up. Scroll down to FUNCTION, and press D. Scroll to menu item 19: DI LEVEL and press D. Turn up to 9, maximum. Press the square button. Press the red button twice to exit and reboot.

Build a cable (the plug parts come with KCT-39):

• RX Audio → pin 14 (sky blue)
• TX Audio → pin 15 (turquoise)
• PTT → pin 6 (yellow)
• Ground → pin 8 (blue)

Some other recommended settings while in DEALER mode:

• M2 MIN VOLUME: 0 - means the radio can boot with the volume turned to zero
• M12 TOT: TX time out timer. Set to, say, 3 minutes
• M13 VFO TX PWR: self explanatory
• M19 DI LEVEL: data input audio level, set as required
• M20 DEO LEVEL: data output audio level, set as required
• M22 DATA S-BAND: which sideband will data be transmitted on - generally set to USB

NB - currently feeding 2.2V P-P is resulting in rather low RF output. Providing more audio than that does result in more RF output, but the levels required seem excessive and I chickened out at about 4V. Cause as yet unknown.

NB - DI LEVEL is “data input audio level”, DEO LEVEL is “data output audio level”

The A-D buttons are programmable, but the functions they have shipped to us with are as follows.

Pressing A in VFO mode gets you a blinking cursor. Move the cursor left/right with <C and D> buttons. Change that digit with CH up and CH down. Exit with the red button.

Pressing B cycles between preamp / attenuator settings.

Pressing C gets you the clarifier settings.

Pressing D cycles between modes (i.e. USB, LSB, DATA, CW, AM, FSK)

Pressing square gets you a basic menu.

Booting the radio with B held gets you a DEALER menu. This is pretty safe. More in here than the basic menu.

Booting the radio with A held gets you an ADJUSTMENT menu. Warning: this is a service menu, for radio alignment, and you can break things very easily in here, requiring realignment which requires lab tools and knowledge.

There is supposed to be a TEST mode when booting the radio with D held, but this does not appear to be enabled.

All of the above is in the service manual.

1. DM
2. MIC
3. PTT - common with a point labelled PTT/TXD
4. SB
5. HK - connected to a pin labelled RXD0 and to +5V via a 4.7k resistor
6. ME
7. GND
8. BLC