TKR-720 / TKR-820 Interfacing to CAT-300

Up one level (Kenwood)
Up one level (CAT)
Back to Home Interfacing a TKR-720 / TKR-820
to a CAT-300 Controller
Submitted by Mark Tomany N9WYS
Turned into an article by Robert W. Meister WA1MIK

Kenwood TKR-720 / TKR-820 Accessory Connector:

TKR
Pin
# Sig.
Name Signal Function and Specifications Subject to
TAKEOVER
Switch

1 HK External HOOK terminal. Set this terminal to GROUND level before using external PTT. Unlike MIC HOOK, no monitor function is provided. YES

2 LG LINE GROUND. Used for Pin 5 - LI (LINE INPUT). NO

3 DI DIRECT modulation INPUT terminal. External input for QT and DQT: ±750 Hz at approx. 600Ω input impedance. 0.2V p-p. Degree of modulation to be adjusted externally. NO

4 DE Direct detection output / Direct output of undetected (unfiltered) signal. Output impedance 10kΩ. Output level: -10dBs at ±3kHz Deviation, 1 kHz. NO

5 LI LINE INPUT / input for external modulation. Standard modulation is provided at 600Ω, 0.24dBm. Same as MIC level except for input level. YES

6 SG SPEAKER GROUND / GND for output to external speaker. Used for Pin 12 (SO). NO

7 SB +13.8V external power output / Power supply for external equipment. Up to 1A. NO

8 PT External PTT input / Transmission is started at GND level if Pin 1 (HK) is at GND level. YES

9 SI Internal SPEAKER INPUT / Usually connected to Pin 12 via jumper NO

10 DE LINE OUTPUT / Used for output of received signal, for standard modulation at 600Ω, -10dBm. -6dB/oct, 300 Hz to 3 kHz. Interlocked with Pin 13 (CO). YES

11 GN DC GROUND / Ground for DC power supply. NO

12 SO SPEAKER OUTPUT / Output terminal for external speaker. NO

13 CO Internal preset SQUELCH OUTPUT / provides an output interlocked with internal preset squelch, or a tone squelch output when writing tone. When receiving signal, this output is at low level (open collector) with 10mA sink current. NO

14 NC NO CONNECTION / Unused. NO

15 NC NO CONNECTION / Unused. NO

TKR Pin #	Sig. Name	Signal Function and Specifications	Subject to TAKEOVER Switch
1	HK	External HOOK terminal. Set this terminal to GROUND level before using external PTT. Unlike MIC HOOK, no monitor function is provided.	YES
2	LG	LINE GROUND. Used for Pin 5 - LI (LINE INPUT).	NO
3	DI	DIRECT modulation INPUT terminal. External input for QT and DQT: ±750 Hz at approx. 600Ω input impedance. 0.2V p-p. Degree of modulation to be adjusted externally.	NO
4	DE	Direct detection output / Direct output of undetected (unfiltered) signal. Output impedance 10kΩ. Output level: -10dBs at ±3kHz Deviation, 1 kHz.	NO
5	LI	LINE INPUT / input for external modulation. Standard modulation is provided at 600Ω, 0.24dBm. Same as MIC level except for input level.	YES
6	SG	SPEAKER GROUND / GND for output to external speaker. Used for Pin 12 (SO).	NO
7	SB	+13.8V external power output / Power supply for external equipment. Up to 1A.	NO
8	PT	External PTT input / Transmission is started at GND level if Pin 1 (HK) is at GND level.	YES
9	SI	Internal SPEAKER INPUT / Usually connected to Pin 12 via jumper	NO
10	DE	LINE OUTPUT / Used for output of received signal, for standard modulation at 600Ω, -10dBm. -6dB/oct, 300 Hz to 3 kHz. Interlocked with Pin 13 (CO).	YES
11	GN	DC GROUND / Ground for DC power supply.	NO
12	SO	SPEAKER OUTPUT / Output terminal for external speaker.	NO
13	CO	Internal preset SQUELCH OUTPUT / provides an output interlocked with internal preset squelch, or a tone squelch output when writing tone. When receiving signal, this output is at low level (open collector) with 10mA sink current.	NO
14	NC	NO CONNECTION / Unused.	NO
15	NC	NO CONNECTION / Unused.	NO

CAT-300 Repeater Interface (J3):

CAT
Pin Signal Name
or Function

1 UF Switch In #1

2 UF Switch In #2

3 No Connection

4 CTCSS

5 No Connection

6 COR

7 UF Switch Out #1

8 UF Switch Out #2

9 UF Switch Out #3

10 PTT

11 TX Audio

12 No Connection

13 RX Audio

14-15 Ground

16 +12VDC

17-22 Ground

23 TX Audio

24-25 Ground

CAT Pin	Signal Name or Function
1	UF Switch In #1
2	UF Switch In #2
3	No Connection
4	CTCSS
5	No Connection
6	COR
7	UF Switch Out #1
8	UF Switch Out #2
9	UF Switch Out #3
10	PTT
11	TX Audio
12	No Connection
13	RX Audio
14-15	Ground
16	+12VDC
17-22	Ground
23	TX Audio
24-25	Ground

Interface Cross-Connections:

TKR
Pin Signal Name
or Function CAT
Pin

2 Ground 25

4 RX Audio 13

5 TX Audio 11

8 PTT 10

13 COR 6

TKR Pin	Signal Name or Function	CAT Pin
2	Ground	25
4	RX Audio	13
5	TX Audio	11
8	PTT	10
13	COR	6

Other TKR pins:

Pin 1 Hook - to Pin 2 Ground, to disable internal controller.
Pin 9 Internal Speaker - to Pin 12 Speaker Output, so you can hear activity.

Pin 7 +12 VDC - to CAT-300 coaxial power jack.
Pin 11 -12 VDC - to CAT-300 coaxial power jack.

The above interfacing scheme uses the flat/raw detected RX Audio output on pin 4 of the TKR's Molex connector. You will need to install the appropriate de-emphasis component(s) on the CAT-300 controller to deal with this. An alternative is to use filtered/de-emphasized RX Audio on pin 10 of the TKR's Molex connector, but this doesn't always work.

Remember to remove the internal signaling board and install jumpers, to completely defeat the internal time-out timers when using an external repeater controller. See this write-up.

Acknowledgements and Credits:

Connector pin information came from the Kenwood and CAT manuals.

Contact Information:

The author can be contacted at: n9wys [ at ] ameritech [ dot ] net.

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This page originally posted on 29-Apr-2019.

This web page, this web site, the information presented in and on its pages and in these modifications and conversions is © Copyrighted 1995 and (date of last update) by Kevin Custer W3KKC and multiple originating authors. All Rights Reserved, including that of paper and web publication elsewhere.