Installing TU-4c in TW-4000A

[G8ANT]

Have just obtained a TU-4c CTCSS module for my TW-4000a which currently has the 1750Hz board installed.

I had foolishly assumed it would be a straight swap until I discovered that the TU-4c has a 4 pin connector while the 1750 Hz module has a 5 pin connector. The 1750 Hz module only uses pin 1 (tone), pin 2 (Earth) and Pin 3 (EB). I guess there is only one pin because the same tone is used on both 2m and 70cms.

The TU-4c has pin 1 (tone), pin 2 (earth), pin 3 (EB4)(70cms) and pin 4 (EB1)(2m).  I can overcome the problem of the connector size by hard wiring but how do I make the connections to EB1 and EB4?

Thanks.

Simon

[W9GB]

Earlier eHam.net question (2012)
http://www.eham.net/ehamforum/smf/index.php?topic=82190.0

There is a YouTube video (9 minutes) that demonstrates proper installation of TU-4C.
You can contact Kenwood Europe, IF Europe had a different TW-4000A model.

LOOK CAREFULLY for a FOUR PIN (loose cable connector) in harness on bottom of radio.
DIP Switches accessible from bottom of radio, when properly installed.
http://elektrotanya.com/kenwood_tu4a_tu-4b_tu-4c_sch.pdf/download.html

Kenwood TW-4000A Instruction / Owner's Manual
http://ftp.qrz.ru/pub/hamradio/schemes/kenwood/TW-4000A_Instruction_manual.pdf

Kenwood TW-4000A Schematic Diagram
http://www.radiomanual.info/schemi/TW4000_sch.pdf

FIND a copy of the Kenwood TW-4000A SERVICE MANUAL.
Page 39 covers the TU-4c CTCSS installation.
http://marketplaceadvisor.channeladvisor.com/StoreFrontProfiles/DeluxeSFItemDetail.aspx?sid=1&sfid=86409&c=15468&i=196653886

Settings on TU-4c CTCSS module
http://www.universal-radio.com/catalog/fm_txvrs/tu4c.html
DIP Switches
http://www.qsl.net/w/wb4kdi/Kenwood/TW-4000A/tu-4c_settings.gif

[G8ANT]

Thanks for the extensive reply. I already have most of the documentation you mention with the exception of the Service Manual (although I have the schematics for both the TW-4000A and TU-4c). The problem, as I said, is that the only connector in the bottom of my TW-400A is a 5 pin connector currently plugged into the 1750Hz tone unit (type X52-1250-50).

I guess there are a number of variations of this modle  - all mine says on the case is TW-4000A

[W9GB]

Yes, I saw the 5-pin on the schematic diagram,
with the Tone-Burst (1750 Hz) option using the NE555 IC.
The first 3 pin assignments on the connector match the TU-4c, IF correctly installed.
A DVM or VOM can quickly confirm.

The Kenwood TU-4c, according to schematic, uses the MX315 IC
http://www.datasheetcatalog.org/datasheets2/17/179186_1.pdf

LOOKING at the TU-4c schematic, you see that PIN 14 of the MX315 receives VDC for power.
The power is on 2 pins ... One for VHF, the other for UHF DIP switches.
The 2 other lines are for E (Earth, Ground) from pin 7 and T (CTCSS tone output) from pin 11
http://elektrotanya.com/kenwood_tu4a_tu-4b_tu-4c_sch.pdf/download.html

The YouTube video clearly shows a 4-pin connector ...
so different regional models may exist ... OR production change.

[G8ANT]

Thanks for the additional information.

I have cut off pin 5 of the plug so it fits the TU-4c which means power (pin 3) goes to EB4 and no connection is made to EB1 (pin 4). Strangely, it works on 2m and I can trigger local repeaters but I am not able to trigger repeaters on 70cm using the same CTCSS frequencies.

Oh well, keep persevering!

[W9GB]

I was trying to explain to you that DC power for VHF and UHF are SEPERATE, as shown in the Kenwood TU-4c.  Which means you will have 2 DC sources on the plug, depending if VHF or UHF mode is selected!

BTW, while you cut wire for pin 5 .... did you even bother measure with a VOM?  OR to trace it to source in radio?

[G8ANT]

There is no connection to Pins 4 and 5 in my TW=4000A  - my quote "The 1750 Hz module only uses pin 1 (tone), pin 2 (Earth) and Pin 3 (EB). I guess there is only one pin because the same tone is used on both 2m and 70cms."

The lead to the tone module only has 3 leads - Pin 1 Tone output that feeds to the mic amplifier; pin 2 earth and pin 3 that links to the tone switch on the front panel.

[W9GB]

YouTube video of TU-4c module installation in Kenwood TW-4000a
http://www.youtube.com/watch?v=z06F9IQrceo