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Author Topic: Kenwood TR-7400A Power Cord  (Read 7424 times)
FLORIDAMARINE
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Posts: 4




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« on: March 20, 2013, 05:07:36 PM »

Hi, first post...

I am a rank amateur to the Ham/Amateur radio thing, but not new to comms/radios. 

I am an active duty LtCol of Marines, communications officer - but admittedly more IT then radio - BUT I still know enough to know what I am doing around a radio and have been using CB's since I was my sons age...so 19 years  Roll Eyes.  Well, maybe a bit longer then that.

My son (10) and I are studying to take the Tech Exam, and I recently acquired a Kenwood TR-7400A...missing a power cord.

I have exhausted google and bing looking for one, or how to make one.

Can anyone steer me in the right direction?

Sean
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K2LGO
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Posts: 117




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« Reply #1 on: March 20, 2013, 05:54:43 PM »

Hi Sean...
   I had a 7400A a long time ago, and as I recall the power cord was a two connector configuration, with a locking steel collar that screwed into the back of the radio...if its the one I am describing, that could be a tough one...you might be able to configure some kind of female connector from some other parts that might match the diameter of the power pins in the radio, and then put some shrink tubing over them...Not an elegant solution, but it might get you going...Another point you have to consider is that the radio is very old, and I know mine started having trouble with the segments of the display tubes going out, so it would be wise to get it up and running any way you could so you could see what you have...
   In its day, it was a very nice radio...GOOD LUCK...BOB
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W9GB
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Posts: 2626




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« Reply #2 on: March 20, 2013, 06:13:13 PM »

Quote from: FloridaMarine
I recently acquired a Kenwood TR-7400A...missing a power cord.
Kenwood TR-7400A Owner's Manual (PDF)
http://buckeyejeeps.com/radio/docs/manuals/TR-7400UsersManual.pdf

This connector was a 1970s Japanese design and is available from the Eastern Asia mfg.
It was used for Asian soldering stations, DC power and 3+ pin versions for microphones.
LKG Industries (address below) imports these connectors to USA from Japan,
as well as a cheaper supplier from Taiwan/China.

PHILMORE-Datek Catalog
http://www.philmore-datak.com/mc/Page%2054.pdf

Florida Electronics Parts Dealers / Distributors
http://www.philmore-datak.com/flordsl.html

LKG Industries, Inc.
dba Philmore Mfg./Datak/Carter Craft/Pfanstiehl
3660 Publishers Drive
Rockford IL 61109
http://www.philmore-datak.com/
Phone: 815/874-2301    
Fax: 815/874-2896
Email: sales-lkgindustries@t6b.com

==
CHECK with AES Orlando -- they may have it in stock.

Ken's Electronics in Western Michigan usually has this power connector, in stock.
==
Unless you purchase a pre-made cable set -- this is a DIY Cable build.
Radio talking skills do not mean good shop or cable fabrication (soldering skills).

For DIY ABSOLUTELY CHECK YOUR DC WIRING (RED for + ; BLACK for -) when building this up.
Easy way to damage a nice working radio !!
« Last Edit: March 20, 2013, 06:47:55 PM by W9GB » Logged
W9GB
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Posts: 2626




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« Reply #3 on: March 20, 2013, 06:35:30 PM »

Second Note:

Does this TR-7400A have a CTCSS encoder installed for FM repeater usage?
http://www.universal-radio.com/catalog/fm_txvrs/tr7400a.html

ComSpec SS-64 is an after-market add-on.
ComSpec has been offering these add-on for the commercial land-mobile,
government/military, and amateur users since 1970.


The CTCSS boards from ComSpec are very inexpensive ($28.95 USD)
and I routinely see these used at hamfests/flea markets for a few almost same as new!
http://www.com-spec.com/ss64.htm

COM-SPEC Detailed Directions for SS-64 installation in the Kenwood TR-7400A
http://www.com-spec.com/insheet/tr7400a.pdf

The most common place to connect the SS-64 output is just prior to the modulation stage of the FM transmitter.
Typical connection would be to the connections would be to the center of the deviation pot. to the varactor diode in the modulator circuit, or to the manufacturer’s suggested connection point.
This connection point can vary from radio to radio.
DO NOT connect the SS-64 CTCSS Output to the Microphone Input as the microphone audio stages will distort and attenuate (filter out) the CTCSS signal.
« Last Edit: March 20, 2013, 06:40:07 PM by W9GB » Logged
FLORIDAMARINE
Member

Posts: 4




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« Reply #4 on: March 21, 2013, 06:07:46 PM »

Thanks for all the replies...

So I will cobble something together, ensuring my polarity is correct with an inline fuse...and keep looking!

The radio came from an estate sale and the folks are looking for the power cable for me.  It had such great reviews (while long in the tooth) that I figured it would be a good 2M radio for my son and I to start with.  I've been looking at antenna next and a tone board.  Its all greek to me so far, I am used to firing up a radio, doing a crypto fill, ensuring I have a hop set and going on the and running the net - not this!

More interested in the time spent with my son one on one and building up some radios and getting our licenses then anything else.

I work insane hours and we hunt together...but you don't get to talk or just "do stuff" together which is what I hope the radio hobby will do.

Thanks!

Sean
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FLORIDAMARINE
Member

Posts: 4




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« Reply #5 on: March 21, 2013, 06:10:48 PM »

I offer a qualified...  I have NO clue!  I know it has no tone board, was promised to work and looks sound - as in it was well taken care of.  You've given me some homework however!

Thanks W9GB!

Second Note:

Does this TR-7400A have a CTCSS encoder installed for FM repeater usage?
http://www.universal-radio.com/catalog/fm_txvrs/tr7400a.html

ComSpec SS-64 is an after-market add-on.
ComSpec has been offering these add-on for the commercial land-mobile,
government/military, and amateur users since 1970.


The CTCSS boards from ComSpec are very inexpensive ($28.95 USD)
and I routinely see these used at hamfests/flea markets for a few almost same as new!
http://www.com-spec.com/ss64.htm

COM-SPEC Detailed Directions for SS-64 installation in the Kenwood TR-7400A
http://www.com-spec.com/insheet/tr7400a.pdf

The most common place to connect the SS-64 output is just prior to the modulation stage of the FM transmitter.
Typical connection would be to the connections would be to the center of the deviation pot. to the varactor diode in the modulator circuit, or to the manufacturer’s suggested connection point.
This connection point can vary from radio to radio.
DO NOT connect the SS-64 CTCSS Output to the Microphone Input as the microphone audio stages will distort and attenuate (filter out) the CTCSS signal.

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W9GB
Member

Posts: 2626




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« Reply #6 on: March 21, 2013, 08:24:01 PM »

There are 4 factory Service Bulletins (1977-1979) for the Kenwood TR-7400A.
http://www.kenwoodusa.com/support/ama_radios/#_

Kenwood TR-7400A Service Manual
http://www.vk4yeh.com/downloads/TR-7400_Service_Manual.pdf
« Last Edit: March 21, 2013, 08:28:13 PM by W9GB » Logged
W9GB
Member

Posts: 2626




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« Reply #7 on: March 22, 2013, 03:41:31 PM »

CQRADIOSUPPLY, an eBay reseller since 2003 based in El Dorado Hills, California,
sells this Kenwood TR-7400A power connector on eBay.

Auction # 400184600498 ; $7.45 plus shipping costs.
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K0BT
Member

Posts: 190




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« Reply #8 on: March 22, 2013, 11:24:11 PM »

Sean,

PM me with your address and I'll mail you a connector.  I've had a used one in my junk box for years and don't need it.

Bob
K0BT
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K5LXP
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Posts: 4507


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« Reply #9 on: March 23, 2013, 06:58:50 AM »

If it works it works, but PL is definitely an issue.  The original PL deck optionally available for that rig was a pot adjustable oscillator which won't cut it today.  A com-spec deck can be installed but they're adjusted with a DIP switch, so changing that isn't terribly convenient if multiple tones are used in your area.  You will often see radios from that era at hamfests either with a hole cut in the case to access the DIP switch, or a row of toggle switches sticking out somewhere.

I have a buddy that still uses a 7400 as local simplex chat channel radio - no PL required.  I have an even older crystal 2M rig I keep in the garage for the same purpose.  If you end up getting more involved in the hobby I would recommend buying something newer with memories and built in PL.


Mark K5LXP
Albuquerque, NM
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W9GB
Member

Posts: 2626




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« Reply #10 on: March 24, 2013, 06:36:56 AM »

Quote from: K5LXP
If you end up getting more involved in the hobby I would recommend buying something newer with memories and built in PL.
Mark,

Ironically, many of the new dual-band FM transceivers have POOR selectivity in The INTERMOD ALLEYS of city and urban areas.  Most new ones do not handle skyscraper alleys, interstate RF around weight stations and some toll-road transponder systems.
The Kenwood TR-7400 as well as Icom radios from this 1970s era are very well built (more like LMR units).

w9gb
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K8AXW
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Posts: 3902




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« Reply #11 on: March 24, 2013, 10:09:49 AM »

Sean:  You've been offered a cable.... grab it!  However, when all is said and done you're going to have a radio that your son can listen with....but that's about it since it doesn't have a PL board installed.

Using an external PL board, as suggested, is a real pain in the keester.  I respectfully suggest you buy a new radio.  The prices on these type radios is as low as I've ever seen them. 

I think, considering your work schedule, this would be the best bet for you and your son.  I'd also stay away from eBay because that might be another can of worms.

(My son is a Lt. Col. also and so I'm familiar with his lack of free time for his wife and 3 kids) 

Thank your for your service.  Semper Fi
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FLORIDAMARINE
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Posts: 4




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« Reply #12 on: November 23, 2013, 09:05:06 AM »

Sorry I let this drop!

Work went nuts right about the time I was posting this, and then in May I decided to retire after 24 years of service to our great nation.

SO...  I am back to getting this radio set up, and dusting off my books to study for my license.

I retire the 1st of Dec - and have been basically hunting, and hunting for a job.  The deer hunting more successful so far!

Thanks for all the replies!!

Sean
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W9GB
Member

Posts: 2626




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« Reply #13 on: November 24, 2013, 05:22:09 AM »

Surplus Sales (Omaha, Nebraska)
http://www.surplussales.com/connectors/Microphone-2.html

MCM Electronics (Springboro, Ohio)
http://www.mcmelectronics.com/browse/Microphone%20Connectors/0000000658

Vetco (Bellevue, Washington)
http://www.vetco.net/catalog/product_info.php?products_id=6547

« Last Edit: November 24, 2013, 05:25:35 AM by W9GB » Logged
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