[aprssig] Kenwood TR-7730 backup battery?

Greg D ko6th.greg at gmail.com
Sun Apr 21 02:14:41 CDT 2013


Ah, good find, and an interesting idea.  But, the article is a "reprint" 
from a 73 Magazine article from 1981 (fine print at the bottom), and I 
can't find KA1LR on QRZ.com.  I don't do facebooking, so the email link 
didn't work either.  {sigh}

Nice write-up on the rig, however.  I picked it up at a club "white 
elephant" sale for a couple of bucks, condition unknown, so it looks 
like I did ok.

Greg  KO6TH


Steve Noskowicz wrote:
>
> Try KA1LR.  Perhaps he knows something.  His review os only a year old:
>
>    http://www.radioaficion.com/HamNews/reviews/kenwood/9440-tr-7730-review-by-ka1lr.html
>
>
> 73, Steve, K9DCI  USN (Vet)  MOT (Ret)  Ham (Yet)
>
>
> --- On Sat, 4/20/13, Steve Noskowicz<noskosteve at yahoo.com>  wrote:
>
>> From: Steve Noskowicz<noskosteve at yahoo.com>
>> Subject: Re: [aprssig] Kenwood TR-7730 backup battery?
>> To: "TAPR APRS Mailing List"<aprssig at tapr.org>
>> Date: Saturday, April 20, 2013, 6:14 PM
>>
>>
>> I think that stuff is all poart of the ham's mod.
>>
>> 1 -  I can't resolve why it looks like a 4 pin
>> connector.
>>
>>     I suspect:
>>
>> 2 -  the original circuit had nothing to do with the
>> main power input.  He did that mod so he could use some
>> batteries instead of the external TK-1 power widgit and
>> wanted the main power to keep it charged.  Nice idea.
>>    I think there is another path from the DC power input
>> to the micro processor memory supply, but am too lazy too
>> try to trace it out.  This is becauese that schematic
>> looks like the lines are all hand drawn going between DC
>> input and the memory backup connector..  Dunno.
>>
>>
>> 3 - He added the 4k resistor deeper in the schematic along
>> that backup input line .  Don't know why because it
>> appears to say 6V by the backup connector.  Perhaps the
>> TK-1 is a 12 volt wall wart and he wants to frop more, so
>> increased that resistance......?
>>
>> Gud Luk.
>>
>>
>> 73, Steve, K9DCI
>>
>>
>> --- On Sat, 4/20/13, Greg D<ko6th.greg at gmail.com>
>> wrote:
>>
>>
>>> Thanks for the link to the schematic;
>>> Google wasn't quite so friendly to
>>> me this time.  I had found the operating manual, and
>>> the battery part
>>> number, but no details like voltage or pinout.
>>>
>>> I see the mod you are referring to.  The battery
>>> appears to get charged
>>> from the mains, through a diode and resistor.  1.2v x
>>> 6, it says, so
>>> 7.2v.  That's pretty high for a memory backup
>> battery,
>>> no?
>>>
>>> I'm guessing the box to the left is probably the 3-pin
>>> connector, though
>>> it looks to have spots for 4 pins.  One pin for
>> ground,
>>> one to the mains
>>> for charging, and one out to the circuitry.  So, the
>>> charge limiting and
>>> such was originally in the battery product?  Odd. 
>>> But if so, then the
>>> big question is the black smudge above.  What is
>>> it?  What is it covering?
>>>
>>> If I follow what appears to be the output wire, it
>> looks
>>> like it goes to
>>> some sort of adjustable voltage regulator.  Again,
>>> odd.  Why have an
>>> adjustable regulator for a processor memory backup? 
>>> There's another mod
>>> there ("4k", presumably a resistor), so it's probably
>>> related to the
>>> other battery mod.
>>>
>>> The final odd thing is that I don't see where that the
>>> backup battery
>>> supply would be replaced with mains power in the
>> original
>>> design, if as
>>> I have it, the battery is removed.  That regulator
>>> circuit isn't
>>> diode-driven by mains, for example.  Unless it's
>> under
>>> that smudge.
>>>
>>> Still searching...
>>>
>>> Thanks for the help,
>>>
>>> Greg  KO6TH
>>>
>>>
>>>
>>> Steve Noskowicz wrote:
>>>> The link in the upper left of the page below has
>> a
>>> slightly better schematic.  It is in the upper right
>> of
>>> the schematic right at the power input, but someone
>> added a
>>> mod and the otiginal is obscured.  However, it
>> appears
>>> you may be able to ohm it out.
>>>> One pin is ground and it may be that the other
>> three
>>> are plus, but it's hard to tell.  A better schenatic
>>> will tell.
>>>> http://elektronicsstock.blogspot.com/search/label/TR%207730#!/2011/04/schema-kenwood-tr-7730.html
>>>>
>>>>
>>>> 73, Steve, K9DCI  USN (Vet)  MOT (Ret)
>>> Ham (Yet)
>>>> --- On Sat, 4/20/13, Steve Noskowicz<noskosteve at yahoo.com>
>>> wrote:
>>>>> From: Steve Noskowicz<noskosteve at yahoo.com>
>>>>> Subject: Re: [aprssig] Kenwood TR-7730 backup
>>> battery?
>>>>> To: "TAPR APRS Mailing List"<aprssig at tapr.org>
>>>>> Date: Saturday, April 20, 2013, 10:43 AM
>>>>>
>>>>>
>>>>> Mods.dk probably has it.
>>>>> Also...
>>>>> Please remember that Google is your friend:
>>>>>
>>>>>      try Google "kenwood tr-7730 service
>>> manual"
>>>>> BUT BE CAREFUL.  On some sites the big,
>>> obvious
>>>>> "DOWNLOAD" buttion is for something else.
>> The
>>> real
>>>>> download is in "fine print" somewhere else:
>>>>> e.g. this operator's manual:  http://elektrotanya.com/kenwood_tr-7730_sm.pdf/download.html
>>>>>
>>>>> Poor resolution Schematic:
>>>>> http://elektronicsstock.blogspot.com/2011/04/schema-kenwood-tr-7730.html#!/2011/04/schema-kenwood-tr-7730.html
>>>>>
>>>>>
>>>>>
>>>>>
>>>>>
>>>>> 73, Steve, K9DCI  USN (Vet)  MOT
>>> (Ret)  Ham
>>>>> (Yet)
>>>>>
>>>>> Up to date APRS Beginner Guide - updated
>> Oct-2011
>>>>>      http://K9DCI.home.comcast.net
>>>>>        Click 'APRS Beginner INFO'
>>> under Contact
>>>>> Manage Radio Memories with an Excel
>> Spreadsheet !
>>>>> Click to tune. Click to capture Radio freq.
>>>>> All Memories on one page. Cut, Copy, Paste,
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>>>
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>>>>> Tones!
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>>>>> A version for the D7 is in the works.
>>>>>
>>>>> More Details, Features and Downloads at:
>>>>>      http://k9dci.home.comcast.net/
>>>>>
>>>>>
>>>>> --- On Fri, 4/19/13, Greg D<ko6th.greg at gmail.com>
>>>>> wrote:
>>>>>
>>>>>> From: Greg D<ko6th.greg at gmail.com>
>>>>>> Subject: [aprssig] Kenwood TR-7730 backup
>>> battery?
>>>>>> To: "TAPR APRS Mailing List"<aprssig at tapr.org>
>>>>>> Date: Friday, April 19, 2013, 10:54 PM
>>>>>> Hi folks,
>>>>>>
>>>>>> My packet station and iGate runs on an old
>> but
>>> quite
>>>>>> serviceable Kenwood TR-7730.  The rig
>> has
>>> a connector
>>>>>> in the back for a backup battery, but none
>> is
>>> present,
>>>>> so
>>>>>> any momentary glitch in power send it back
>> to
>>>>>> defaults.  I have not been able to find
>> a
>>> battery,
>>>>> nor
>>>>>> the pin-out and specs to fashion one of
>> my
>>> own.
>>>>>> There appear to be 3 pins in a triangle
>>> formation.
>>>>>> Anybody know what the spec is?
>>>>>>
>>>>>> Thanks,
>>>>>>
>>>>>> Greg  KO6TH
>>>>>>
>>>>>>
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