Converting a jap import car radio

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Hi there,

I have just bought a jap import car and it has a Kenwood DPX-440 cd player
( 2 din )

This model seems to have been sold in the USA as well as Japan.

Does anyone know if these can be converted from 76MHz - 90MHz to 88MHz -
108MHz ( I do not want to use a band expander )

There may be a diode that needs to be moves ( or a wire link )

If anyone can sed any light I would be great  ( otherwise I will have to
pull it out an suck it and see )

Option is to change it with a new one but I am a little broke at the moment.

Cheers

John




Re: Converting a jap import car radio



"jdm" <

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** Don't all you kiwis know about these:

http://www.eforsale.co.nz/fm-band-expander-nissan-plug-xidp46024.html




........  Phil



Re: Converting a jap import car radio


Hi Phil,

Yes I know about band expanders but I don't want to use one.

John
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    I just downloaded the DPX-440 manual from the Kenwood USA website at
http://www.kenwoodusa.com/support/simple.aspx?men=2&M269 %
    It says the FM frequency range is 87.9 - 107.9MHz in 200kHz steps
and doesn't mention anything about the 76 - 90MHz band.
    This is very strange...

Bob



Re: Converting a jap import car radio



"Bob Parker"

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**  Wake up,  Bob  -   the OP has the Japanese version.

" Jap Import "  =  kiwi jargon for a vehicle that comes ( second hand )
direct from Japan to NZ.

Never heard about how hard it is to get a vehicle re- registered in Japan
that is over 4 years old ??

Most are sent to the wreckers.





.......  Phil





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    You're right - I wasn't paying much attention. Yeah, I've been told
about the Japanese flogging their hardly-used cars to NZ and other places.
    Kenwood don't have the most user-friendly websites. The only one I
found where I could easily download the manual was the US one.
    I sorta expected that there might be a tiny switch on the back or
similar to change FM frequency bands, but I can't see anything in the
.pdf manual.


Bob


Re: Converting a jap import car radio



"Bob Parker"

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**  Such a switch cannot do the job that is needed.

A band up shift of nearly 20 MHz  requires the RF stages to be retuned   -
likely with different coils and cap values.

Merely re programming the local oscillator frequencies on the PPL is not
enough.




......   Phil





Re: Converting a jap import car radio


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    I'm the first to admit that I'm not familiar with car entertainment
systems.
    I just didn't think it made much sense to have two different
versions of the same unit built to cover different FM bands with exactly
the same model number, unless it was the same unit with some kind of
electronic band switching like maybe PIN diode switching of the
front-end tuning components.
    Like I said, I'm ignorant about what's out there in car systems
these days.


Re: Converting a jap import car radio


Thanks Bob,

I did not try the US site, I just tried the Japanese site.

Hopefully this will be able to be converted, I remember as an apprentice
converting a lot of home stereos for a chain store, they imported them with
the wrong band, I just had to move a diode and everything was fine.

Thanks

John
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Re: Converting a jap import car radio


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    After thinking for a few moments, I seemed to remember that
microcontroller-controlled receivers have varactor tuning of the front
end as well as a PLL for frequency control. The micro just needs to be
told which band to use, via a menu option, diode, link or a switch.
    I looked around but couldn't find a schematic. I hope you can do
better. :-)

Bob



Re: Converting a jap import car radio



"Bob Parker"

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** Varactor tuning is not so simple.

It has to cover both RF and local oscillator tuning ranges, which must track
each other quite closely in an FM receiver -  as the operating band is only
250 kHz wide.

Typically requires a DC control voltage of 2 to 30 volts to cover the 88 -
108 MHz band.


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** That is a BIG assumption in relation to Japanese, local model, car
radios.

No need for those radios to have band compatibility built in.



.......   Phil




Re: Converting a jap import car radio


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     I thought (being from an RF background), that most of the
selectivity in a receiver is in the IF not the front end, and as long as
the front end's selective enough to reject image frequencies, there's no
real problem?



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    My point is that it seems ridiculous for there to be two variants of
the same receiver covering different band segments, with *exactly* the
same model number ... not even a suffix to indicate which is which ...
unless that same unit can handle both band segments by being told which
one to use.


Bob

Re: Converting a jap import car radio



"Bob Parker"
 Phil Allison wrote:
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** You thought wrong.

Good RF pre-selection is essential for any high performance AM or FM
broadcast receiver.

The same does not apply to narrow band,  two-way radio systems which you may
well be thinking of.



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** You have no reason to make that assumption either.

    The 76-90 MHz version is sold only in Japan.





.......   Phil





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    So what you're saying is that they manufacture two quite different
versions of the same unit, and give them identical type numbers so
there's no way of telling them apart?
    I'm only asking because I don't recall seeing that happen before...

Bob


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"Bob Parker"
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**  Don't be stupid.

You have not seen the Jap version nor it's manual to say any such thing.

Being sold ONLY in Japan suggests the unit will be marked and the manual
written in Japanese characters.





........  Phil






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    I was simply asking a question not making a statement, because I
don't remember seeing anything like that before.
    I'm trying to learn something from your experience ... which is what
newsgroups are supposed to be about.


Bob

Re: Converting a jap import car radio



"Bob Parker"
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**  That Q contained an unwarranted assumption that was all yours.






.......  Phil




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    It's over 10 years since I got out of doing repairs full time, but
now I remember that Yamaha and others do have different variants of the
same model with the same type number, for different markets.
    I withdraw some of my earlier comments. :-)


Bob


Re: Converting a jap import car radio



"Bob Parker"
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**  If you were doing instrument amp repairs  -  you would have come across
the very popular " Roland JC120 " combo amp  ( JC  =  Jazz-Chorus).

Been in production since 1975s and still available with virtually unchanged
appearance.

See:

http://www.rolandus.com/products/productdetails.aspx?ObjectId24%9&ParentId57 %


Internally, there are at least 10 distinct versions of the JC120, each with
its own schematic.

Only way to know which schem to order is by the serial number on the
particular amp.

Naturally, guitar players falsely imagine they are all just the same.

Just what Roland wants them to think.




......  Phil





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    Now that you mention it, I vaguely remember getting caught by some
Yamaha amps with different boards, depending on the serial number. I'd
forgotten all that until now. I must be getting old....

Bob

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