how to make an FM band expander?
Darren
I live in New Zealand, i have a jap import, the stereo wont go ova 90FM how
do i make a band expander so i can pick up ova 90FM?
thanks
Bob Wilson
>
>Hi,
>I live in New Zealand, i have a jap import, the stereo wont go ova 90FM how
>do i make a band expander so i can pick up ova 90FM?
Open up the tuner and retune it so it will reach "ova 90FH".
Bob.
Darren
what do i turn.............?
Bob Wilson <rfwi...@intergate.nospam.bc.ca> wrote in message
news:trd71ud...@corp.supernews.com...
John Woodgate
(in <9p69bo$ann$1...@lust.ihug.co.nz>) about 'how to make an FM band
expander?', on Sun, 30 Sep 2001:
YOU CAN'T. You will wreck it.
I suppose it covers 76 to 90 MHz, the Japanese FM band? What you need is
a 'frequency converter', which goes between your FM antenna (aerial) and
the tuner. This contains an oscillator and a mixer, and converts the
incoming FM signal in the band 87.5 to 104 MHz (is that right for NZ?)
to lower frequencies. However, the band 87.5 to 104 MHz is wider than
the band 76 to 90 MHz, so you can't cover the whole band with one
oscillator frequency.
To keep things simple, I'll assume that doesn't matter, because you
don't want to receive stations at both the lowest and the highest
frequencies. To cover 88 to 102 MHz, you need an oscillator at either
88-76 or 88+76 MHz, i.e. 12 or 164 MHz.
The usual way that radio amateurs and hobbyists build this type of
converter is to get an FM 'tuning head' from an electronics supplier,
and modify it. The tuning head includes the oscillator and mixer
circuits, but needs considerable changes. You need quite a bit of skill
to work on circuits operating at these frequencies. I suggest you try to
find a local electronics person to help you.
--
Regards, John Woodgate, OOO - Own Opinions Only. http://www.jmwa.demon.co.uk
Eat mink and be dreary!
Phil Allison
Darren <da...@hotmail.com> wrote in message
news:9p5pgv$v7l$1...@lust.ihug.co.nz...
I take it the "jap import" is your car and the stereo is a factory
installed unit.
If it has digital tuning and display etc then forget any modifications.
You can buy a converter to go between the car stereo and the antenna. It
will down convert the signal to the existing band with some parts maybe
missing. I have seen them advertised but can't remember where.
Ask around any places that sell or repair car stereo, someone is bound to
know a source.
Regards, Phil
Gary Tait, Very Real
Just convert 90 to 104 to 76 to 90, and bypass the convertor to tune
below 90.
--
Gary Tait,VE3VBF Homepage: http://www.primeline.net/~tait
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Phil Allison
John Woodgate <j...@jmwa.demon.co.uk> wrote in message
news:P+M25IAQ...@jmwa.demon.co.uk...
> incoming FM signal in the band 87.5 to 104 MHz (is that right for NZ?)
Its actually 88 to 108 Mhz, same FM band as in USA and Australia.
Regards, Phil
John Woodgate
<ta...@primeline.net> wrote (in <3BB7311F...@primeline.net>) about
'how to make an FM band expander?', on Sun, 30 Sep 2001:
>below 90.
You could, but it's not very convenient in the home.
Richard Harrison
"How do I make a band expander so I can pick up ova 90FM?"
John Woodgate indicates a band extending from 76 to 90 MHz in Japan.
That`s only 14 MHz of spectrum and the band "daz59" is interested in
covers 20 MHz of spectrum. Two bands are needed in a converter to cover
the 88 to 108 MHz band using the 76 to 90MHz receiver as a tuneable IF
sysem.
"daz59" could use 12 MHz and 18 MHz as local oscillator (LO)
frequencies. A power switch could be used to select one oscillator at a
time. Complete 4-pin crystal-controlled oscillators are available, often
at very low surplus prices. Or, simple oscillators can be made from
scratch.
The 12 MHz LO would allow tuning from 88 MHz to 102 MHz with the 76 to
90 MHz dial.
The 18 MHz LO would allow tuning from 94 MHz to 108 Mhz with the 76 to
90 MHz dial.
A bandpass filter for the 88 to 108 MHz range would help ahead of the
mixer of "daz59"`s choice. The mixer`s output needs to allow passage of
76 to 90 MHz.
Best regards, Richard Harrison, KB5WZI
Graeme Zimmer
> I suppose it covers 76 to 90 MHz, the Japanese FM band? What you need is
> a 'frequency converter', which goes between your FM antenna (aerial) and
> the tuner. This contains an oscillator and a mixer, and converts the
> incoming FM signal in the band 87.5 to 104 MHz (is that right for NZ?)
> to lower frequencies. However, the band 87.5 to 104 MHz is wider than
> the band 76 to 90 MHz, so you can't cover the whole band with one
> oscillator frequency.
At one time I re-tuned a Japanese car radio to cover the normal (Australian)
FM Band.
It did work, but it always sounded badly distorted on highly deviated
signals.
I came to the conclusion that the Japanese FM BC band uses a narrower
bandwidth
(e.g. deviation).
(I can't remember whether the Stereo was compatible or not.........)
........................ Zim
Gary Tait, Very Real
That means you would have to change IF components for a wider one.
If it's a PLL tuned radio, you could play with the diode option matrix
on the micro controller. You might have to re-tune or replace
the front end though.
John Woodgate
<gzi...@optushome.com.au> wrote (in <zPWt7.17028$Tv6....@news1.rdc1.n
sw.optushome.com.au>) about 'how to make an FM band expander?', on Mon,
1 Oct 2001:
>It did work, but it always sounded badly distorted on highly deviated
>signals.
>
>I came to the conclusion that the Japanese FM BC band uses a narrower
>bandwidth
>(e.g. deviation).
...or the Australian stations over-deviate?
Phil Allison
Oh no John, everyone knows the Japanese are far more devious than
Australians!!!
Regards, Phil
Phil Allison
Graeme Zimmer <gzi...@optushome.com.au> wrote in message news:zPWt7.17028>
>
> At one time I re-tuned a Japanese car radio to cover the normal
(Australian)
> FM Band.
>
> It did work, but it always sounded badly distorted on highly deviated
> signals.
>
> I came to the conclusion that the Japanese FM BC band uses a narrower
> bandwidth
> (e.g. deviation).
If have heard 76-90 MHz FM tuners made for the Japanese market working
just fine in Australia and down converters were once available so I don't
believe there is a problem with bandwidth.
However, you can have the receiver's local oscillator tuned such that
second harmonic output mixes with a second harmonic of the wanted FM signal
(generated in the tuner) and the two produce a difference product back at
10.7 Mhz.
This 10.7 MHz product will have twice the deviation of the original
signal and distort on loud passages.
I had this happen to me when I was playing around with FM receivers.
Regards, Phil
Graeme Zimmer
> If have heard 76-90 MHz FM tuners made for the Japanese market working
> just fine in Australia and down converters were once available so I don't
> believe there is a problem with bandwidth.
I don't have my WRTVHB handy, else I'd go look it up. Anybody ?
> However, you can have the receiver's local oscillator tuned such that
> second harmonic output mixes with a second harmonic of the wanted FM
signal
> (generated in the tuner) and the two produce a difference product back at
> 10.7 Mhz.
> This 10.7 MHz product will have twice the deviation of the original
> signal and distort on loud passages.
Yes, that certainly is/was a possibility. It would be worth another try.
There are oodles of ex JA car radios hanging around in the car
importer/wreckers....
............................... Zim