heya fellas,

I recently took apart an old radio. My interest in radios has been growing for the past few months. The only problem is that I have no where near the funds required to set myself up with even a decent portable radio. Anyway, back to this radio. It was probably made in the late 80's to early 90's. It says its a Bluapunkt Sabre 90... Does this mean anything to you guys?

It is almost a standard radio, except that it can handle SW. Now, when I opened it up, I noticed 3 coils of wire wrapped around some sort of a tube. In my brain, im think that these 3 coils are for the 3 different frequency bands! So, now this gets me thinking, maybe I can make some different coils, and so change the frequency band? Is it that simple, or is there something more to it? I really want to listen in on our nearby airport at 121.9MHz... I think.

Are there any websites that I can visit to help aswell.

Kind regards,
Patrick

Patrick Rimbault wrote:


It is almost a standard radio, except that it can handle SW. Now, when
I opened it up, I noticed 3 coils of wire wrapped around some sort of a
tube. In my brain, im think that these 3 coils are for the 3 different
frequency bands! So, now this gets me thinking, maybe I can make some
different coils, and so change the frequency band? Is it that simple,
or is there something more to it? I really want to listen in on our
nearby airport at 121.9MHz... I think.

Are there any websites that I can visit to help aswell.

Kind regards,
Patrick

Sounds like you are describing the ferrite rod internal antenna. The
three coils might be LW, MW or 1-2 shortwave bands.

These are actually coils for the antenna input stage for those lower
frequency bands. The equivalent "FM" coil is likely going to be a
little tiny thing of several turns mounted on a circuit board.

Thats only half the story. There's also a set of oscillator coils for
each band....maybe in little square cans or out in the open.

The quick answer is no, this isn't a simple modification. Many of us
(me included) have done such things so I can't say its not possible
but you would be much farther ahead maybe building a little Aircraft
band converter kit of something of that nature.

Just my 2c

-Bill

On Thu, 14 May 2009 18:49:39 -0400, Bill M wrote:

Patrick Rimbault wrote:


It is almost a standard radio, except that it can handle SW. Now, when
I opened it up, I noticed 3 coils of wire wrapped around some sort of a
tube. In my brain, im think that these 3 coils are for the 3 different
frequency bands! So, now this gets me thinking, maybe I can make some
different coils, and so change the frequency band? Is it that simple,
or is there something more to it? I really want to listen in on our
nearby airport at 121.9MHz... I think.

Are there any websites that I can visit to help aswell.

Kind regards,
Patrick

Sounds like you are describing the ferrite rod internal antenna. The
three coils might be LW, MW or 1-2 shortwave bands.

These are actually coils for the antenna input stage for those lower
frequency bands. The equivalent "FM" coil is likely going to be a
little tiny thing of several turns mounted on a circuit board.

Thats only half the story. There's also a set of oscillator coils for
each band....maybe in little square cans or out in the open.

The quick answer is no, this isn't a simple modification. Many of us
(me included) have done such things so I can't say its not possible
but you would be much farther ahead maybe building a little Aircraft
band converter kit of something of that nature.

Just my 2c

-Bill




Also, if I remember correctly, aircraft use AM in the 108-136 MHz range.
So modifying the 88-108 MHz FM portion of the receiver wouldn't work.
And modifying one of the lower AM/SSB bands to work on VHF would be quite
a stretch.

.... Rich W2RG

Rich Griffiths wrote:


Also, if I remember correctly, aircraft use AM in the 108-136 MHz range.
So modifying the 88-108 MHz FM portion of the receiver wouldn't work.

Doesn't really matter much since you can slope tune it.

-B.

On Thu, 14 May 2009 19:25:30 -0400, Bill M wrote:

Rich Griffiths wrote:


Also, if I remember correctly, aircraft use AM in the 108-136 MHz
range. So modifying the 88-108 MHz FM portion of the receiver wouldn't
work.

Doesn't really matter much since you can slope tune it.

-B.

It's been a long time since I did it, but isn't slope detection for
receiving an FM signal using an AM receiver? This is the reverse
situation.

.... Rich

In article ,
Bill M wrote:

Also, if I remember correctly, aircraft use AM in the 108-136 MHz range.
So modifying the 88-108 MHz FM portion of the receiver wouldn't work.

Doesn't really matter much since you can slope tune it.

IIRC, slope tuning can be used to allow an AM receiver to demodulate
FM (albeit somewhat crudely).

Does it work in reverse? Can you offset-tune an FM receiver, and get
its discriminator to demodulate an AM carrier-and-sidebands?

Seems to me that this wouldn't necessarily work... the
huge-amounts-of-gain-and-then-clip-the-result architecture of an FM's
IF strip is going to equalize out the amplitude variations in the AM
signal pretty effectively, won't it?

--
Dave Platt AE6EO
Friends of Jade Warrior home page: http://www.radagast.org/jade-warrior
I do _not_ wish to receive unsolicited commercial email, and I will
boycott any company which has the gall to send me such ads!

On May 14, 8:24*pm, (Dave Platt) wrote:
In article ,
Bill M wrote:

Also, if I remember correctly, aircraft use AM in the 108-136 MHz range. *
So modifying the 88-108 MHz FM portion of the receiver wouldn't work. *
Doesn't really matter much since you can slope tune it.

IIRC, slope tuning can be used to allow an AM receiver to demodulate
FM (albeit somewhat crudely).

Does it work in reverse? *Can you offset-tune an FM receiver, and get
its discriminator to demodulate an AM carrier-and-sidebands?

Seems to me that this wouldn't necessarily work... the
huge-amounts-of-gain-and-then-clip-the-result architecture of an FM's
IF strip is going to equalize out the amplitude variations in the AM
signal pretty effectively, won't it?

--
Dave Platt * * * * * * * * * * * * * * * * * AE6EO
Friends of Jade Warrior home page: *http://www.radagast.org/jade-warrior
* I do _not_ wish to receive unsolicited commercial email, and I will
* * *boycott any company which has the gall to send me such ads!

If an FM radio has a decent amount of limiting forget about receiving
FM but if the limiting can be removed or it doesnt have too much you
can receive AM on an FM receiver thought it may be fairly distored but
it most likely will be copyable. For example I have an ICOM two meter
FM transceiver that will tune the VHF aircraft frequencies. Sorry
but I forget the model # at present I bought it about 15 years ago and
havent tused it in 10 years.


Jimmie

Hey OM:

Back that far they been using PLL for FM demod. Only because they
needed to demod stereo phase, at 15 some Khz. Find the slope in that
PLL and it'll detect AM. But most osc's in those things are only good
to 110Mhz, with 10.7 Mhz IF, that'll get you to 120.7Mhz You just
can't make the capacitance of the circuit go away with a coil.
If you are lucky the airport your near will be within 108 to 120.7 Mhz

You might as well just build a converter, like back in the day when FM
first came out they used a converter to take 88 to 108 MHz and put it
on the AM band. All you did was plug the box into the antenna of your
AM car radio and viola' FM and with a reverb you could even simulate
stereo. That was b4 8 track tape decks.

Heck I made a living making and selling a converter for police band
453Mhz to AM radio band you could actually tune 4 police channels in
the Detroit, MI USA area with the converter and any AM radio. We used
a CB crystal for the oscillator multiplied it up to 452 Mhz and viola'
police band on any AM radio. the converter was the size of a pack of
cigarettes.

This link will give you an idea now a days things are a lot easier:
http://tinyurl.com/qwk9pw

73 OM

de n8zu


On May 14, 8:41*pm, JIMMIE wrote:
On May 14, 8:24*pm, (Dave Platt) wrote:



In article ,
Bill M wrote:

Also, if I remember correctly, aircraft use AM in the 108-136 MHz range. *
So modifying the 88-108 MHz FM portion of the receiver wouldn't work.. *
Doesn't really matter much since you can slope tune it.

IIRC, slope tuning can be used to allow an AM receiver to demodulate
FM (albeit somewhat crudely).

Does it work in reverse? *Can you offset-tune an FM receiver, and get
its discriminator to demodulate an AM carrier-and-sidebands?

Seems to me that this wouldn't necessarily work... the
huge-amounts-of-gain-and-then-clip-the-result architecture of an FM's
IF strip is going to equalize out the amplitude variations in the AM
signal pretty effectively, won't it?

--
Dave Platt * * * * * * * * * * * * * * * * * AE6EO
Friends of Jade Warrior home page: *http://www.radagast.org/jade-warrior
* I do _not_ wish to receive unsolicited commercial email, and I will
* * *boycott any company which has the gall to send me such ads!

If an FM radio has a decent amount of limiting forget about receiving
FM but if the limiting can be removed or it doesnt have too much you
can receive AM on an FM receiver thought it may be fairly distored but
it most likely will be copyable. For example I have an ICOM two meter
FM *transceiver that *will tune the VHF aircraft frequencies. Sorry
but I forget the model # at present I bought it about 15 years ago and
havent tused it in 10 years.

Jimmie

On May 15, 12:32*am, raypsi wrote:
Hey OM:

Back that far they been using PLL for FM demod. Only because they
needed to demod stereo phase, at 15 some Khz. Find the slope in that
PLL and it'll detect AM. But most osc's in those things are only good
to 110Mhz, with 10.7 Mhz IF, *that'll get you to 120.7Mhz You just
can't make the capacitance of the circuit go away with a coil.
If you are lucky the airport your near will be within 108 to 120.7 Mhz

You might as well just build a converter, like back in the day when FM
first came out they used a converter to take 88 to 108 MHz and put it
on the AM *band. All you did was plug the box into the antenna of your
AM car radio and viola' FM and with a reverb you could even simulate
stereo. That was b4 8 track tape decks.

Heck I made a living making and selling a converter for police band
453Mhz to AM radio band you could actually tune 4 police channels in
the Detroit, MI USA area with the converter and any AM radio. We used
a CB crystal for the oscillator multiplied it up to 452 Mhz and viola'
police band on any AM radio. the converter was the size of a pack of
cigarettes.

This link will give you an idea now a days things are a lot easier:http://tinyurl.com/qwk9pw

73 OM

de n8zu

On May 14, 8:41*pm, JIMMIE wrote:



On May 14, 8:24*pm, (Dave Platt) wrote:

In article ,
Bill M wrote:

Also, if I remember correctly, aircraft use AM in the 108-136 MHz range. *
So modifying the 88-108 MHz FM portion of the receiver wouldn't work. *
Doesn't really matter much since you can slope tune it.

IIRC, slope tuning can be used to allow an AM receiver to demodulate
FM (albeit somewhat crudely).

Does it work in reverse? *Can you offset-tune an FM receiver, and get
its discriminator to demodulate an AM carrier-and-sidebands?

Seems to me that this wouldn't necessarily work... the
huge-amounts-of-gain-and-then-clip-the-result architecture of an FM's
IF strip is going to equalize out the amplitude variations in the AM
signal pretty effectively, won't it?

--
Dave Platt * * * * * * * * * * * * * * * * * AE6EO
Friends of Jade Warrior home page: *http://www.radagast.org/jade-warrior
* I do _not_ wish to receive unsolicited commercial email, and I will
* * *boycott any company which has the gall to send me such ads!

If an FM radio has a decent amount of limiting forget about receiving
FM but if the limiting can be removed or it doesnt have too much you
can receive AM on an FM receiver thought it may be fairly distored but
it most likely will be copyable. For example I have an ICOM two meter
FM *transceiver that *will tune the VHF aircraft frequencies. Sorry
but I forget the model # at present I bought it about 15 years ago and
havent tused it in 10 years.

Jimmie- Hide quoted text -

- Show quoted text -

I remember when those things were around. There was a group of my
friends who like to do a little street racing so we used it to keep up
with where the police were. We also used CB radio to talk to each
other. When we found out the police were on to us planing races on CB
we got where we would pass the mike around and pretend like we were
having a race and watch them run all over town. The things we had to
do back then to keep intertained.


Jimmie