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