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                              LFB 4 band digital shortwave converter
                              for cars and trucks.
 


 

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Shortwave
This is the name commonly given to broadcasts transmitted at frequencies higher than AM and lower
than TV channels 2- 13 and also lower than FM. What distiguishes shortwave bands from other
bands is their ability to propagate for very long distances ( intercontinentally most of the time).
This allows you to receive shortwave in ANY spot in the world , wherever you are.

Why a Converter?

As  telecommunications advance, cable and satellite television have become available in almost
any spot in our planet, making reception of shortwave broadcasts for obtaining news and
information at home unpractical for the vast majority of people except for some hobbyists and
experts who still enjoy this form of communication. But there are two uses of shortwave reception
which are still practical in our view.
First is portable use. It is still practical to throw in your portable shortwave receiver into your
luggage and listen to your news anyplace  in the world even if your hotel doesn't have CNN.
Second is mobile use. Although  shortwave is still considered the tradicional means of radio
broadcasting over long distances,  satellite broadcasting for vehicles has become available in
the US and has became an alternative to shortwave with better sound quality. An inconvenience
of satellite broadcasting is that  it is not free and won't  be so for the foreseeable future.
  Reception of shortwave broadcasts in automobiles has always
been associated by the general public and therefore by the radio industry, as a difficult proposition
for mobile listeners, partly due fading of stations, partly due to oscillator drift due to vehicle
motion in analog tuners and partly due to the inability of the installers to pay sufficient attention
to noise suppression which requires similar care as receiving weak AM stations.
     As a result of this, there are presently (year 2010) very limited options for receiving
shortwave broadcasts in an automobile.

The 1st option is installing a car stereo unit which includes one or more shortwave bands among
its options. To our knowledge there is only 1 option nowadays for obtaining a complete
shortwave car stereo unit:

Sony has  had  a line  of CD receivers  which includes  AM-FM and shortwave  for several years now
These CD players are among the least expensive and simplest of their complete line of CD receivers
and none include  USB input, Ipod,  Bluetooth,  or satellite radio. These shortwave models are available
in some places in Asia, Africa and South America and they cost around U$ 100.  Present models of these
CD receivers include CDX-GT290 and CDX-GT292 (Year 2010). Some recently outdated models but
some still available include CDX-GT260, CDX-GT360, CDX-GT270, CDX-GT272, CDX-GT370,
CDX-GT280, CDX-GT282, CDX-GT380 and may be some others. But as far as the shortwave tuner all
of them seem to have the same tuner (same bands,   band1(2940-7735), band2(9500-10140), band2
(11575-18135)(no mistake, no band3, see later).  IF's were in most of the units 10.7Mhz/450Khz but seem
 to have changed in CDX-GT290 to 25khz (????).  We bought one of them, the CDX-GT260 in a border
town between Brasil and Uruguay in 2008 where several free shops exist.
We purchased it for comparing it with our converter.  We will later comment on the result of the comparison
from the shortwave point of view , but needless to say Sony's CD receivers are good products.    

Some used obsolete products which include shortwave can be found in Ebay
Sony's (cassette receivers, previously obtainable from the Middle East).Becker's Mexico 2340 (cassette stereo, very expensive used to be available  at Mercedes Benz dealerships. )  Occasionally used units may be bought nowadays.Phillips DC 777 (used cassette stereo with good electronics and not so good plastic parts).

<>All of them are hard to get these days.

What about if you want a shortwave CD receiver  ?
If you can get hold of one  of the simple shortwave  CD receivers  available  in other continents,
you will be satisfied with one of the Sony units.
What about if you can't get hold of any of these units or you want other options in the CD receiver
as USB, ipod, bluetooth, or satellite radio ?
Then you have to look at the 2nd option , that is installing a shortwave converter together
with anyone of several hundred CD-AM-FM receivers available on the market with
every conceivable option available (with the exception of shortwave).

So , what are the advantages of a shortwave converter ?
Well, actually there are no advantages when compared to the ideal carstereo you wish
you had (AM, FM, Shortwave, TV, DSP, cassette, CD , DVD, RDS, MP3,  USB , card reader,
ipod,  Bluetoth  etc. etc. ).
But as you live in the real world where you can't have all you want , then using a
shortwave converter is the best compromise for listening to shortwave on your car and using
all other options the market offers you for sound on your automobile.
 

So , again, is there any advantage on  choosing a shortwave converter as compared to
"Let's say a Sony CD from Asia" , for example ?

Assuming that  we are talking about a digitally synthesized converter as LFB is,
then we can say that at the frequencies where both systems receive, the performance of  both
systems  is more than adequate to cope with on the road shortwave listening.

We tested the Sony CDX-GT260 vs. the LFB converter


Although we might be biased toward the LFB , we will try to be as fair as possible, not denying that
Sony still makes good  shortwave  car receivers.

We tested  the  Sony  CDX- GT260  together  with the LFB converter  connected as follows:

1)  CDX-GT260  for shortwave tuning  connected to the antenna throuth the converter in
     "straight wire"

2)  CDX-GT260   for AM tuning   connected to the  antenna  throught the converter and operating as
     a  shortwave converter.

We tested mainly  with the car parked and no engine.

Oscillator stability was excellent in both 1) and 2)  as can be expexted in digitally synthesized systems
 
Selectivity was about the same.  This happened mainly because the IF filter  in the Sony is the same
in shortwave and in AM  . But if the AM receiver has a narrower band  then 2) setup will be more selective.

<>System gain :   1)  has less gain than 2).   There is an inconvenience with 1).   When  you switch  from  FM to
shortwave bands  you have  to increase the volume significantly to listen to any station.   But after  you go
back to FM AM or CD, you have to lower your volume  fast, otherwise  volume will be unbearable  with
a chance  of ruining your speakers. In 2)  when changing from  shortwave (strong stations) to  AM FM  or
viceversa, there is no need to adjust the volume.

 Background noise :  When listening to nothing then 1) was a little quieter than 2)

 Probably  1) has double conversion while 2) has triple conversion.  The more conversions , the more image
 rejection  and more noise .

When listening to  normal  on the road listenable stations, noise was about the same.

One thing we didn't like in 1)  is that  one station can show in 2 adjacent  slots.
For example the BBC World Service shows up at 15400 Khz and also at 15405Khz.with almost equal strength.
The true frequency is 15400 khz. This has to do with a wide shortwave  IF filter or a misadjusted  oscillator
In 2) any station showing at a certain frequency might show 5 khz above,  but with significant  attenuation.

But there are some secondary considerations worth mentioning:
When we first start searching for stations on the  CDX-GT260,  we are amazed by the size of the  search.
It seems like outer space when you find a planet every once and then. Sony receiver has 2 bands:  1st from
 2940 to 7735 khz. and 2nd from   9500 to 18135 khz, with a big hole  between 10140 and 11575 khz..

If we step up manually 5 khz at a time (which is Sony's and the standard for  shortwave slot intervals) , then
 reaching  17810 khz. from 9500khz ( initial position of band)  will take a long time  17810 - 9500 -11575
+ 10140 =  6875  then 6875 / 5 = 1375  pushes to the up-button. Which is very time consuming. Not having
a keypad to enter the desired frequency directly, Sony receiver's is only  usable from the presets. That is it will
take a significant time to tune your stations the first time, and you better do this with your car parked as it
demands a lot of  attention, but after you  put your presets in the memory , then Sony's shortwave receiver
is  roadworthy.

On the road, stepping up or down manually is impossible (distracts you from the road) .  Scanning  up or down
on shortwave (search and stop)  is very unreliable.  Sometimes  there are no strong stations  in one of the big
bands at a certain time  and the search will go forever.  Sometime  there is some cosmic noise  some place in the
wide ( now sparcely populated) spectrum  of  shortwave.  So scanning for stations is generally impractical on
shortwave.  The only way to go is through the presets!

<>In 2)  we select the band  19, 25 31 or 49 meter, then select whether 0 khz or 5khz and then manually stepping
up or down ( 10khz at a time)  in the AM band starting at 1000 khz , then we need as many as 45 pushes up
or down to find all stations in shortwave. Again with the converter it is practical to use the presets in the AM
receiver.  Search and stop station finding is somewhat better using the converter because it will seek stations
within the selected band. But it also suffers from similar problems as 1).

So the final recommendation is:  USE the PRESET's ON THE ROAD whether using a shortwave
converter or a shortwave receiver.


Removing the original OEM radio and installing an aftermarket unit with mostly different
wiring and connections can cost you as much as U$ 100 unless you can do it yourself,
besides as a rule OEM radios are better than aftermarket units.

The cost of installing a shortwave converter is generally about 1/4 of above due to the
reduced number of points to reconnect

In the case of Sony's from Asia, the rule is that Sony America doesn't carry
parts for those special models which in case they ever become defective, (although most parts
for CD players should be interchangeable) then you are
all by yourself 

In the case a converter (any brand) becomes defective, you can easily bypass it, run
your radio as before, and when the converter gets serviced then you easily connect it
back.

Often above considerations are overlooked especially the ones regarding cost of
installs. 

  Advantages
 

So, what are the advantages of  LFB digital shortwave converter when compared to other
shortwave converters ?

<>1) Digital sythesized. All internal oscillators are frequency locked so you can use the converter
    with any modern digital AM-FM  without any fine tuning
2) Being a precise and stable wideband (500 kHz) downconverter, it is digital radio ready.
    As conversion from analog to digital radio proceeds. See  digital radio  ,  the converter is
   equally capable of downconverting digital shortwave into digital AM .
    In order to use the converter with digital radio , we have to hope that the predominantly
    adopted shortwave digital radio system which seems to the DRM through out the world,
    will also be adopted by  AM  radios which seems unlikely in the short term  ( at least in the
     USA ) which seems to be biased toward the IBOC system  rather than DRM. But digital
    AM and shortwave have still a long way to go to become widespread. So buyers of shortwave
    equipment should still be concerned mainly with analog transmissions.
<>   
3) Frequency hooppable and spread spectrum ready. By changing the manually operated
    band switching remote , the converter can be transformed into the front end of a frequency
   hopping shortwave receiver.
 
 

System description

The LFB digital shortwave converter is an electronic front-end  which will allow the 4 most
important shortwave bands ( 19m, 25m, 31m and 49m ) to be listened through the AM tuner
section of a normal modern digital car sound system as used widly nowadays with no driver
intervention for long time periods.
 

Mechanical Information

.The converter fits inside an electromagnetically shielded steel box 4" x 9" x 1.125"
(102 x 226 x 28 millimeters) which is installed preferably under the dashboard for vehicles
with front antennas and preferably inside the trunk for vehicles with rear antennas. The converter is controlled through a wired remote control which installs  near the steering wheel through an adhesive support.
Weight of converter is approx. 0.6 kg. (1.3 lbs).

Information for installing

                                                          Install Info

Operation

The converter has ( ONLY ! )  2 pushbuttons for operation
.Right Button is for band selection     (each push moves to the next state as seen below)

     straight_wire => AM-FM Booster => 19m => 25m => 31m => 49m => again in
     straight_wire .............and the cycle repeats each 6 pushes.

 Left Button  selects  between shortwave stations whose frequencies are even multiples
of  5 khz ( ending in 0 khz ) and those that are odd multiples of 5 khz ( ending in 5 khz ) by toggling between the two options.

Status indication  of converter is indicated by 6 leds on the remote control as follows:

            19m band 4 red leds on (15100 to 15600 khz.)
            25m band 3 red leds on (11600 to 12100 khz.)
            31m band 2 red leds on ( 9500 to 9900 khz.)
            49m band 1 red led   on ( 5900 to 6250 khz.)
             straight_wire all leds off
             AM-FM Booster green led on

            Yellow led on indicates converter ready to tune to shortwave stations that are
                              odd multiples of 5 khz ( ending in 5 khz)
                                  like 6155, 9675, 11655 or 15445 khz
            Yellow led off indicates converter ready to tune to shortwave stations that are
                              even multiples of 5 khz (ending in 0 khz)
                                  like 6160, 9690, 11680 or 15400 khz

              This display allows for good night visibility and interpretation.
 

(Note: This converter synthesizes only multiples of 5khz. You will not be able to tune to 15107 khz for example. Either you tune to 15105 or 15110 khz. Of course 99.9% of shortwave stations transmit in frequencies that are multiples of 5 khz)
 

In-band coverage: The following frequency limits are nominal values:

                                19 meter band  ( 15100 to 15600 khz.)
                                25 meter band  ( 11600 to 12100 khz.)
                                31 meter band  (   9500 to   9900 khz.)
                                49 meter band  (   5900 to   6250 khz.)

Usually the band ranges are wider than indicated above.
For example:

        When the converter works in  the 31 meter band, it will mirror the center of the 31 meter  band (around 9700 khz.)  into approximately 1000 khz in your AM radio. So if you tune to 530 khz in your radio, you will hear what you have at 9700 - 1000 + 530 = 9230 khz.. And if you instead  tune to 1710khz, you will hear at 9700 - 1000 +1710 =10410 khz. At these extreme values, attenuation will be large due to skirt selectivity of the passband filters, but frequencies like 9400 or 10000 khz are perfectly listenable.
 

Features:There is No Fine Tuning  to make!

Once you have selected your band and whether you will hear to stations odd or even multiples
of  5 khz., then you will select a shortwave station with the same convenience as selecting an AM
station on your digital AM section of your car stereo !

                   Included AM-FM Booster
The AM-FM Booster is a 10 db gain AM (6 db FM gain) amplifier usable mainly in areas where only weak signals exist. Due to the fact that these are broadband amplifiers, their use is not recommended in regions where powerful AM FM stations exist, as they are subject to overloading.
It is included for added convenience to some users.

                   Triple conversion ?
The converter acts as a double conversion front end, and with the conversion you have inside your AM radio it will make a triple conversion SW receiver.

                   Ease of operation
while driving either day or night was of prime concern in this design.

World Geographical usage:
(Warning: This design makes use of car digital AM radios used in the Americas ( Western Hemisphere ) from Alaska U.S.A. to Tierra del Fuego Argentina where adjacent channels are 10 khz apart by convention.
     If you live in Europe, Asia Africa or Australia where adjacent channels are 9 khz apart, it is recommended that you use a switchable 9 khz/10 khz aftermarket AM/FM Car Radio which are
plentiful these days. Use of a 9 khz AM radio with our converter will lead to:
          22.222 % of shortwave stations will be properly tuned
          44.444 % of shortwave stations will be off tune by 1 khz....almost unperceptible
    and 33.333 % of shortwave stations will be off tune by 2 khz.... listenable but.... somewhat
degraded ... and not too nice to your ears! )

More on usage if you live in
Europe, Asia, Africa, Australia, Etc

> I did study your webpage but I'm not qualified to understand the

> implications of the 9 or 10 kHz issue. That is, when I press the "fast"

Hi Magnus,

I will attempt to explain the problem,

Let us take the stations I listen most, these are

BBC at 15400

converter transforms to 1090 kHz (if yellow OFF) or 1085 kHz (yellow ON)

BBC at 12095

converter transforms to 1305 kHz (if yellow OFF) or 1300 kHz (yellow ON)

BBC in portuguse at 15390

converter transforms to 1080 kHz (if yellow OFF) or 1075 kHz (yellow ON)

As I have a 10 kHz step radio then my radio will tune to.....

......1060, 1070, 1080, 1090 ,1100, 1110,....1290, 1300, 1310, 1320 etc.etc.
 

so with the proper choice of yellow ON or OFF I can match 1080, 1090 ,1300.
 

but with a 9 kHz radio then

1062, 1071, 1080, 1089, 1098, 1107, 1116......1287, 1296, 1305, 1314 etc.
 

Now BBC at 15400 will show at 1090 or 1085. Here the best match is 1089

so the difference will be 1 kHz . Here you will be all right but not perfect.

Now BBC at 12095 will show at 1305 or 1300 . Here you are lucky 1305

will tune perfectly.

Now BBC at 15390 will show at 1080 or 1075. Here again you are very

lucky 1080 will tune perfectly.
 

But suppose your image was at 1060 or 1055. Then you have 1053 or 1062 to

choose from in your 9 kHz tuner. You will be 2 kHz off either way ,

this is not that good. typical ceramic filters in AM radios + - 3 kHz.

So the conclusion is: you can use the converter with a 9kHz steps but

some stations will be degraded.
 

Hope this explains your doubt.

Write me again if you don't understand.

Regards

LFB

How to find your sw station ?
In order to find your favorite shortwave station in your AM radio look at the table below for conversion offsets:
 

   Band       19 m        25 m        31 m          49 m
Yellow LED OFF     14310      10790         8710         5030
Yellow LED 
ON
    14305      10795        8715         5025

Suppose you like to hear the BBC at 12095 khz. In this case it is an odd multiple of 5 khz so you select 25 meter band with Yellow LED ON. So it is as simple as 12095 - 10795 = 1300 khz and this is the frequency you will find the BBC  in your AM radio .

Software downloads

Download igni1.asm
Download igni1.hex , 5ms.dwell, extra sparks included
Download mpasm.exe          Changed .exe for .exu
Download p16F84.inc           Changed .inc for .inz
Download ate.bat   batch file          Changed .bat for .but

Angelfire protects you by not allowing you to download .exe or .bat or .inc files
So I have renamed them for uploading and you will rename them at downloading
 
                                                  Return to Bosch digital ignition

Design features
The converter is built around 2 NE602 mixers , has CMOS logic for low synthesizer noise, has a
wideband high-impedance front-end, has all-electronic switching between bands (only 2 tact switches(buttons) for complete operation) and is build on high quality epoxy-fiberglass PC boards.

Ordering Information
Price is U$140 plus about U$28 for air postage to the western hemisphere and U$ 33 for Europe.The converter carries with it a 2-year warranty including parts and labor assuming that the converter was not abused, and not tampered-with.Warranty does not include postage in either direction.
Money back guarantee. Test converter for 45 days. If it is not up to your expectation you can ask for a refund. Subject to the same terms as the 2 year warranty. Should you have any further question please feel free to ask.

LFB Ind. & Com. Ltda.     Phonefax 55 11 3115 0397   e-mail: swlfb@vivointernetdiscada.com.br
 

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