开云体育

That is a good starting point but I'd add much has been published
since then on building crystal filters.

Using the series ladder design and the right constants you can build
USB and LSB filters as well as symetrical. A good source is the ARRL
publication Experimental Methods in RF Design which devotes a fair
amount of text to crystal filters and has a good listing of citings
for further reference.

I've use their techniques to build excellent filters using 6 and 8
crystals with symetrical shapes to greater than 70db and low ripple.
The gausian to 6db shape happens to sound the best to me for 2.2khz
SSB filters. I'm using a 6 crystal version of same in the first
version of BITx I've built as an transverter IF.

Allison
KB1GMX

de 4N1ZM

There is two programs and alternative aproach to ladder filter design.
Since altavista translation can overcame language bariers it is
possible to check this link through systran translation engine.
Program give obvious relation between impedance capacitance and
crystal unit mesurmen tools:

de 4N1ZM

I added older easier for understanding version of ladder filter
desingn program in file section under 4N1ZM folder.

--- In BITX20@..., "Max" <m_orwell@y...> wrote:

de 4N1ZM

There is two programs and alternative aproach to ladder filter

design.

Since altavista translation can overcame language bariers it is
possible to check this link through systran translation engine.
Program give obvious relation between impedance capacitance and
crystal unit mesurmen tools:




--- In BITX20@..., "ajparent1" <kb1gmx@a...> wrote:

That is a good starting point but I'd add much has been published
since then on building crystal filters.

Using the series ladder design and the right constants you can

build

USB and LSB filters as well as symetrical. A good source is the

ARRL

publication Experimental Methods in RF Design which devotes a

fair

amount of text to crystal filters and has a good listing of

citings

for further reference.

I've use their techniques to build excellent filters using 6 and

8

crystals with symetrical shapes to greater than 70db and low

ripple.

The gausian to 6db shape happens to sound the best to me for

2.2khz

SSB filters. I'm using a 6 crystal version of same in the first
version of BITx I've built as an transverter IF.

Allison
KB1GMX

Hi Paul and Max,

Thanks for your info about the design of a ladderfilter. The
ladderfilter was subject in this group before. Building the BITX20 I
made a shape of the ladderfilter with the program SpectrumAnalyzer
(see also msg 460: "Shape of Ladderfilter easy to measure" by Chris
v.d. Berg). I noticed some differences between the theory and the
actual shape of the filter, see the pictures in the Photo-box and the
messages about them.

From Chris I received an article from G3JIR in QST nov. 80 about
Ladder Filter Design. A copy is dropped in the Files-box. The filters
discribed looks like the filters in the Russian program Max put in
the File-box. I am working on a 9MHz filter following the steps G3JIR
discribed. With the SpectrumAnalyzer it is not difficult to measure
the bandwith of the filters and Excel can calculate the impedance of
the filters and the C's in the filters.

Doing the measurements I noticed that matching the impedance is very
important for the filtershape. Changing the C's makes great impedance
changes. (33 pF, R= 328 Ohm, C=76 pF, R= 142 Ohm on the 2nd order
test filter) That's why I asked some information about matching the
impedance in the amplifierstages in the BITX20 (msg 868). I am still
waiting for a reply....

When I completed the design of the filter I will drop the info in the
Files-box and the shape pictures Photo-box. I hope you will drop
pictures of your filtershapes too.

73

Ruud.






--- In BITX20@..., "Max" <m_orwell@y...> wrote:

de 4N1ZM

I added older easier for understanding version of ladder filter
desingn program in file section under 4N1ZM folder.

--- In BITX20@..., "Max" <m_orwell@y...> wrote:

de 4N1ZM

There is two programs and alternative aproach to ladder filter

design.

Since altavista translation can overcame language bariers it is
possible to check this link through systran translation engine.
Program give obvious relation between impedance capacitance and
crystal unit mesurmen tools:




--- In BITX20@..., "ajparent1" <kb1gmx@a...> wrote:

That is a good starting point but I'd add much has been

published

since then on building crystal filters.

Using the series ladder design and the right constants you can

build

USB and LSB filters as well as symetrical. A good source is

the

ARRL

publication Experimental Methods in RF Design which devotes a

fair

amount of text to crystal filters and has a good listing of

citings

for further reference.

I've use their techniques to build excellent filters using 6

and

8

crystals with symetrical shapes to greater than 70db and low

ripple.

The gausian to 6db shape happens to sound the best to me for

2.2khz

SSB filters. I'm using a 6 crystal version of same in the

first

version of BITx I've built as an transverter IF.

Allison
KB1GMX

Within the base ladder filter topology there are subgoups of type.
They can designed as minimum loss, butterworth, linear phase or
Chebychev not unlike LC filters. Each has it's differences and
sailent characteristics. When designing any of these filter the
meaurement of the crystals used is important for the result to be
close to the design prediction. Measurement includes frequency,
motional L, motional C, holder C and Q. All interact. Using 4
crystals of the same type and frequency does not assure the builder
the expected result though usually it will be close. Once the
crystals are known and a design selected the termination impedence
will also be a factor. That is one design criteria, the filters
sensitivity to termination.

When I select crystals from a group of the same lot I often find
besides frequency variation some units that have significantly
different Q [usually inferior] to the rest of the lot. The
variations can be as great as 3:1. An inferior crystal such as
that will be acceptable in an oscillator but would degrade a filter
if used in one.

While this is not meant to be exhaustive by any means. It helps
explain why theory and result will be dissimilar.


Allison
KB1GMX

Hi Ruud,
as I remember, you asked for a solution in the circuit, by using other
resistors.
I kept the circuit 'original' and added very small transformers,
pictures can be seen in the BITX17 Photos directory.
I did many experiments with several values of components, did many
measurements (by soundcard) so the differences can be seen easily (as
you know, but other may not).
Best regards,
Chris.

Doing the measurements I noticed that matching the impedance is very
important for the filtershape. Changing the C's makes great

impedance

changes. (33 pF, R= 328 Ohm, C=76 pF, R= 142 Ohm on the 2nd order
test filter) That's why I asked some information about matching the
impedance in the amplifierstages in the BITX20 (msg 868). I am still
waiting for a reply....

de 4N1ZM

I was looking in different designs of ssb trx and it looks like that
most important part is exactly filter. And that is place where
successful work of trx can easy fail. Crystals are simply different
from producer to producer from lot to lot. Without measuring to get
good filter is more lottery than predictable result. Only in
situation that somebody can use the same type of crystals producer
and batch results might be comparable.

One other approach is Kohn type filter with all same capacitance
values that can be trimmed by variable c or varicaps in the section.
That one looks most permissible and easy try without much work.

Here is link to collection of all ladder filter approaches:



You should fist get djvu viewer from

By the way djvu format is the most efficient for schematics size on
the net, even in comparison to pdf.




--- In BITX20@..., "Max" <m_orwell@y...> wrote:

de 4N1ZM

There is two programs and alternative aproach to ladder filter

design.

Since altavista translation can overcame language bariers it is
possible to check this link through systran translation engine.
Program give obvious relation between impedance capacitance and
crystal unit mesurmen tools:




--- In BITX20@..., "ajparent1" <kb1gmx@a...> wrote:

That is a good starting point but I'd add much has been published
since then on building crystal filters.

Using the series ladder design and the right constants you can

build

USB and LSB filters as well as symetrical. A good source is the

ARRL

publication Experimental Methods in RF Design which devotes a

fair

amount of text to crystal filters and has a good listing of

citings

for further reference.

I've use their techniques to build excellent filters using 6 and

8

crystals with symetrical shapes to greater than 70db and low

ripple.

The gausian to 6db shape happens to sound the best to me for

2.2khz

SSB filters. I'm using a 6 crystal version of same in the first
version of BITx I've built as an transverter IF.

Allison
KB1GMX

Indeed measuring is knowing if the final result is in line with the
original expectations.
As mentioned before, it can be easily done with the sound card. At that
time, I asked for feedback (screenshots of the same method) of measured
filters to see if my 4,9 MHz filter is about in line with the 10 MHz
version. If some members do this measurement it is possible to compare
results and find out if it is really a 'lottery'. As I understand, most
builders have their filter dimensioned in accordance with the original
schematic and they all seems to work fine?
OK builders, please download the few kb program, connect your BITX to
the sound card, measure the shape of the filter and post the screendump!
Thanks in advance,
Chris.

Hi Chris,

Thanks for your answer. As you can see in my reply to Allison I will
follow your advices.

With you I hope that more pictures of the filtershape will be
dropped it in this group. The arguments Max gave in his reply makes
more clear to me that a filter design have to be checked by measuring
the result.

On the moment I am still working on the 9MHz filter The first part of
the design (2nd order test filter and calculating new C's and
impedance) worked well. In 4 steps I came to desired bandwith, all
pictures are saved so the process can be followed.
Now I have two things to do:
1. Match te impedance of the filter to the amplifierstages.
2. See how the calculated C's does work out on a 4th order filter.
When there are results I will drop them in this group.

In "RF Amplifier Classics", 1-10 there is a design with two IRF510 in
push-pull on 28 V giving over 40W with 1 W drive. Mail me if you want
a copy of the article.

73

Ruud (PE2BS)





--- In BITX20@..., "vdberghak" <vdberghak@z...> wrote:

Hi Ruud,
as I remember, you asked for a solution in the circuit, by using

other

resistors.
I kept the circuit 'original' and added very small transformers,
pictures can be seen in the BITX17 Photos directory.
I did many experiments with several values of components, did many
measurements (by soundcard) so the differences can be seen easily

(as

you know, but other may not).
Best regards,
Chris.

Doing the measurements I noticed that matching the impedance is

very

important for the filtershape. Changing the C's makes great

impedance

changes. (33 pF, R= 328 Ohm, C=76 pF, R= 142 Ohm on the 2nd order
test filter) That's why I asked some information about matching

the

impedance in the amplifierstages in the BITX20 (msg 868). I am

still

waiting for a reply....

With the software and connecting the output of the AF amp to PC, i wonder where do we set the BFO to find out the shape of our filter, assuming that we do not know the center frequency yet, or setting the BFO is not necessary?

rgds
julius

* REPLY SEPARATOR *

On 7/20/2005 at 9:14 AM vdberghak wrote:

Indeed measuring is knowing if the final result is in line with the
original expectations.
As mentioned before, it can be easily done with the sound card. At that
time, I asked for feedback (screenshots of the same method) of measured
filters to see if my 4,9 MHz filter is about in line with the 10 MHz
version. If some members do this measurement it is possible to compare
results and find out if it is really a 'lottery'. As I understand, most
builders have their filter dimensioned in accordance with the original
schematic and they all seems to work fine?
OK builders, please download the few kb program, connect your BITX to
the sound card, measure the shape of the filter and post the screendump!
Thanks in advance,
Chris.

Without measuring to get
good filter is more lottery than predictable result. Only in
situation that somebody can use the same type of crystals producer
and batch results might be comparable.

Yahoo! Groups Links

___________________________________________________________
Gesendet von Yahoo! Mail - Jetzt mit 1GB Speicher kostenlos - Hier anmelden:

In German Funkamateur was published schematic for hf noise generator
and described metod of mesurment by using sondcard lf spectogram. I
am sorry that it is again in russian but can be easily translated. I
couldnt find similar article in english. Schematics are
understandable on its own.




--- In BITX20@..., "vdberghak" <vdberghak@z...> wrote:

Indeed measuring is knowing if the final result is in line with

the

original expectations.
As mentioned before, it can be easily done with the sound card. At

that

time, I asked for feedback (screenshots of the same method) of

measured

filters to see if my 4,9 MHz filter is about in line with the 10

MHz

version. If some members do this measurement it is possible to

compare

results and find out if it is really a 'lottery'. As I understand,

most

builders have their filter dimensioned in accordance with the

original

schematic and they all seems to work fine?
OK builders, please download the few kb program, connect your BITX

to

the sound card, measure the shape of the filter and post the

screendump!

Thanks in advance,
Chris.

Without measuring to get
good filter is more lottery than predictable result. Only in
situation that somebody can use the same type of crystals

producer

and batch results might be comparable.

Excellent page here not only provides the uncrippled Spectrogram for download but a noise generator and many other goodies as well.

73

Rahul VU3WJM

?

?

With the software and connecting the output of the AF amp to? PC, i wonder where do we set the BFO to find out the shape of our filter, assuming that we do not know the center frequency yet, or setting the BFO is not necessary?

rgds
julius

* REPLY SEPARATOR? *

On 7/20/2005 at 9:14 AM vdberghak wrote:

>Indeed measuring is knowing if the final result is in line with the
>original expectations.
>As mentioned before, it can be easily done with the sound card. At that
>time, I asked for feedback (screenshots of the same method) of measured
>filters to see if my 4,9 MHz filter is about in line with the 10 MHz
>version. If some members do this measurement it is possible to compare
>results and find out if it is really a 'lottery'. As I understand, most
>builders have their filter dimensioned in accordance with the original
>schematic and they all seems to work fine?
>OK builders, please download the few kb program, connect your BITX to
>the sound card, measure the shape of the filter and post the screendump!
>Thanks in advance,
>Chris.
>
>> Without measuring to get
>> good filter is more lottery than predictable result. Only in
>> situation that somebody can use the same type of crystals producer
>> and batch results might be comparable.
>
>
>
>
>
>
>
>Yahoo! Groups Links
>
>
>




?????

?????
????? ?????
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Gesendet von Yahoo! Mail - Jetzt mit 1GB Speicher kostenlos - Hier anmelden:

---

NEW - crystal clear PC to PC

Hi Julius,
that is the fun, nothing to adjust in advance, just connect it (I
used two resistors as a signal attunuator)and watch the screen (if
you receive enough noise).
If you do not receive enough noise, you can choose that the peak is
hold, slowly tune over a carrier (can be anything, no requirements
about stability or so)and see the graph.
In fact, using this tool makes it easy to see if the BFO frequency
is correct. If you just click the link in 'Links, software' or click
on you can see many samples
and an easy explenation.
(If you do not want to connect it and first want to see how it
works, you can use your microphone and hold it in front of the
speaker).
Please keep us informed about the results.
Thanks in advance,
Chris.

--- In BITX20@..., "Wijaya, J." <iyung_w@y...> wrote:

With the software and connecting the output of the AF amp to PC,

i wonder where do we set the BFO to find out the shape of our
filter, assuming that we do not know the center frequency yet, or
setting the BFO is not necessary?

rgds
julius

Hello friends

I am building another BITX40, my other with two bands work great but
there are many external boxes to plug togheter...

If you are looking articles for mesurenents of filtres by sound card
in english try :



I have the Spectra and the Gram softwares, bouth work very nice...
For good results build the filter and the input IF amplifier / output
IF amplifier, BFO, 2nd mixer (demodulator) and the audio amplifier...
Remember that if you change the impedance of input or output of the
filter you change the filter caracteristics. A good idea is to adjust
using the real circuit.

I am building my filter using Fahran way... I buy 20 10MHz xtal ... I
make a oscilator circuit and measure the frequency with and withot a
33pF ... now I am assembling others parts...for to analize the
filter...

If you want to build a Noise Generator ... it is easy ... make a RF
amplifier with two estages ending with a broad band bifilar
transformer, in the input you need to test some Zener diodes types
(more power and low voltage give best results) ... gud luck

I will upload two versions of the freeware GRAM spectroanalizer ...


73 from Brazil

PY2OHH Miguel


--- In BITX20@..., "Max" <m_orwell@y...> wrote:

In German Funkamateur was published schematic for hf noise

generator

and described metod of mesurment by using sondcard lf spectogram. I
am sorry that it is again in russian but can be easily translated.

I

couldnt find similar article in english. Schematics are
understandable on its own.




--- In BITX20@..., "vdberghak" <vdberghak@z...> wrote:

Indeed measuring is knowing if the final result is in line with

the

original expectations.
As mentioned before, it can be easily done with the sound card.

At

that

time, I asked for feedback (screenshots of the same method) of

measured

filters to see if my 4,9 MHz filter is about in line with the 10

MHz

version. If some members do this measurement it is possible to

compare

results and find out if it is really a 'lottery'. As I

understand,

most

builders have their filter dimensioned in accordance with the

original

schematic and they all seems to work fine?
OK builders, please download the few kb program, connect your

BITX

to

the sound card, measure the shape of the filter and post the

screendump!

Thanks in advance,
Chris.

Without measuring to get
good filter is more lottery than predictable result. Only in
situation that somebody can use the same type of crystals

producer

and batch results might be comparable.

Hi Chris and Julius,

In the experiments with 9MHz filter the crystals turned out to be
about 9.015MHz. With the BFO exactly on 9.005 MHz I get both sides of
the filter and I can determine the centerfrequency of the filter. I
put a picture in the Photo-box (PE2BS). The red one is without
matching impedance, the green one after matching. The filter is not
ready so it's just an exemple of the use of SpectrumAnalyzer.
73

Ruud (PE2BS)

--- In BITX20@..., "vdberghak" <vdberghak@z...> wrote:

Hi Julius,
that is the fun, nothing to adjust in advance, just connect it (I
used two resistors as a signal attunuator)and watch the screen (if
you receive enough noise).
If you do not receive enough noise, you can choose that the peak is
hold, slowly tune over a carrier (can be anything, no requirements
about stability or so)and see the graph.
In fact, using this tool makes it easy to see if the BFO frequency
is correct. If you just click the link in 'Links, software' or

click

on you can see many samples
and an easy explenation.
(If you do not want to connect it and first want to see how it
works, you can use your microphone and hold it in front of the
speaker).
Please keep us informed about the results.
Thanks in advance,
Chris.

--- In BITX20@..., "Wijaya, J." <iyung_w@y...> wrote:

With the software and connecting the output of the AF amp to PC,

i wonder where do we set the BFO to find out the shape of our
filter, assuming that we do not know the center frequency yet, or
setting the BFO is not necessary?

rgds
julius