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My comments at bottom.

--- In BITX20@..., Rahul Srivastava <vu3wjm@y...> wrote:

Hi!

Some one once mentioned , thumbrule for xtal matching was within 10%

of the required BW. However I try to keep it within 100hz for SSB filters.

Till date all appear to have worked fine.

73

Rahul VU3WJM

PS: I make the BFO first and with 33pf in series with xtal measure

all available with me. Select ones within 100hz of each other . Take
the lowest one for carrier osc for BITX , takes care of xtal pulling.

This is a good thing to do. Having done lower sideband by picking
a high crystal makes pulling it high easier.

One other trick. Using the BFO to pick the crystals is a good first
step. Once the filter is fabricated you can use the BFO to sweep the
filter to assess the filter shape and bandwidth. Usually that
requires tacking on a coil and larger tuning capacitor temporarily.


Allison
KB1GMX

Hi,

I never saw anything about the original article about this.? I've used
the BFO and a frequency counter to measure all my crystals.? How
closely do they need to be matched for SSB reception?? for CW reception?

Thanks,

The Eternal Squire

P.S.? I am using 10.7 Mhz as the IF

---

NEW - crystal clear PC to PC

Hello,

Experience and also literature suggests less than 100hz for SSB
bandwidth (2.2-2.8khz) and less than 1/10th the bandwidth
or >30hz for CW filters (200hz to 800hz bandwidth).

Practical filters also depend on crystal Q and series resistance
among other factors for sucess.

My experience with many published recipie design filters is if they
are just built with any crystal they will likely work but bandwidth
and passband shape will be unpredictable. Usually the passband shape
is degraded the worst. So simply matching for frequency is only one step.

Allison
KB1GMX
--- In BITX20@..., "eternalesquire" <eternalsquire@c...>
wrote:

Hi,

I never saw anything about the original article about this. I've used
the BFO and a frequency counter to measure all my crystals. How
closely do they need to be matched for SSB reception? for CW reception?

Thanks,

The Eternal Squire

P.S. I am using 10.7 Mhz as the IF

Hi,

Have a look at messages 124 and 131.

I found a set of 4 crystals within 30 Hz and they are doing fine for
SSB. I have posted a plot of the resulting filter passband in the
files section. Look for BITX20_10MHz_crystalfiler_2.sxc.pdf

73 Heinz, OE5EEP

--- In BITX20@..., "eternalesquire" <eternalsquire@c...>
wrote:

Hi,

I never saw anything about the original article about this. I've used
the BFO and a frequency counter to measure all my crystals. How
closely do they need to be matched for SSB reception? for CW reception?
P.S. I am using 10.7 Mhz as the IF

Hi,

I never saw anything about the original article about this. I've used
the BFO and a frequency counter to measure all my crystals. How
closely do they need to be matched for SSB reception? for CW reception?

Thanks,

The Eternal Squire

P.S. I am using 10.7 Mhz as the IF

Hello,

This email message is a notification to let you know that
a file has been uploaded to the Files area of the BITX20
group.

File : /BITX 15 + PLL/MULTIBAND_BITX_B1.PDF
Uploaded by : eb7hpm <msraya@...>
Description : Multiband Design for BITX FI TX/RX

You can access this file at the URL:


To learn more about file sharing for your group, please visit:


Regards,

eb7hpm <msraya@...>

Hello,
I just dropped the schema how I measured the curves of the ladderfilter
in the Files box, folder: "Ladder Crystal Filter Design". One is in
GIF the other one is in SPL. The last one can be viewed and printed
with: SPLANViewer50.exe, also in the Files box, folder "PE2BS".

73
Ruud
PE2BS

Hi Chris,

Thanks for your comment. When the filter is part of the new BITX80/20
I will have to match the filter in the trcvr again. With you I wonder
how it will be, special because the filter is used in two directions.
I will drop the pictures by that time in the group.

73

Ruud.
PE2BS

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

Very nice shape, nice experiment too.
Like to mentioned, matching is important. I wonder how the shape

looks

when it is part of the BITX but I am sure you will add it.
Chris.

--- In BITX20@..., "Ruud Jongeling" <pe2bs@t...> wrote:

Hi fellow BITX-ers,

About one or two months ago I promised to report of my ladder

filter

experiment on 9MHz. I just dropped the files with shape-pictures

in

the

Files box. See the folder "Ladder Crystal Filter Design".
There is also an Excel file that can be used for your own

experiments.

To give you a short summary: it can be done but without measuring

the

shape it is a bit of lotery, like Max said in earlier messages.

73

Ruud
PE2BS

Very nice shape, nice experiment too.
Like to mentioned, matching is important. I wonder how the shape looks
when it is part of the BITX but I am sure you will add it.
Chris.

--- In BITX20@..., "Ruud Jongeling" <pe2bs@t...> wrote:

Hi fellow BITX-ers,

About one or two months ago I promised to report of my ladder filter
experiment on 9MHz. I just dropped the files with shape-pictures in

the

Files box. See the folder "Ladder Crystal Filter Design".
There is also an Excel file that can be used for your own

experiments.

To give you a short summary: it can be done but without measuring

the

shape it is a bit of lotery, like Max said in earlier messages.

73

Ruud
PE2BS

Hi fellow BITX-ers,

About one or two months ago I promised to report of my ladder filter
experiment on 9MHz. I just dropped the files with shape-pictures in the
Files box. See the folder "Ladder Crystal Filter Design".
There is also an Excel file that can be used for your own experiments.

To give you a short summary: it can be done but without measuring the
shape it is a bit of lotery, like Max said in earlier messages.

73

Ruud
PE2BS

Hello,

This email message is a notification to let you know that
a file has been uploaded to the Files area of the BITX20
group.

File : /Ladder Crystal Filter Design /X-tal 9 MHz.xls
Uploaded by : pe2bs <pe2bs@...>
Description : Excel file to 9MHz filter experiment

You can access this file at the URL:


To learn more about file sharing for your group, please visit:


Regards,

pe2bs <pe2bs@...>

Hello,

This email message is a notification to let you know that
a file has been uploaded to the Files area of the BITX20
group.

File : /EGR/BITX_rev_B.zip
Uploaded by : eternalesquire <eternalsquire@...>
Description : BITX Engineer Diagrams, Rev B

You can access this file at the URL:


To learn more about file sharing for your group, please visit:


Regards,

eternalesquire <eternalsquire@...>

Rob,

I just compared the emitter circuits with the originals. Yup, you
called it. I will fix this and put this out in Rev B asap.

The Eternal Squire

Hi Arv & Ron,

It appears that the bidirectional amplifiers cannot be biased correctly, with those 100 nf in series with the emitters. I haven't looked, but I suspect they are in parallel with the emitter resistors instead of series as you have them.

73,

Rob
On Aug 14, 2005, at 7:27 AM, Ron McDowell - W5RCM / ZS1MCD wrote:

I don't get credit for that... eternalsquire did the work...I just converted his BMPs to GIFs.
--
72, Ron - W5RCM / ZS1MCD
Austin TX / Hermanus ZA


On 14 Aug 2005 08:24:46 -0600, [Arv Evans <arvevans@...>] wrote:
Ron W5RCM

Very good job on the schematics. This should also help a lot for those who
want to do their BITX as modules.

Thanks,

Arv K7HKL

On Sunday 14 August 2005 08:05 am, Ron McDowell - W5RCM / ZS1MCD wrote:

Very nice job, Eternal Squire!

I have converted these to GIF format... you can grab them all from
--
72, Ron - W5RCM / ZS1MCD
Austin TX / Hermanus ZA


On 14 Aug 2005 08:09:23 -0000, [eternalesquire
<eternalsquire@...>] wrote: All,

I'm starting to need reading spectacles, so I took the liberty of
redrafting the schematic submitted by Mr. Farhan into a series of
modular documents that should take somewhat less effort to view finer
details such as decimal points. I tried as hard as I could to make
them reflect best engineering practices as I currently understand them.

I've incorporated what appear to be the most popular modifications
I've seen in this group to date that also keep to the spirit of
requireing only those parts reasonably obtainable in India to an
amateur of limited finances. I've also imade annotations derived
from Mr. Farhan's text where appropriate for clarity.

The source documents were drawn using the latest version of LTSpice,
available from the Linear Technology website. I then exported them
into Word bitmap files. Finally, I retouched those files to add
details not available from LTSpice, such as variable capacitors.

Please note that the LTSpice diagrams themselves are not runnable, I
merely used the tool as a drafting aid.

Please feel free to make corrections as appropriate. One thing I
would recommend is other sets of capacitor values for different IF
frequencies. I hope others will add to Table 1 in TRANSCEIVER.bmp,
more working choices for IF's besides 9 and 10 Mhz.

You'll find this archive uploaded into as EGR&#92;BITX.zip

Enjoy,

The Eternal Squire



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--
Rob Frohne, Ph.D., P.E.
E.F. Cross School of Engineering
Walla Walla College

Hi,

Another piece of useful advice re VFO tuning. I have found that
coupling the VFO capacitor to the load side of a plastic planetary
gear drive kit (used in toy boats and aircraft) provides a very
compact means of extremely stable tuning without backlash. The tuning
knob should be coupled to the motor side of the gear drive to acheive
the gear reduction.

These are offered in the US in HobbyTown stores for about USD 12.
These are usually imported from Japan.

The Eternal Squire

Hi,

All the graphic formats are supported here, those are no
problem. I specifically do not run the "MS Office Suite"
as they are klunky and slow never minding a security issue.

Got the files and they are very good work.

Allison
KB1GMX
--- In BITX20@..., "eternalesquire" <eternalsquire@c...>
wrote:

Hi,

I'm sending my response as a group letter. I just recently uploaded a
new .ZIP with the A revision of the engineering diagrams, as
EGR&#92;BITX_rev_A

Allison, I meant to say that the format is .BMP, which should be
readable by open source tools. Sorry, I was very tired last night
when I wrote the letter.

Ron, do you think that it might make more sense to insert .GIF and
other formats for these same files in the archive, and then repost as
a new zip under the EGR directory? That way there would be one
centralized location.

Rahul, I truly appreciate the extra set of eyes! I believe I have
made the fixes you pointed out. I also spotted a few cosmetic
problems as well.

Everyone else, could you all please compute crystal filter capacitors
CXA and CXB for the IF frequencies 3579, 8000, 10245, and 10700 kHz,
or other favorites? I especially need 10700 kHz, as I have a huge
bunch of them here, and they are a standard IF frequency anyways.

Thank you all for the compliments, I hope I can be of further service
to the group.

The Eternal Squire

Hello,

This email message is a notification to let you know that
a file has been uploaded to the Files area of the BITX20
group.

File : /KB1GMX/PIN-ATT1.jpg
Uploaded by : ajparent1 <kb1gmx@...>
Description : PIN diode PI attenuator jpg

You can access this file at the URL:


To learn more about file sharing for your group, please visit:


Regards,

ajparent1 <kb1gmx@...>

I have put the revised gifs out at for those who want them.

Squire, I've got no problem if you want to roll these up into your zip file. Go for it!
--
72, Ron - W5RCM / ZS1MCD
Austin TX / Hermanus ZA

Hi,

I'm sending my response as a group letter. I just recently uploaded a
new .ZIP with the A revision of the engineering diagrams, as
EGR&#92;BITX_rev_A

Allison, I meant to say that the format is .BMP, which should be
readable by open source tools. Sorry, I was very tired last night
when I wrote the letter.

Ron, do you think that it might make more sense to insert .GIF and
other formats for these same files in the archive, and then repost as
a new zip under the EGR directory? That way there would be one
centralized location.

Rahul, I truly appreciate the extra set of eyes! I believe I have
made the fixes you pointed out. I also spotted a few cosmetic
problems as well.

Everyone else, could you all please compute crystal filter capacitors
CXA and CXB for the IF frequencies 3579, 8000, 10245, and 10700 kHz,
or other favorites? I especially need 10700 kHz, as I have a huge
bunch of them here, and they are a standard IF frequency anyways.

Thank you all for the compliments, I hope I can be of further service
to the group.

The Eternal Squire

Hello,

This email message is a notification to let you know that
a file has been uploaded to the Files area of the BITX20
group.

File : /EGR/BITX_rev_A.zip
Uploaded by : eternalesquire <eternalsquire@...>
Description : BITX Engineering Drawings, Revision A, 14 AUG 2005

You can access this file at the URL:


To learn more about file sharing for your group, please visit:


Regards,

eternalesquire <eternalsquire@...>