--- In BITX20@..., Jim Strohm <jstrohm@e...> wrote:

On Jul 10, 2005, at 7:04 AM, Ashhar Farhan wrote:

while PLL chips are difficult to find, the 16F84 or the 16F628 are
plentiful. why can't we program the PIC to behave as a PLL on it's
own?

the PIC timer can be used to accurately measure the oscillator
frequency
(as normal PIC based frequency counters do) instead of displaying the
frequency on a display, it can (in addition) also pump a capacitor
that
in turn is used to bias a varactor across the VFO.

if chris and his merry band can do a single chip HnP, there is no
need to
assume that they can't turn out a single mirochip PLL too.

Given how cheap a PIC is, I think it's just a matter of time before
we stop using standard TTL/CMOS logic, and start programming PICs as
replacements. They won't be pin-for-pin replacements, but they'll be
easier to locate than some of the more esoteric logic chips.

A PIC PLL sounds like a fabulous project.

Jim N6OTQ

Three things:

PIC is a sequential device, there are whole classes of logic solutions
that are not easily done with a sequential device.

Using the PIC as a PLL, it could be done but even the fastest parts
are far too slow to be succiciently precise. With PLLs a lack of
precision can be causes noise in the signal. The core of most PLLs
is the phase detector which is usually a very fast sequential logic
element to in real time compare the phse of two signals. Hard to do
well enough with a PIC.

Using a PIC for HnP and display, this is very do able.

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

Yes Paolo,
I'm a memeber of this list and just for this reason I discovered this good
RTX and decided to show to other italian Hams... hi!

Best 73

Alex I0SKK




-----Messaggio originale-----
Da: BITX20@... [mailto:BITX20@...] Per conto di
Paolo Cravero as2594
Inviato: venerdì 8 luglio 2005 9.05
A: BITX20@...
Oggetto: [BITX20] Article about BITX20 on Italian magazine

Hi,
I just discovered that a series of 4 articles about BITX20 has been
published on the Italian magazine "RadioKit Elettronica" (03/2005 to
06/2005):






Unfortunately I am not a reader of this magazine, so I totally missed
the article and can't comment.

I wonder: is the author subscribed to this list?!?!?!?

73,
Paolo IK1ZYW

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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

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:

Dear Friends

I wish to let you know that VUQRP will be making "PCB Making kit"
available to VU hams who are interested in homebrewing.

The price of the kits will be around Rs.325/- plus postage or courier
charges. Very soon we will be uploading the pictures of the kits on
our vuqrp group site.

Please do get in touch with us if you are interested in getting these
kits. drop us mail at vu3bgi@...

73's

de vu3bgi

开云体育

How about a PIC based Huff & Puff stabilized VFO that could also display the
frequency?

Arv K7HKL
_._

--- In BITX20@..., "Ron" <pa2rf@y...> wrote:

Hi fellow BITX-homebrewer,
Yesterday I was browsing through some old "Electrons" (Dutch Ham
magazine) and found an interesting article in which it was told that
our famous MOSFET IRF-family (in particular IRF510 and IRF540) could
work on 50 MHz ! I am surprised by this. The article did not show
fixed designs, so maybe it is just wishfull thinking...
According to the article, achievable power levels should less lower
than at, let's say 7 MHz ( 2 Watts versus 12 Watts RF).
Anybody experience in this field ?

To drive the input of the mosfet at 6M you will have to use very
different networks so the input capacitance can be absorbed into the
network. Same would have to be done for output. Major redesign
of the "linear module" is the result. I've tried the IRF510 and
friends and they can generate fair power at 6m but they are hard to
drive and not as stable. Devices like the 2SC1307, 2sc799, 2sc1970
and 2sc1971 are easier to use and fairly common (found in 27,mhz
US CB radios). Power out with those can be as high as 10W.

However, with an IF of 10MHz, VFO freq of 40MHz might be too high to
get a (simple) rock-stable VFO.

The easiest way to get a 40mhz VFO is to take a 4mhz VFO and mix it
with a 36mhz crystal and filter the result to 40mhz. then you get the
stability of 4mhz VFO and the required high frequency.

I'm doing it with whats called a sampling tracking PLL. Simpler
than a full digital PLL and somewhat less trouble with spurs and
sidebands. Tuning between the digital steps is by varying the VXO
used in the down conversion osc. It allows me to use older PLL
chips that have /n counter that only count to 255 or maybe 512.


Allison
KB1GMX

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

--- In BITX20@..., "pgdaulton" <k5wms@a...> wrote:

... have different shapes. shunt is used for Lsb series for usb.

enjoy!
PAUL DAULTON

PS HIT WRONG KEY AND SENT BEFORE MSG FINISHED

That's was a good article however there have been more written since.
The ARRL publication Experimental Methods In RF design has a far more
complete (for one place) treatment and a complete list of citationas
and references. Worth having. Also BITx traces it's origin to the
EMRFD.

FYI it's possible by selection of values to build a series filter for
either USB or LSB or even symetrical. At 6-8 crystals and symetric
shape using constants for gausian to 6db yeilds a very nice filter.


Allison

LET ME TRY AGAIN SOMETHING HAPPENED TO FIRST MSG

THOSE OF YOU WHO ARE INTERESTED IN FILTER DESIGN PLEASE CHECK
THIS SITE. www.aade.com/filter32/dishal.htm

THE AUTHOR, JOHN PIVNICHY, WROTE AN EXCELLENT ARTICLE IN JAN1993
73 MAGAZINE DESCRIBING TWIN FILTERS FOR USB AND LSB. HE IS ALSO
THE AUTHOR OF "LADDER CRYSTAL FILTERS" PUBLISHED BY MFJ ENTERPRIZES,
STARKVILLE, MS.

THE BASIC PREMISE OF THE AUTHORS WORK IS THAT SHUNT AND SERIES FILTERS
HAVE DIFFERENT SHAPES SHUNT BEING BEST FOR LSB AND SERIES FOR USB.
HIS WORK ALSO MOVES THE FILTERS SO THAT BOTH HAVE A COMMON INTERCEPT
AND USE SINGLE CARRIER FREQ FOR BOTH.

INCLUDED IN THIS SITE IS A LINK TO FREE DOWNLOAD OF FILTER DESIGN
SOFTWARE.

ENJOY AND LEARN

PAUL DAULTON K5WMS

... have different shapes. shunt is used for Lsb series for usb.

enjoy!
PAUL DAULTON

PS HIT WRONG KEY AND SENT BEFORE MSG FINISHED

THOSE INTERESTED IN FILTR DESIGN PLEASE CHECK OUT THIS SITE
www.aade.com/filter32/dishal.htm

included in this site is a link to a filter analysis program
on the aade site.

the author of this, John Pivnichy , wrote an excellent article in Jan
1993 73Magazine and abook "Ladder Crystal Filters" published by
mfj enterprizes, Starkville MS.

The basic premise of Pivnichy's work is shunt and series filters

--- In BITX20@..., "eb7hpm" <msraya@t...> wrote:

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

Two problems:

The board pattern is on the wrong side (pattern
is on top not bottom.) To use it (I may not)
the parts must be placed on foil side!

You are sure? I don't know, but if it is, what a problem!

Yes, Mr Farhan stated it as so. Minor problem. It is important
to those building to avoid runing a part.

No information on parts location on the board.
A picture of the assembled board or an overlay
would be helpful.

You can try my "manual overlay". It is located in the group files
section, here:

pPrbXMZgXY2_vH6pqJs-e9G2bWPeL7M7n38dFFLCLpj1CpS-lP_N/BITX%20PCBs%20%

Found it!

FYI: I have one operational with many mods but not build using a PCB.
The construction is dead bug on ground plane. Works very well after mods.

The one I'm doing with FAR PCB is for 6m.

Allison

I do not speak Dutch so translation may be needed.

One things I note is that the balanced modulator is not
terminated for AF of the RF side (going to the IF) and
marginal bypass for RF at the audio port.

Several people suggest and testing on mine confirms:

Provide DC and low RF bypass fro balanced modulator:
22uH choke (10-47uH ok) from balance resistor to ground.

Bypass RF into audio:
22uH choke (10 to 500uH ok) inserted from the junction
of .001uF to the intersection of capacitors from Q4 and Q10.
Add .001uF capacitor from the junction of the capacitors
from Q4 and Q10 to ground.

Thses changes prevent wideband (audio through RF) noise from
the IF amplifier from passing all the way to the audio amplifier
Q4.

Allison
KB1GMX


--- In BITX20@..., pe1abe <pe1abe@p...> wrote:

Hallo Cris potmeter regelt het audio prima maar als ik deze helemaal

los draai komt er veel ruis uit de luidspreker dit komt door
transistor q4.Als ik ic1 alleen spanning geef heb ik dat niet.Als ik
q4 ook spanning geef krijg ik die ruis (de rest van de schakeling heb
ik dan spannings loos)Het audio niveau zou ook wel iets hoger kunnen
naar mij idee.

----- Original Message -----
From: vdberghak
To: BITX20@...
Sent: Saturday, July 09, 2005 1:22 PM
Subject: [BITX20] Re: noise


Arjan,
I do not understand what you ask. You may try it in the Dutch

language.

Ik begrijp dat je vraagt of het normaal is dat er veel ruis uit de
ontvanger komt. Aan je vraagstelling maak ik op dat je dit niet

normaal

vindt. Waarom zou dat niet normaal zijn? Als je aan de volume

potmeter

draait, varieert dan ook het volume? Neem anders deel voor deel

los om

vast te stellen waar de ruis ontstaat. Met vriendelijke groet,
Chris.

--- In BITX20@..., "Arjan" <pe1abe@p...> wrote:
> I have a question I the reception rx working of my BITX20 only I
> well many noise on my audio this normal? can someone help me?
> greeting Arjan pe1abe

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YAHOO! GROUPS LINKS

a.. Visit your group "BITX20" on the web.

b.. To unsubscribe from this group, send an email to:
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c.. Your use of Yahoo! Groups is subject to the Yahoo! Terms of

Service.

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

Two problems:

The board pattern is on the wrong side (pattern
is on top not bottom.) To use it (I may not)
the parts must be placed on foil side!

You are sure? I don't know, but if it is, what a problem!

No information on parts location on the board.
A picture of the assembled board or an overlay
would be helpful.

You can try my "manual overlay". It is located in the group files
section, here:

pPrbXMZgXY2_vH6pqJs-e9G2bWPeL7M7n38dFFLCLpj1CpS-lP_N/BITX%20PCBs%20%
28Printed%20Circuit%20Boards%29/bitx_component_placing.jpg

Good bitxing...
73s
Manuel
EB7HPM/EC7ALV

--- In BITX20@..., Rob Frohne <frohro@w...> wrote:

Hi All,

I had some surplus 6 MHz crystals here, and so I'm using that as an
IF. If I use the 50 ohm termination impedance that Fahran has set
up, the filter ripple is more than 10 dB in the passband. (It should
be better with a 10 MHz IF.) If I can raise the termination
impedance it helps a lot on the ripple. It is harder to keep the
high frequency response with the higher impedances I'm trying to use
as well.

One possible solution is terminate the filter at 200ohms and use
a 4:1 balun at each end. That yeilds a 50ohm interface to the
amplifiers and allows a filter at a more reasonable impedence.

FYI: you may consider a 5:1 or even as high as 9:1 ferrite loaded
transformer as at 6mhz my experiments with filters for SSB passband
indicated a 400-500ohm termination was more redially achievable
and gave better shape factors with less ripple. The losses in the
transformers are small and can result in lower losses in the filter
at a more workable terminating impedence.

Allison
KB1GMX

--- In BITX20@..., Rob Frohne <frohro@w...> wrote:

Hi All,

I have been doing some Spice simulations, and after playing around
with it a bit, it is evident that using microwave transistors will
improve things a lot over the HF general purpose transistors. The
culprit is C sub mu, the capacitance between the collector and the
base due to the reverse biased collector base junction. The problem
is made worse by having both the transmit and receive transistors
capacitance in parallel. This provides more parallel current
feedback than we want at higher frequencies. Simulating using
microwave transistors shows that the 50 ohm input impedance goes up
to almost 100 MHz, but with the general purpose HF transistors, you
only get to a very maximum of 10 MHz (often less), and then the
C sub mu messes things up.

That is indeed true but in practice transistors like the 2n3904
and 2n/pn2222A easily perfom to 20+ mhz. These devices have a
FT or 300-350mhz. A rule of thumb is to stay below FT/10 for
predictable feedback amplifier operation at medium gains. For
example 2n3904 has Ft of 300mhz (min) and nominal HFE of 100
at low frequencies or DC. At 30mhz the effective AC hfe is
only 10 so gains of greater than 10 (20db voltage) are not
likely with broadband circuits. This is due not only to C-B
feedback but also C-E capacitance. The bias currents, working
impedences and feedback amounts do interact. At lower impedences
(50 input and 50 to 200ohm output) the devices perform well.
Even with small degradation the cost of these devices are often
un the less than 10 cents(US) range make them attractive. I usually
source 2n3904, 2n3906, PN2222 types in quantities of 20 for 6
cents(US) each.

So for this design based on experience devices in the 2n3904 and
2222 are good for the IF, LO and maybe the RF up to 20m (14mhz).
A device like the 2n5179 would be advised for the RF amp(Q1)as
is both lower noise and has an FT in excess of 1ghz. Others
that work well are 2N3866, 2n5109, 2sc2570. Devices characterized
for CATV use are excellent.

Things to look for in an IF transistor for this circuit, good HFE at
10-20ma (over 100 is advised). An FT of not less that 300mhz is
adaquate and there are many 2n, and 2SC devices that easily meet
this.

For the RF amp (Q1) the noise figure of the transistor is important.
most good VHF and uhf devices are low noise. However the 2n3904
is surprizingly good (typical 4-5db) for low (below 20mhz) HF use.

I've used 2n3904, 2n2222A with excellent results as high
as 40mhz for circuits such as IF amp, buffer amplifiers and
general use wide band amplifier to 30mhz. Another device the
2n4124 has been used for 6m as amplifier(wideband) and oscillator.
The trick if there is any is recognizing that trying to achieve more
gain at working frequncy than the device will resonably yeild is
moving toward instability and requires a different topology than a
wideband feeback amplifier, or a better device.

An aside: if you going to analyse the amplifiers also anaylyse their
interaction with the crystal filter. You will find that there are
other first order and second order effects as the filter band edges
are approaced and the balanced mixers are not overly fond of
mistermination. These are as significant as C sub mu interactions.
One of the ugly facts of feedback amplifiers as used is that output
impedence interacts with input impedence (and also reverse) and as a
result gain also changes. Crystal filters as you approach band edges
and out of band undergo significant changes in termination phase and
resistance.


Allison,
KB1GMX {in any project there is: Good, Fast, Cheap, pick any two.}

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