Date   
Re: Off topic: A New Blog

pgdaulton <k5wms@...>
 

--- In BITX20@..., "ashhar_farhan" <farhan@...> wrote:

I have started a new blog on http://straightkey.blogspot.com/. where i
will rant about homebrewing in general. in the first post today, i
discuss setting up a reasonable home lab.
ASSHAR THANKS FOR SETTING UP THE NEW BLOG.I'VE ENJOYED
BUILDING TWO OF YOUR BITX RIGS, BUT I VALUE THE KNOWLEDGE
GAINED FROM THE YAHOO GROUP EVEN MORE.

I GET SOME ARGUEMENT FORM OTHERS BUT I THINK AMATEUR RADIO
EXISTS FOR "EDUCATION AND RECREATION" EMPHASIS ON EDUCATION

HOPE I CAN CONTRIBUTE TO THE NEW SITE.

PAUL DAULTON K5WMS

Re: Off topic: A New Blog

wimmie262000 <wvh@...>
 

Wow, did you connect your old Teletype to the Internet? ;-)

Re: Off topic: A New Blog

Bernard MOUROT
 

----- Original Message -----
From: wimmie262000
To: BITX20@...
Sent: Wednesday, May 30, 2007 5:01 PM
Subject: [BITX20] Re: Off topic: A New Blog


Wow, did you connect your old Teletype to the Internet? ;-)





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Off topic again: A direct conversion receiver

farhan@...
 

I have posted a simple direct conversion receiver on my blog.
you can view the post on straightkey.blogspot.com. the receiver's write up in on phonestack.com/farhan/dc40.html.

the reason for this post is that the audio section of this receiver might be a good substitute for the audio section of the bitx20.

- farhan

Re: Off topic again: A direct conversion receiver

Greg W:-) <onegammyleg@...>
 

Thanks , that looks like a neat little project.

But , is it just me, or does Yahoo deliberately break the links in
emails now with spaces.??
I have seen it a quite a few times on my mail outs from various groups
the links have extra spaces added in them , that of course breaks the
link.

For example ,, as shown in my delivered email today was - straightkey.
blogspot. com

GRRRR !

gregW:-) OH2FFY


http://www.swdxer.co.nr/
=====================================================================

--- In BITX20@..., farhan@... wrote:


I have posted a simple direct conversion receiver on my blog.
you can view the post on straightkey.blogspot.com. the receiver's
write up
in on phonestack.com/farhan/dc40.html.

the reason for this post is that the audio section of this receiver
might
be a good substitute for the audio section of the bitx20.

- farhan

Re: Off topic again: A direct conversion receiver

Arv Evans
 

Greg

It is the [CR] that is inserted when a URL is continued on the following
line. Yahoo takes the "." part of a URL as a potential line-break at
the end of a sentence and sometimes adds the [CR] to make the line fit
display width constraints. You have to watch for these and simply put
the whole URL back together before you use it.

Arv
_._

Greg W:-) wrote:


Thanks , that looks like a neat little project.

But , is it just me, or does Yahoo deliberately break the links in
emails now with spaces.??
I have seen it a quite a few times on my mail outs from various groups
the links have extra spaces added in them , that of course breaks the
link.

For example ,, as shown in my delivered email today was - straightkey.
blogspot. com

GRRRR !

gregW:-) OH2FFY

http://www.swdxer.co.nr/ <http://www.swdxer.co.nr/>
=====================================================================

--- In BITX20@... <mailto:BITX20%40yahoogroups.com>,
farhan@... wrote:


I have posted a simple direct conversion receiver on my blog.
you can view the post on straightkey.blogspot.com. the receiver's
write up
in on phonestack.com/farhan/dc40.html.

the reason for this post is that the audio section of this receiver
might
be a good substitute for the audio section of the bitx20.

- farhan

Re: Off topic again: A direct conversion receiver

pe1rco
 

--- In BITX20@..., farhan@... wrote:
Hi there
It's a look a like of the R1 dc reciever from rick campbel
kk7b
you can also find look a like's on http://www.qrp.pops.net-default.htm
greatins
alex pe1rco

I have posted a simple direct conversion receiver on my blog.
you can view the post on straightkey.blogspot.com. the receiver's
write up
in on phonestack.com/farhan/dc40.html.

the reason for this post is that the audio section of this receiver
might
be a good substitute for the audio section of the bitx20.

- farhan

Re: Off topic again: A direct conversion receiver

pe1rco
 

--- In BITX20@..., "pe1rco" <alkotte@...> wrote:
sorry http//www.qrp.pops.net/default.htm
--- In BITX20@..., farhan@ wrote:
Hi there
It's a look a like of the R1 dc reciever from rick campbel
kk7b
you can also find look a like's on http://www.qrp.pops.net-
default.htm
greatins
alex pe1rco

I have posted a simple direct conversion receiver on my blog.
you can view the post on straightkey.blogspot.com. the receiver's
write up
in on phonestack.com/farhan/dc40.html.

the reason for this post is that the audio section of this
receiver
might
be a good substitute for the audio section of the bitx20.

- farhan

Re: Off topic again: A direct conversion receiver

pe1rco
 

--- In BITX20@..., "pe1rco" <alkotte@...> wrote:
http://www.qrp.pops.net/default.htm
sorry it was a little early on this side
--- In BITX20@..., "pe1rco" <alkotte@> wrote:
sorry http//www.qrp.pops.net/default.htm
--- In BITX20@..., farhan@ wrote:
Hi there
It's a look a like of the R1 dc reciever from rick campbel
kk7b
you can also find look a like's on http://www.qrp.pops.net-
default.htm
greatins
alex pe1rco

I have posted a simple direct conversion receiver on my blog.
you can view the post on straightkey.blogspot.com. the
receiver's
write up
in on phonestack.com/farhan/dc40.html.

the reason for this post is that the audio section of this
receiver
might
be a good substitute for the audio section of the bitx20.

- farhan

Re: Off topic again: A direct conversion receiver

n7ve <dan.Tayloe@...>
 

When I think of a good audio stage, particularly for a DC receiver,
two things immediately come to mind:

1) Audio selectivity - This is not as important in my case since my
hearing is shot, but for folks with more normal hearing, it would be
nice to have at least some audio roll off beyond ~2.5 KHz (SSB). Some
folks (not me) can hear out to 20 KHz.

2) Feedback - Feedback reduces distortion, provides a means for
generating reproducible, device independent gain, and helps insure
clean audio. Clean audio and reproducible stage gain are good things
in a design that is going to be shared with others.

It only takes a few more parts to address these two issues.

- Dan

Re: Off topic again: A direct conversion receiver

farhan@...
 

dan is spot on, as usual. let me add some more fuel to this fire.

there are two approaches to a radio project:
1. where you put a resource limitation upon yourself (ex:less than 10 transistors). quite similar to what hitchcock did in his movies ('i will shoot an entire movie through one window'). this stresses your engineering skills in a certain way.
2. where you say, given my test gear and my junk box, what is the best I can do?

So, my comments are from the second category.

i would want an audio amplifier with really loud capability with the volume turned way down low. this will keep the audio dynamic range wide enough for me to be able to discern the weak signals against my thumping neighbours within the receiver's filter's passband. i usually use a good audio amplifier tapped right out of my auio pre-amp. at the moment, the shack has Bose companion 2 system as the standard bench audio. try connecting your stereo to your radio. you will have difficulty going back to the LM386.

second, i would prefer a class-A audio output. an ideal amp would be a low noise op amp driving an emitter follower in class A. It will sure suck a lot of power, but the audio will be amazing. an alternative is to use a valve amp. the sound is really sweet (something to do with the even harmonics being way below the odd harmonics). I have often used my guitar amp (an EL84) with the rigs.

Use a big speaker with a nice mid range and a nice baffle. one of the main reasons one can forward for a big receiver chassis is it can act as a good speaker enclosure.

- farhan

On Wed, 6 Jun 2007, n7ve wrote:

When I think of a good audio stage, particularly for a DC receiver,
two things immediately come to mind:

1) Audio selectivity - This is not as important in my case since my
hearing is shot, but for folks with more normal hearing, it would be
nice to have at least some audio roll off beyond ~2.5 KHz (SSB). Some
folks (not me) can hear out to 20 KHz.

2) Feedback - Feedback reduces distortion, provides a means for
generating reproducible, device independent gain, and helps insure
clean audio. Clean audio and reproducible stage gain are good things
in a design that is going to be shared with others.

It only takes a few more parts to address these two issues.

- Dan





About good audio

Dimitri Aguero <daguero@...>
 

People seeking good audio may want to take a look at the TDA2003 configured
with very little gain. The sound quality is excellent.

I used it in a regenerative receiver by F5LVG, and the audio that came from
broadcast was quite close to FM sound quality.

73 Dimitri F4DYT

Re: About good audio

Arv Evans
 

I use LM380 AF amplifiers on my BITX20 constructions. This
modification was very easy to implement.

Arv - K7HKL


Dimitri Aguero wrote:


People seeking good audio may want to take a look at the TDA2003
configured
with very little gain. The sound quality is excellent.

I used it in a regenerative receiver by F5LVG, and the audio that came
from
broadcast was quite close to FM sound quality.

73 Dimitri F4DYT



Re: About good audio

Ron Brink <pa2rf@...>
 

Hi Dimitri,
For my BITX17 (derivative of the BITX20) I have used an LA4185 chip which I found in an old transistor radio and by coincidence found the datasheet on the internet. See my website, picture 12, for circuitdiagram of this chip
http://home.versatel.nl/laar60/BITX17.htm
I am quite happy with the max 4 Watts (a whole lot of audio that is!) coming from this IC. Much more comfortable than the LM386. And yes the TDA2003 should work fine as well.

73 de Ron
PA2RF



Dimitri Aguero wrote:

People seeking good audio may want to take a look at the TDA2003
configured
with very little gain. The sound quality is excellent.

I used it in a regenerative receiver by F5LVG, and the audio that came
from
broadcast was quite close to FM sound quality.

73 Dimitri F4DYT










---------------------------------
Fussy? Opinionated? Impossible to please? Perfect. Join Yahoo!'s user panel and lay it on us.

Re: About good audio

Rahul Srivastava
 

Hi!
Many commercial rigs still use Tda2002/3 chips at a lower gain.
73
Rahul VU3WJM



Arv Evans <arvid.evans@...> wrote:
I use LM380 AF amplifiers on my BITX20 constructions. This
modification was very easy to implement.

Arv - K7HKL

Dimitri Aguero wrote:

People seeking good audio may want to take a look at the TDA2003
configured
with very little gain. The sound quality is excellent.

I used it in a regenerative receiver by F5LVG, and the audio that came
from
broadcast was quite close to FM sound quality.

73 Dimitri F4DYT










---------------------------------
Yahoo! Answers - Get better answers from someone who knows. Tryit now.

Operating IRF510 at 33 volts for 15 watts?

joymukherji2001
 

Hi Guys,
excellent site ! revolutionary design that is BITX!

I am designing an easy to build dsb transmitter for neophytes in
homebrew construction.I will use 2n2222 pushpull stage to drive the
IRF510 final.My question is what standing current I should use at 33
Volts? I know Farhan uses 80 ma at 12 volts. Is it really possible to
get 15 watts out of the PA stage? I am going to experiment soon once my
components arrive in mail.

Thanks a lot!

73's

Joy

Re: Operating IRF510 at 33 volts for 15 watts?

Arv Evans
 

Joy

You should probably design the inductors (current carrying capacity and
core saturation) for something around 50 watts if you are going to run
the IRF510 on 33 volts. Be sure to use adequate heat sinks.

In prototype work on the Hendricks QRP Kits BITX20A we are using a
push-pull IRF510 final with 12 volts Vcc. By lowering the drain
impedance it is easy to get 15 watts output with no RF compression, and
20+ watts with some compression in the input versus output of the final.

By adjusting the RF drive level and using a scope to compare input
waveform with output waveform you can adjust idling current for the
setting that gives best linearity at all input levels.

Since IRF devices are intended by the manufacturer to be for switching
applications, the datasheet does not show necessary information for
running these as linear amplifiers. You have to determine that
experimentally.

Arv - K7HKL


joymukherji2001 wrote:


Hi Guys,
excellent site ! revolutionary design that is BITX!

I am designing an easy to build dsb transmitter for neophytes in
homebrew construction.I will use 2n2222 pushpull stage to drive the
IRF510 final.My question is what standing current I should use at 33
Volts? I know Farhan uses 80 ma at 12 volts. Is it really possible to
get 15 watts out of the PA stage? I am going to experiment soon once my
components arrive in mail.

Thanks a lot!

73's

Joy

Re: Operating IRF510 at 33 volts for 15 watts?

Bernard MOUROT
 

No problem at 24 Volts puspull IRF510 50 Watts RF out 7 and 3.5 MHz , the problème is impédanz adaptation and out put to antenne in 14 MHz. (Center feed and Mac Yoy coupling system)
Probleme from Ferrite correct Al ; binoculare BN4312 is not OK in French , Tore and self rapport is principal problem..
output in CW 20 Watts RF at 13.8 V ROS is 1/1, SSB, variable modulation ROS is varalble 1 /1 To 1/1.5 floatting impédanz !
sorry
73

F6BCU

----- Original Message -----
From: Arv Evans
To: BITX20@...
Sent: Thursday, June 14, 2007 7:42 PM
Subject: Re: [BITX20] Operating IRF510 at 33 volts for 15 watts?


Joy

You should probably design the inductors (current carrying capacity and
core saturation) for something around 50 watts if you are going to run
the IRF510 on 33 volts. Be sure to use adequate heat sinks.

In prototype work on the Hendricks QRP Kits BITX20A we are using a
push-pull IRF510 final with 12 volts Vcc. By lowering the drain
impedance it is easy to get 15 watts output with no RF compression, and
20+ watts with some compression in the input versus output of the final.

By adjusting the RF drive level and using a scope to compare input
waveform with output waveform you can adjust idling current for the
setting that gives best linearity at all input levels.

Since IRF devices are intended by the manufacturer to be for switching
applications, the datasheet does not show necessary information for
running these as linear amplifiers. You have to determine that
experimentally.

Arv - K7HKL

joymukherji2001 wrote:
>
> Hi Guys,
> excellent site ! revolutionary design that is BITX!
>
> I am designing an easy to build dsb transmitter for neophytes in
> homebrew construction.I will use 2n2222 pushpull stage to drive the
> IRF510 final.My question is what standing current I should use at 33
> Volts? I know Farhan uses 80 ma at 12 volts. Is it really possible to
> get 15 watts out of the PA stage? I am going to experiment soon once my
> components arrive in mail.
>
> Thanks a lot!
>
> 73's
>
> Joy
>
>

[Non-text portions of this message have been removed]





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Ce programme a supprimé2076 d'e-mails spam à ce jour.
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New Photos

anil_k_raj <anil_k_raj@...>
 

Arv, I can see that you've uploaded photos of your progress with the
Hendricks kit. What is the PCB size now, has it changed compared to
earlier versions? Also does it retain the possibility to feed the
board with an external DDS?
Best 73s
Anil

Re: Operating IRF510 at 33 volts for 15 watts?

joymukherji2001
 

Arv,
hmmm...interesting
I want to feed the PA 33 volts because then it is going to be easy on
inductors as they will be carrying much less current than they would
on 12 volts supply.

Pushpull configuration is quite attractive as it will give better
linearity but I want to keep things simple by using single ended
IRF510 delivering 15 watts and probably 13 watts after low pass
filter.

So as per your comments it is possible to get 15 watts from a single
fet stage.I am happy to hear that and will experiment with the
standing current for acceptable linearity.

73,s
Joy


--- In BITX20@..., Arv Evans <arvid.evans@...> wrote:

Joy

You should probably design the inductors (current carrying capacity
and
core saturation) for something around 50 watts if you are going to
run
the IRF510 on 33 volts. Be sure to use adequate heat sinks.

In prototype work on the Hendricks QRP Kits BITX20A we are using a
push-pull IRF510 final with 12 volts Vcc. By lowering the drain
impedance it is easy to get 15 watts output with no RF compression,
and
20+ watts with some compression in the input versus output of the
final.

By adjusting the RF drive level and using a scope to compare input
waveform with output waveform you can adjust idling current for the
setting that gives best linearity at all input levels.

Since IRF devices are intended by the manufacturer to be for
switching
applications, the datasheet does not show necessary information
for
running these as linear amplifiers. You have to determine that
experimentally.

Arv - K7HKL


joymukherji2001 wrote:

Hi Guys,
excellent site ! revolutionary design that is BITX!

I am designing an easy to build dsb transmitter for neophytes in
homebrew construction.I will use 2n2222 pushpull stage to drive
the
IRF510 final.My question is what standing current I should use at
33
Volts? I know Farhan uses 80 ma at 12 volts. Is it really
possible to
get 15 watts out of the PA stage? I am going to experiment soon
once my
components arrive in mail.

Thanks a lot!

73's

Joy