Cheap and performant CW Xtal filter for Ubitx
A tight 430 Hz filter matched to 50 ? made with standard 12 MHz crystals HC49/U-S +/- 30 ppm.
?A batch of 20 crystals was sorted in series resonance frequency at phase 0¡ã.
Five crystals were selected within an interval of 100 Hz maximum. The highest in frequency affected at Q3, then others are placed at Q2, Q4, Q1 and Q5 to the lowest frequency. Casings are soldered to the ground plane. C0G ceramic capacitor are preferred to X7R and placed on bottom face.
Measured average parameters?: Fs = 11,9997.180 kHz
L1 = 17.484 mH?????? C1 = 10.0 fF? ??????????? R1 = 11.1 ?? ??????????? C0 = 4.1 pF
?
Center capacitors were calculated with the help of this application :
C1 and C2 were determined practically with vector network analyzer.
?
Filter measurement of the prototype : matched to 50 ?
CF = 11,9997.575 kHz?????? S21 = -8.5 dB ????????? S11 < -15 dB
BW = 434 Hz ??@ -6 dB
BW = 1680 Hz @-60 dB
Insertion loss depends on the ratio between series resistance of crystals R1 and characteristic transfer impedance at 50 ?. This ratio determines filter bandwidth too !
?73 de F5RCT
   
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Re: Carrier Null revisited
This being a new board out of the box I would check the dual diode package for a possible diode fail condition. Also, checking solder on the legs of the chip and any possible shorts that might have been missed in production. You may have one good diode and one failed within the package. Good luck and 73's Dale
On Tue, Oct 31, 2017 at 1:46 PM, Jerry Gaffke via Groups.Io <jgaffke@...> wrote: AM phone without any modulation is just a carrier, like a CW transmission.
AM phone modulated with a continuous 1khz tone has that carrier plus two sidebands,
one sideband that's 1khz above the carrier and one that's 1khz below the carrier
If you had a very selective receiver, you could tune in one of those sidebands and it would be just like a carrier,
or CW transmission (assuming we are still modulating with a 1khz continuous tone).
For single sideband, we filter out all but one of those sidebands with the crystal filter before sending it out the power amp.
That sideband only has power out over the air when modulation is present.
Jerry
On Tue, Oct 31, 2017 at 12:33 pm, Arvo KD9HLC wrote:
A little help understanding here would be appreciated.
A given TX on AM or SSB would have an amplitude envelope proportional to the modulated audio signal, right?
What is the amplitude of that signal if there is no audio excitation?? I wouldn't expect zero.? I would key a shorted mic and there would be some carrier with no amplitude modulation.
If we were looking at the math, the output of the TX would be something like, A*sin f + C, where C would be the signal with no one talking into the mic, right?
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Re: Carrier Null revisited
On Tue, Oct 31, 2017 at 12:33 pm, Arvo KD9HLC wrote:
What is the amplitude of that signal if there is no audio excitation?? I wouldn't expect zero.? I would key a shorted mic and there would be some carrier with no amplitude modulation.
In SSB the carrier (as well as one of the side bands) are suppressed so theoretically the amplitude would be zero if there is no audio excitation. However in practice complete carrier cancellation is never accomplished - most commercial rigs have at least 40dB suppression. 73 Allard PE1NWL
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Re: Arduino USB cable extension ???
I found:
/g/BITX20/message/30044
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Re: Carrier Null revisited
AM phone without any modulation is just a carrier, like a CW transmission.
AM phone modulated with a continuous 1khz tone has that carrier plus two sidebands,
one sideband that's 1khz above the carrier and one that's 1khz below the carrier
If you had a very selective receiver, you could tune in one of those sidebands and it would be just like a carrier,
or CW transmission (assuming we are still modulating with a 1khz continuous tone).
For single sideband, we filter out all but one of those sidebands with the crystal filter before sending it out the power amp.
That sideband only has power out over the air when modulation is present.
Jerry
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Show quoted text
On Tue, Oct 31, 2017 at 12:33 pm, Arvo KD9HLC wrote:
A little help understanding here would be appreciated.
A given TX on AM or SSB would have an amplitude envelope proportional to the modulated audio signal, right?
What is the amplitude of that signal if there is no audio excitation?? I wouldn't expect zero.? I would key a shorted mic and there would be some carrier with no amplitude modulation.
If we were looking at the math, the output of the TX would be something like, A*sin f + C, where C would be the signal with no one talking into the mic, right?
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Arduino USB cable extension ???
Hello.
Does an OM use a USB cable that would connect the Raduino to the back of the case ?
This is to avoid removing the cover at each update.
I think I read a post on the subject but I can not find.
Thank you and 73.
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Re: Carrier Null revisited
Good Afternoon, All.
A little help understanding here would be appreciated.
A given TX on AM or SSB would have an amplitude envelope proportional to the modulated audio signal, right?
What is the amplitude of that signal if there is no audio excitation?? I wouldn't expect zero.? I would key a shorted mic and there would be some carrier with no amplitude modulation.
If we were looking at the math, the output of the TX would be something like, A*sin f + C, where C would be the signal with no one talking into the mic, right?
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Re: Carrier Null revisited
Might be easier to work on the bitx40 than you think.
Have you tried?
I find the 1206 C's and R's much easier to work with than through-hole parts, using two soldering irons to remove them.
On that sot23 diode, heat up the single pin on one side, solder wick away excess solder, then pry it up with an xacto knife.
Then do the same with the other two pins.
Replace with axial lead 1n4148's and a pot of your choice as shown in the schematic.
You do need good light, good magnification, and no coffee.
Or perhaps a young assistant who might have a vague interest in becoming a radio amateur.
At $59, this is all way easier and cheaper than the typical SSB kit.
Was developed in part as a way to encourage hams to get out a soldering iron and hack at it.
Jerryd
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On Tue, Oct 31, 2017 at 07:16 am, Grayson Evans wrote:
The problem with this board is if there is something wrong there is no way I can repair or modify it. Ultra small surface mount is not my idea of fun.
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Re: Carrier Null revisited
I ran some math on your measurements, assuming 5 W maximum output and your carrier would be right near 30 db down. for comparison, an older model ICOM-28 was specified to have at least 40 db carrier suppression, so for an inexpensive home brew rig this isn't terrible. Perhaps with a matched set that could be nulled you could do better if you needed. gordon ________________________________________ From: [email protected] < [email protected]> on behalf of Grayson Evans <wa4gvm@...> Sent: Tuesday, October 31, 2017 10:15 AM To: [email protected]Subject: Re: [BITX20] Carrier Null revisited OK will check. I checked the carrier output (no mic and the PTT grounded). I get about 1.5V p-p into a dummy load. That equates to about 5 mW. Not much, but enough to make a CW contact by keying the PTT line! Maybe Ill convert it to CW! The problem with this board is if there is something wrong there is no way I can repair or modify it. Ultra small surface mount is not my idea of fun. Grayson On Oct 30, 2017, at 10:57 PM, Raj vu2zap <rajendrakumargg@...> wrote:
Grayson,
Measure the DC voltage in both RX and TX modes across C107. It should be zeroif not you will have a carrier
leak.
You complaint that external modulation sounds bad could be something related to the above or simply that
in close proximity you will hear mains hum modulating a carrier. Try a QSO with some near by ham and see.
Raj
At 31/10/2017, you wrote:
So i heard about the diode/pot replacement, but I can?€?t even find the dual diode on the board or where R105 used to be.
I am keying the transmitter into a dummy load and monitoring with a scope. I am also listening on a Collins receiver with its antenna disconnected. The carrier seems way to high but I didn?€?t write down the exact voltage on the scope. The receiver across the room shows an S9 with no antenna, but the metal enclosure on the BiTX is open, so a lot of signal escaping.
Also, the audio sounds terrible from the little crystal mic. I injected a 20mV 400 cycle tone into the mic input just to see if it was the mic. The tone also sounds terrible. Sounds like the tone is modulated with another low frequency (I checked DC supply and its clean).
I was going to do some signal following with the scope, but I have a heck of a time trying to identify where the components are on the board. In another post I asked if anyone has a board layout drawing. There is one somewhere but not on Farhans site.
Thanks
KJ7UM Grayson
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Re: Instructions for using the Raduino v1.26 (PE1NWL) in French.
#bitx40help
Hi Sarma,
thanks for the suggestion, I will consider your idea for auto band
switching in raduino v2.
However even if we offer auto band switching, I believe most ops would
still want to have an additional manual switch or button. Because it
allows for quick band switching without having to turn the dial all the
way up or down just to switch bands.
73 Allard PE1NWL
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On Tue, October 31, 2017 15:06, Mvs Sarma wrote: hi Allard,
I suppose that following procedure could be implementable for a possible
2
band working.
Initially the VFO would start with 40m band with LSB and 10/12MHz BFO
switchable with fine adjustment.
As you go to end of the band , it could perhaps aumatically switch over
to
20m with usb , and same selectable VFO , BUT now th LPF can be switched by
a relay.
There might not be any need for any extra button for band change.
On e way down from 20m
if some one continues to reduce below 14.00 , it could revert to 7MHz
(40m), obviously lsb and filter relay released for 40m lpf.
Thuis is wild imagination , I am nott from Software at all.Kindly study
the possibility.
regards
sarma
vu3zmv
regards
Sarma
On Tue, Oct 31, 2017 at 7:04 PM, F1NQP JanJack <f1nqp@...> wrote:
On Tue, Oct 31, 2017 at 06:19 am, Allard PE1NWL wrote:
However these are now obsolete as the si5351 library is no longer used
by
the raduino sketch. So you may want to remove this section.
Hello Allard.
No library is to install?
I can delete everything related to the installation of libraries?
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Re: Carrier Null revisited
OK will check.
I checked the carrier output (no mic and the PTT grounded). I get about 1.5V p-p into a dummy load.
That equates to about 5 mW. Not much, but enough to make a CW contact by keying the PTT line!
Maybe Ill convert it to CW!
The problem with this board is if there is something wrong there is no way I can repair or modify it. Ultra small surface mount is not my idea of fun.
Grayson
toggle quoted message
Show quoted text
On Oct 30, 2017, at 10:57 PM, Raj vu2zap <rajendrakumargg@...> wrote:
Grayson,
Measure the DC voltage in both RX and TX modes across C107. It should be zeroif not you will have a carrier
leak.
You complaint that external modulation sounds bad could be something related to the above or simply that
in close proximity you will hear mains hum modulating a carrier. Try a QSO with some near by ham and see.
Raj
At 31/10/2017, you wrote:
So i heard about the diode/pot replacement, but I can?€?t even find the dual diode on the board or where R105 used to be.
I am keying the transmitter into a dummy load and monitoring with a scope. I am also listening on a Collins receiver with its antenna disconnected. The carrier seems way to high but I didn?€?t write down the exact voltage on the scope. The receiver across the room shows an S9 with no antenna, but the metal enclosure on the BiTX is open, so a lot of signal escaping.
Also, the audio sounds terrible from the little crystal mic. I injected a 20mV 400 cycle tone into the mic input just to see if it was the mic. The tone also sounds terrible. Sounds like the tone is modulated with another low frequency (I checked DC supply and its clean).
I was going to do some signal following with the scope, but I have a heck of a time trying to identify where the components are on the board. In another post I asked if anyone has a board layout drawing. There is one somewhere but not on Farhans site.
Thanks
KJ7UM Grayson
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Re: Instructions for using the Raduino v1.26 (PE1NWL) in French.
#bitx40help
hi Allard,
?I suppose that following procedure could be implementable for a possible 2 band working. ?Initially the VFO would start with 40m band with LSB and 10/12MHz BFO switchable with fine adjustment. ?As you go to end of the band , it could perhaps aumatically switch over to 20m with usb , and same selectable VFO , BUT now th LPF can be switched by a relay. There might not be any need for any extra button for band change. On e way down from 20m ?if some one continues to reduce below 14.00 , it could revert to 7MHz (40m), obviously lsb and? filter relay released for 40m? lpf. ?Thuis is wild imagination , I am nott from Software at all.Kindly study the possibility.
On Tue, Oct 31, 2017 at 7:04 PM, F1NQP JanJack <f1nqp@...> wrote: On Tue, Oct 31, 2017 at 06:19 am, Allard PE1NWL wrote:
However these are now obsolete as the si5351 library is no longer used by
the raduino sketch. So you may want to remove this section.
Hello Allard.
No library is to install?
I can delete everything related to the installation of libraries?
|
Re: Instructions for using the Raduino v1.26 (PE1NWL) in French.
#bitx40help
OK i modify my article accordingly.
Thanks again Alllard.
|
Re: Instructions for using the Raduino v1.26 (PE1NWL) in French.
#bitx40help
Since v1.20, Jerry's minimal si5351 routines are included in the sketch
code. Hence we don't need to install the si5351 library anymore.
Note that the sketch still requires some other libraries (wire, eeprom,
liquidcrystal) but these are already included in the IDE, so you won't
need to manually download and install them.
73 Allard PE1NWL
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Show quoted text
On Tue, October 31, 2017 14:34, F1NQP JanJack wrote: On Tue, Oct 31, 2017 at 06:19 am, Allard PE1NWL wrote:
However these are now obsolete as the si5351 library is no longer used
by
the raduino sketch. So you may want to remove this section.
Hello Allard.
No library is to install?
I can delete everything related to the installation of libraries?
|
Re: Instructions for using the Raduino v1.26 (PE1NWL) in French.
#bitx40help
On Tue, Oct 31, 2017 at 06:19 am, Allard PE1NWL wrote:
However these are now obsolete as the si5351 library is no longer used by
the raduino sketch. So you may want to remove this section.
Hello Allard. No library is to install?
I can delete everything related to the installation of libraries?
|
Re: Instructions for using the Raduino v1.26 (PE1NWL) in French.
#bitx40help
Dear Jean-Jacques,
thanks for the French translations.
I noticed that on this page there are still instructions for installing
the si5351 library:
Installez les biblioth¨¨ques depuis le programme Arduino:
Il va falloir maintenant installer les biblioth¨¨ques qui vont servir au
SI5351.
However these are now obsolete as the si5351 library is no longer used by
the raduino sketch. So you may want to remove this section.
73 Allard PE1NWL
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Show quoted text
On Tue, October 31, 2017 13:55, F1NQP JanJack wrote: Hello.
You will find the instructions for using the Raduino v1.26 from PE1NWL,
translated into French on my website.
(
)
So I have not yet started editing my Bitx40, but at least I have a notice
in French ;-)
73 to all.
|
Instructions for using the Raduino v1.26 (PE1NWL) in French.
#bitx40help
Hello.
You will find the instructions for using the Raduino v1.26 from PE1NWL, translated into French on my website.
So I have not yet started editing my Bitx40, but at least I have a notice in French ;-)
73 to all.
|
On Mon, Oct 30, 2017 at 08:07 am, Allard PE1NWL wrote:
While you're waiting for the delivery of the 10T pot, you can already
start with the rest of the modifications.
Although highly recommended, the 10T pot is not strictly required - the
software will still work OK with the standard supplied pot.
Thank you Allard.
I'll come here post some pictures :-)
Good day to all.
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Re: Carrier Null revisited
?e are duiscuissing around BFO carrier leak. As has been explained well that a chip dual diodes are internally balancedenough. Even if suppose one uses discrete diodes,one could minimize but not eliminate carrier leak. It is analogeous to? non exuixtance of 0 and Infinity.
The nulled carrier to one's expectation gets amplified at PA as correctly suggested by Asher Farhan.? but I suppose that we need to make relative measurements. ? sarma
?vu3zmv
?
On Tue, Oct 31, 2017 at 8:27 AM, Raj vu2zap <rajendrakumargg@...> wrote: Grayson,
Measure the DC voltage in both RX and TX modes across C107. It should be zeroif not you will have a carrier
leak.
You complaint that external modulation sounds bad could be something related to the above or simply that
in close proximity you will hear mains hum modulating a carrier. Try a QSO with some near by ham and see.
Raj
At 31/10/2017, you wrote:
>So i heard about the diode/pot replacement, but I can¡¯t even find the dual diode on the board or where R105 used to be.
>
>I am keying the transmitter into a dummy load and monitoring with a scope.? ?I am also listening on a Collins receiver with its antenna disconnected.? The carrier seems way to high but I didn¡¯t write down the exact voltage on the scope.? The receiver across the room shows an S9 with no antenna, but the metal enclosure on the BiTX is open, so a lot of signal escaping.
>
>Also, the audio sounds terrible from the little crystal mic.? I injected a 20mV 400 cycle tone into the mic input just to see if it was the mic.? The tone also sounds terrible.? Sounds like the tone is modulated with another low frequency (I checked DC supply and its clean).
>
>I was going to do some signal following with the scope, but I have a heck of a time trying to identify where the components are on the board.? In another post I asked if anyone has a board layout drawing. There is one somewhere but not on Farhans site.
>
>Thanks
>KJ7UM Grayson
|
Re: Carrier Null revisited
Grayson,
Measure the DC voltage in both RX and TX modes across C107. It should be zeroif not you will have a carrier
leak.
You complaint that external modulation sounds bad could be something related to the above or simply that
in close proximity you will hear mains hum modulating a carrier. Try a QSO with some near by ham and see.
Raj
toggle quoted message
Show quoted text
At 31/10/2017, you wrote: So i heard about the diode/pot replacement, but I can?€?t even find the dual diode on the board or where R105 used to be.
I am keying the transmitter into a dummy load and monitoring with a scope. I am also listening on a Collins receiver with its antenna disconnected. The carrier seems way to high but I didn?€?t write down the exact voltage on the scope. The receiver across the room shows an S9 with no antenna, but the metal enclosure on the BiTX is open, so a lot of signal escaping.
Also, the audio sounds terrible from the little crystal mic. I injected a 20mV 400 cycle tone into the mic input just to see if it was the mic. The tone also sounds terrible. Sounds like the tone is modulated with another low frequency (I checked DC supply and its clean).
I was going to do some signal following with the scope, but I have a heck of a time trying to identify where the components are on the board. In another post I asked if anyone has a board layout drawing. There is one somewhere but not on Farhans site.
Thanks
KJ7UM Grayson
|
Jean-Matthieu F5RCT
Allard PE1NWL
F1NQP JanJack
Arvo W0VRA
Raj vu2zap