Re: The issues of the TDA2822
How much does this cost? tim ab0wr On Wed, 28 Mar 2018 07:41:30 +0530 "John T P" <tpjohn@...> wrote: TBA810
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Jerry, My wording was bad I guess. After the 12mhz filter is where you have to do the AGC detect. You and I agree. tim ab0wr On Tue, 27 Mar 2018 19:45:06 -0700 "Jerry Gaffke via Groups.Io" <jgaffke@...> wrote: I think you have it backwards.?
No strong adjacent channel signals should be present after the 12mhz
filter. However, they are present prior to the filter.
On Tue, Mar 27, 2018 at 07:14 pm, Tim Gorman wrote:
If you don't detect AGC till after the 12Mhz filter then you risk
having strong adjacent-channel signals controlling the AGC rather
than the signal you are interested in.
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Jerry, You pretty much nailed it. While hi-tech solutions are of course important to develop, the target audience for the ubitx are probably more interested in simple modifications that anyone can implement which provide some increased functionality. tim ab0wr On Tue, 27 Mar 2018 18:40:29 -0700 "Jerry Gaffke via Groups.Io" <jgaffke@...> wrote: Detecting RF for AGC would have to happen after the 12mhz crystal
filter.
Not really¡ it can happen anywhere in the chain.? The issue is the
bandwidth of:
? 1) the attenuator and 2) the detector used for the AGC.?
? With the right parts, anything is possible. AGC should detect what's in the passband of the receiver, nothing
more, nothing less. If RF into the AGC detector is wider, then any
QRO signal in the band will quiet the receiver. I can vaguely imagine
ways to make it work with the AGC detector in front of the IF filter,
but they aren't pretty.? ?I'm fine with just detecting the audio on a
$109 transceiver.
Let us know how your AGC scheme works once finished.
Though I'm more in Don's camp, agonizing about whether a $0.50 PIN
diode array is worth the expense when a $0.02 FET is almost good
enough.
On Tue, Mar 27, 2018 at 06:03 pm, K9HZ wrote:
Detecting RF for AGC would have to happen after the 12mhz
crystal
filter.
?
Not really¡ it can happen anywhere in the chain.? The issue is the
bandwidth of: 1) the attenuator and 2) the detector used for the
AGC. With the right parts, anything is possible.
Would be tough to do on a uBitx without having that detector
get
swamped by 12mhz BFO energy given the total lack of shielding.??
?
I would certainly not argue with this¡specially with one that is
wide banded and sensitive.
Nobody has tried.
?
Um¡ no.? I currently am using a AD8367 ultra wide band variable gain
amplifier with a AD8361 true RMS detector fed back to the VGA via
an AD820 high speed Op Amp configured as a combination LP filter
and integrator with a ¡°voltage¡± offset (RF Gain control).? Using a
few components, I¡¯m able adjust the time constants in the
integrator for different AGC reaction speeds (basically a pot for
continuous slow-medium-fast-none).? I think this sort of scheme is
used in some VHF receiver applications.? Not finished yet¡ (not
ready for prime time- looks like a mess), but is very promising as
a true RF AGC that rivals the AGC circuits used in some of the
world¡¯s best receivers. Stand by.
?
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I think you have it backwards.?
No strong adjacent channel signals should be present after the 12mhz filter.
However, they are present prior to the filter.
toggle quoted message
Show quoted text
On Tue, Mar 27, 2018 at 07:14 pm, Tim Gorman wrote:
If you don't detect AGC till after the 12Mhz filter then you risk having
strong adjacent-channel signals controlling the AGC rather than the
signal you are interested in.
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If you don't detect AGC till after the 12Mhz filter then you risk having strong adjacent-channel signals controlling the AGC rather than the signal you are interested in. tim ab0wr On Tue, 27 Mar 2018 20:03:46 -0500 "K9HZ" <bill@...> wrote: Well¡.then again¡.
Detecting RF for AGC would have to happen after the 12mhz crystal
filter.
Not really¡ it can happen anywhere in the chain. The issue is the
bandwidth of: 1) the attenuator and 2) the detector used for the
AGC. With the right parts, anything is possible.
Would be tough to do on a uBitx without having that detector get
swamped by 12mhz BFO energy given the total lack of shielding.
I would certainly not argue with this¡specially with one that is wide
banded and sensitive.
Nobody has tried.
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Re: The issues of the TDA2822
Dear Ash,
My suggestion is to use TBA810,? most common amplifier IC, 4 W output at 12V to 8 ohms speaker.
Assembled ckt board is available at Rs 35 every where.
Regards
VU2JON
JOHN
On Mar 27, 2018 9:10 PM, "Ronald Payne" < wb5klj@...> wrote:
I have just gotten my ubxi40 up and running about a 5 days ago. Has the FCI TDA2822 chip. Running the radio on 13.5V. I did place a 10 ohm resistor in series between the output and the headset/speaker jack, so far no issues.
Ron P.
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>>>Detecting RF for AGC would have to happen after the 12mhz crystal filter.
> Not really¡ it can happen anywhere in the chain.? The issue is the bandwidth of:
>? 1) the attenuator and 2) the detector used for the AGC.?
>? With the right parts, anything is possible.
AGC should detect what's in the passband of the receiver, nothing more, nothing less. If RF into the AGC detector is wider, then any QRO signal in the band will quiet the receiver. I can vaguely imagine ways to make it work with the AGC detector in front of the IF filter, but they aren't pretty.? ?I'm fine with just detecting the audio on a $109 transceiver. Let us know how your AGC scheme works once finished. Though I'm more in Don's camp, agonizing about whether a $0.50 PIN diode array? is worth the expense when a $0.02 FET is almost good enough.
On Tue, Mar 27, 2018 at 06:03 pm, K9HZ wrote:
>>>Detecting RF for AGC would have to happen after the 12mhz crystal filter.
?
Not really¡ it can happen anywhere in the chain.? The issue is the bandwidth of: 1) the attenuator and 2) the detector used for the AGC.? With the right parts, anything is possible.
>>>Would be tough to do on a uBitx without having that detector get swamped by 12mhz BFO energy given the total lack of shielding.??
?
I would certainly not argue with this¡specially with one that is wide banded and sensitive.
>>>Nobody has tried.
?
Um¡ no.? I currently am using a AD8367 ultra wide band variable gain amplifier with a AD8361 true RMS detector fed back to the VGA via an AD820 high speed Op Amp configured as a combination LP filter and integrator with a ¡°voltage¡± offset (RF Gain control).? Using a few components, I¡¯m able adjust the time constants in the integrator for different AGC reaction speeds (basically a pot for continuous slow-medium-fast-none).? I think this sort of scheme is used in some VHF receiver applications.? Not finished yet¡ (not ready for prime time- looks like a mess), but is very promising as a true RF AGC that rivals the AGC circuits used in some of the world¡¯s best receivers. Stand by.
?
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Re: ubitx wavy gravy when copying FT8
On Tue, Mar 27, 2018 at 05:28 pm, Rod Self wrote:
I am seeing some "wavy gravy" audio artifacts
Hi Rod! Funny you mention Wavy Gravy! Ben & Jerry are bringing it back this year! If this is of any help, here's a screen shot of the waterfall from my Bitx-40 also running WSJT-X. No wavy lines, but there is always a vertical line at about 2200. You can also see a?spike there on the spectrum display at the bottom. Don't know what it's from, but it doesn't seem to be bothering anything.  ? -- John - WA2FZW
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Re: ubitx wavy gravy when copying FT8
Have you changed the bfo settings from the factory set ones?
On Wed, 28 Mar 2018, 06:08 Rod Self, < km6sn@...> wrote:
Hi All,
When running WSJTX in FT8 mode on ubitx 40 meters:
I am seeing some "wavy gravy" audio artifacts that do not seem to
be
related to the SI5351 frequency stability. See the attached
waterfall picture ub2cw.png
The "wavy gravy" ("WG" herein) appears not to be the fault of the
SI5351. I say that
because the red line at about 1600 is a stable CW signal I
injected for reference. As
you can see, the CW signal is steady; therefore, the SI5351 is
steady. But the WG is not.
For completeness, I am using KD8CEC 1.04 software, although I do
not believe it is
software related.
It is possible that a harmonic of a signal from the Arduino Nano
is beating with a harmonic of
the steady BFO. However, the WG signal spacing is a mystery.
Has anyone else seen such artifacts on a waterfall?
For reference purposes, attached is a waterfall picture from a
commercial rig, a Yaesu FT-840.
Ideas?
Regards,
Rod KM6SN
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Well¡.then again¡. ? >>>Detecting RF for AGC would have to happen after the 12mhz crystal filter. ? Not really¡ it can happen anywhere in the chain.? The issue is the bandwidth of: 1) the attenuator and 2) the detector used for the AGC.? With the right parts, anything is possible.
>>>Would be tough to do on a uBitx without having that detector get swamped by 12mhz BFO energy given the total lack of shielding.??
? I would certainly not argue with this¡specially with one that is wide banded and sensitive.
>>>Nobody has tried.
? Um¡ no.? I currently am using a AD8367 ultra wide band variable gain amplifier with a AD8361 true RMS detector fed back to the VGA via an AD820 high speed Op Amp configured as a combination LP filter and integrator with a ¡°voltage¡± offset (RF Gain control).? Using a few components, I¡¯m able adjust the time constants in the integrator for different AGC reaction speeds (basically a pot for continuous slow-medium-fast-none).? I think this sort of scheme is used in some VHF receiver applications.? Not finished yet¡ (not ready for prime time- looks like a mess), but is very promising as a true RF AGC that rivals the AGC circuits used in some of the world¡¯s best receivers. Stand by.
? ? Dr. William J. Schmidt - K9HZ J68HZ 8P6HK ZF2HZ PJ4/K9HZ VP5/K9HZ PJ2/K9HZ ? Owner - Operator Big Signal Ranch ¨C K9ZC Staunton, Illinois ? Owner ¨C Operator Villa Grand Piton ¨C J68HZ Soufriere, St. Lucia W.I. Rent it: Like us on Facebook! ? Moderator ¨C North American QRO Yahoo Group. ? email:? bill@... ? ?
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From: [email protected] [mailto:[email protected]] On Behalf Of Jerry Gaffke via Groups.Io
Sent: Tuesday, March 27, 2018 4:02 PM
To: [email protected]
Subject: Re: [BITX20] #bitx40 #ubitx ? Don's solution detects audio, as do all other AGC schemes I've seen implemented in this forum.
Don is attenuating RF though, whereas most schemes here have attenuated audio.
Detecting RF for AGC would have to happen after the 12mhz crystal filter.
Would be tough to do on a uBitx without having that detector get swamped by 12mhz BFO energy
given the total lack of shielding.??
Nobody has tried.
On Tue, Mar 27, 2018 at 01:47 pm, Dexter N Muir wrote: This is NOT Audio - it's IF - an RF AGC. AM superhets rectify the IF and feed the 'average' DC forward to control the RF gain. Here we're talking about boosting the RF / IF to provide that DC (output) to feed forward and control the input. This supposedly means less Audio distortion and greater control range, a more constant 'average' signal level into the 'detector'. AM has its Carrier to determine this 'control voltage'. SSB doesn't, so needs more RF to average.Well, that's my understanding anyway. ?
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Re: Erratic tuning with my new uBitx
Chris
1. This is because the option to show frequency shift in CWL and CWU is checked.?
Until Version 1.04, this Option Check was the default value.
In Version 1.061, the default option is Unchecked, so your problem will be solved.
Or if you want using Version 1.04, uncheck the checkbox next to "Shift Display Frequency on CWL, CWU Mode" in uBITX Manager
It will be displayed as USB or LSB.
However, I recommend updating to Version 1.061.
2.I did not think it was important to show the firmware version, so I just showed up for a second.
Arduino nano has one issue.?It is reset arduino when the serial port is connected.?I have reduced unnecessary time to minimize the reset time of the Arduino Nano that the user feels.
I also turned on uBITX several times to see the version. lol
Let's consider things such as uBITX Manager that can view version information. Thanks for good idea.
Ian KD8CEC
Hi Mike
Thanks, I have Ubitx manager running on my winXP machine now and have successfully made my Callsign change. It would be nice if the Startup Display were to stay on a bit longer though, particularly because it shows the Firmware version - or can the Firmware version be easily displayed once the uBITx is running?
One oddity is that when I enable RIT it displays TX frequency (RIT Tx) incorrectly, although the correct value is used for TX (I am using Mode=CWL and I monitor my TX frequency using an RF sniffer, which has also been confirmed by the RBN). The RIT Tx is always displayed 900Hz high, being 200Hz higher than my RX frequency (ie I am tuned to 700Hz above a contact's carrier to get the readable audio tone). I haven't figured out the logic of the code yet to see how it is happening: at first glance it looks OK, since line 614 of "ubitx_menu" is "ritEnable(frequency)".
So I did an experiment. I changed "ubitx_menu" line 614 to "ritEnable(frequency-900)". Upon restarting the uBITx I found displayed RX and TX frequencies for RIT were what I expected, but the ACTUAL transmit frequency was not, being 900Hz low. When I then disabled RIT the displayed RX frequency had been decreased by 900Hz. I'm not sure what the actual receive frequency was at that point, but clearly that was not a solution to the problem so I changed the code back again!
Incidentally, by swapping the positions of RIT and Band Set in the Main Menu I now find the operating procedure for CW works much better for me. Once tuned into a station I wish to call (ie tuned to give a 700Hz tone), I simply have to double-press the menu button to enable RIT and can immediately make any RX tuning adjustments during the QSO without changing my TX frequency. This has made my CW operation 1000% easier. The only issue is that the incorrect TX frequency is being displayed - I just have to remember it's 900Hz high, but it would be good to get that sorted out!
Does all this make sense to you?
Chris
-- Best 73 KD8CEC / Ph.D ian lee kd8cec@...
(my blog)
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Jerry, I thought I had replied to this but I can't find it anywhere. All you really need is to rectify the audio into a positive DC voltage and then apply that to a PNP transistor. Set the transistor up with your desired idle voltage on the collector, e.g. 2v, 10v, whatever. Then as the rectified positive voltage goes up with stronger signals the collector voltage will go down causing the PIN attenuator to increase its attenuation. The audio voltage will have to get to at least .7v before the diode threshold is reached and a positive voltage generated to the base of the PNP transistor. You can use this to set a threshold using a resistive divider if needed. E.g use an amplifier stage from the output of the audio pre-amp which feeds a potentiometer which can be set to provide the threshold for attenuation to begin. Then each user can set the threshold based on their speaker/headphone requirements. tim ab0wr On Tue, 27 Mar 2018 08:27:13 -0700 "Jerry Gaffke via Groups.Io" <jgaffke@...> wrote: I said "not loud enough" because the PIN diode bridge takes a higher
control voltage to give less attenuation, backwards from the FET
attenuator we usually see in this forum. You decide if it is "not
loud enough" by comparing the DC from the detected audio against some
threshold voltage with an op amp or similar.? Seems like this would
work well enough if you want the audio to always have the pretty much
the same volume at the speaker, though I suppose it would be
preferable to have really loud incoming signals come through a bit
louder at the speaker in a well defined manner. Don's 1n4148
attenuator won't be doing any better in this respect.
Figure 5 of the BAP64Q datasheet shows an input return loss of better
than -10dB across all control voltages of interest when in a 50 ohm
environment So might be good enough for 12mhz.
But you're right, putting near the 45mhz filter would be better.
Jerry
On Tue, Mar 27, 2018 at 07:45 am, Tim Gorman wrote:
How do you decide if the audio is not loud enough? Especially in a
simple receiver like this? AGC usually works just opposite of this.
It is based on audio being too loud.
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ubitx wavy gravy when copying FT8
Hi All,
When running WSJTX in FT8 mode on ubitx 40 meters:
I am seeing some "wavy gravy" audio artifacts that do not seem to
be
related to the SI5351 frequency stability. See the attached
waterfall picture ub2cw.png
The "wavy gravy" ("WG" herein) appears not to be the fault of the
SI5351. I say that
because the red line at about 1600 is a stable CW signal I
injected for reference. As
you can see, the CW signal is steady; therefore, the SI5351 is
steady. But the WG is not.
For completeness, I am using KD8CEC 1.04 software, although I do
not believe it is
software related.
It is possible that a harmonic of a signal from the Arduino Nano
is beating with a harmonic of
the steady BFO. However, the WG signal spacing is a mystery.
Has anyone else seen such artifacts on a waterfall?
For reference purposes, attached is a waterfall picture from a
commercial rig, a Yaesu FT-840.
Ideas?
Regards,
Rod KM6SN
|
Re: Erratic tuning with my new uBitx
Hi Mike
Thanks, I have Ubitx manager running on my winXP machine now and have successfully made my Callsign change. It would be nice if the Startup Display were to stay on a bit longer though, particularly because it shows the Firmware version - or can the Firmware version be easily displayed once the uBITx is running?
One oddity is that when I enable RIT it displays TX frequency (RIT Tx) incorrectly, although the correct value is used for TX (I am using Mode=CWL and I monitor my TX frequency using an RF sniffer, which has also been confirmed by the RBN). The RIT Tx is always displayed 900Hz high, being 200Hz higher than my RX frequency (ie I am tuned to 700Hz above a contact's carrier to get the readable audio tone). I haven't figured out the logic of the code yet to see how it is happening: at first glance it looks OK, since line 614 of "ubitx_menu" is "ritEnable(frequency)".
So I did an experiment. I changed "ubitx_menu" line 614 to "ritEnable(frequency-900)". Upon restarting the uBITx I found displayed RX and TX frequencies for RIT were what I expected, but the ACTUAL transmit frequency was not, being 900Hz low. When I then disabled RIT the displayed RX frequency had been decreased by 900Hz. I'm not sure what the actual receive frequency was at that point, but clearly that was not a solution to the problem so I changed the code back again!
Incidentally, by swapping the positions of RIT and Band Set in the Main Menu I now find the operating procedure for CW works much better for me. Once tuned into a station I wish to call (ie tuned to give a 700Hz tone), I simply have to double-press the menu button to enable RIT and can immediately make any RX tuning adjustments during the QSO without changing my TX frequency. This has made my CW operation 1000% easier. The only issue is that the incorrect TX frequency is being displayed - I just have to remember it's 900Hz high, but it would be good to get that sorted out!
Does all this make sense to you?
Chris
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Re: Ubitx variable RF out?
See:
Dr.?William J. Schmidt - K9HZ J68HZ 8P6HK ZF2HZ PJ4/K9HZ VP5/K9HZ PJ2/K9HZ ? Owner - Operator Big Signal Ranch ¨C K9ZC Staunton, Illinois ? Owner ¨C Operator Villa Grand Piton - J68HZ Soufriere, St. Lucia W.I. Rent it:
email:??bill@... ?
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On Mar 27, 2018, at 3:28 PM, Mike via Groups.Io < mikeymustang2000@...> wrote: Group:
? Is there an easy way to make the RF output variable on a Ubitx?
I now have a LDMOS amp that can only take 3 watts max for 1 KW out.
Thank you!
Mike WA3O
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Re: Bitx20 I have completed the RF section and now doing the current test on transmit and recieve.
#bitx20help
Yes the new BITX 3B. I did find a resistor with the wrong value. Replaced the 47 with the correct value 470 on the exciter board. Now the current is the same on the transmit and receive. 12 millamps. It is supposed to be 30 ma on transmit. The receive voltages on Q1 are correct and the transmit voltage on Q13 are also correct.. It has to be something very simple right in front of me but I cant see it. Its fun though.
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Re: Ubitx variable RF out?
Maybe.
I would definitely use coax I were to try moving RV1 to the front panel.?
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On Tue, Mar 27, 2018 at 01:59 pm, Mike wrote:
Thanks for the response. Can I remove RV1 and just move it to the front panel?
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Don's solution detects audio, as do all other AGC schemes I've seen implemented in this forum.
Don is attenuating RF though, whereas most schemes here have attenuated audio.
Detecting RF for AGC would have to happen after the 12mhz crystal filter.
Would be tough to do on a uBitx without having that detector get swamped by 12mhz BFO energy
given the total lack of shielding.??
Nobody has tried.
toggle quoted message
Show quoted text
On Tue, Mar 27, 2018 at 01:47 pm, Dexter N Muir wrote:
This is NOT Audio - it's IF - an RF AGC. AM superhets rectify the IF and feed the 'average' DC forward to control the RF gain. Here we're talking about boosting the RF / IF to provide that DC (output) to feed forward and control the input. This supposedly means less Audio distortion and greater control range, a more constant 'average' signal level into the 'detector'. AM has its Carrier to determine this 'control voltage'. SSB doesn't, so needs more RF to average.Well, that's my understanding anyway.
?
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Re: Ubitx variable RF out?
Jerry ,
?Thanks for the response. Can I remove RV1 and just move it to the front panel?
Thanks!
Mike WA3O?
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Re: Ubitx variable RF out?
Easiest is to adjust RV1, turning clockwise decreases drive.
If SSB (not CW), could reduce mike gain somehow at Q6.
Could add an attenuator between the uBitx and your big amp.
This might be the best solution as it can make the amp more stable
to be driven from a well behaved 50 ohm source.
?
I'd suggest you make sure your uBitx is clean first.
Spurious outputs that at 10W are barely noticeable will be?
pink ticket bait at 1000W.
Jerry
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On Tue, Mar 27, 2018 at 01:28 pm, Mike wrote:
? Is there an easy way to make the RF output variable on a Ubitx?
I now have a LDMOS amp that can only take 3 watts max for 1 KW out.
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K9HZ
