Re: AE7EU Top Level PCB Mod
Hi Mike,
The mixer is used as an attenuator.? As you bias/turn on the diodes, the more they go into conduction (e.g. not an attenuator).? Balance the circuit, and it becomes an isolator, roughly to the tune of 50dB per the datasheet.? This is why I have a negative gain opamp on the output of the log amp.? As audio level goes up, the output of the log amp goes up.? Invert this, so that maximum audio output = low voltage on the mixer (attenuator), increases attenuation and decreases overall RF reception, and thus the feedback loop.
The attenuator is switched in only on RX; obviously you don't want to TX 10W through this attenuator at any attenuation level.
On Fri, Jan 12, 2018 at 11:37 AM, Mike Woods <mhwoods@...> wrote: Martin
In examining your circuit more carefully, I wonder if you could explain how the AGC works?? The mixer chip appears to be unbalanced by a DC signal from the AGC circuit (derived from the volume control input). However, ?I don¡¯t understand why you are injecting this into the IF output of the transformer and why the input from the antenna is taken to the LO input.? It looks like a design idea that could be used more widely on Bitx designs and won¡¯t require track cutting ...
Mike ZL1AXG So, I've finally got a rough draft of what I'm thinking for my uBitx top PCB mod.? Features at this point are: No modifications required to uBitx board itself (not to say a 470uF anti-pop mod might be bad, or other things couldn't be done) ATU: 7-inductor, 8-capacitor with Hi-Z/Lo-Z switch. Selectable Power output (two power input connectors) Brain transplant:? Teensy3.2 96MHz ARM processor All connections on side edges - no wiring to enclosure Front panel with pushbutton switches DSP Audio (Via Teensy32, would require headphones or amplified speakers) Solderless AGC modification (Attenuator at the front end switched in during RX) Realtime clock (via Teensy32) Linear amplifier control (just a reed relay on a 3.5mm header, sorry, not an RCA, but you could easily change it...) Top side only construction (would make assembly cost lower)
BoM cost:? Probably way higher than it should be.? Needs optimization, and I still need to enter in costs. Complexity:? Probably way more than it should be. Layout:? An ugly mess of routing.? I can't say I like it, but the constraints I put on myself made it really hard to route.? There's lots of open areas to cross with lots of signals going all different directions.
Picture of the layout and schematic PDF attached, along with a 3D view.
I think the one modification that I still need to consider is a microphone preamp.? But, I have no flippin' clue where on the PCB I'd put the gain control knob!? Might have to be an internal potentiometer....
-- Martin Held - AE7EU
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If there aren't any questions, then what is there to learn?
-- Martin Held - AE7EU
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If there aren't any questions, then what is there to learn?
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?Chris -- surely there is SOMEONE not too far from you who can put an update on your firmware.....what state or nation are you in?
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When these boards are done and tested will you be able to buy them all programmed up ready to go for the likes of us who don't have a PC I not in a rush as I am on pre order for my micro bitx like my poor bitx's I have 3 never going to get upgraded
chris
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?lol I had to go back and look what you said since I was offended at all.? Rabbit chases aren't bad if they lead to more ideas.
73, Michael
KM4OLT
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On Fri, Jan 12, 2018 at 12:09 pm, Neil Martinsen-Burrell wrote:
mods
?If you see my reply to Jack as to what got started me on this is a link to what they called SMT Terminals.?? Even without any holes, silk-screening, etc you could attach them to the board for attaching mods. 73, Michael KM4OLT
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?Jack,
?Yeah I'm loving the fact so many people we can learn from as well as share with experiences.
?What got me started on this as a thought was an email I received from All About Circuits and they had an article on
73, Michael
KM4OLT
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Re: Bitx40/Raduino - no power out
As I recall, the Bitx40 is around 150ma in receive. Pressing the PTT button for transmit will bring that up some, your 310ma with zero IRF510 drain current might be fine. You can then either increase RV1 for 410ma, of which the additional 100ma is going from the IRF510 drain to ground. If you were to break away the separate power connector for the IRF510 and put a meter in series with that 12v line, you should see the current go up from 0ma to 100ma.? But probably not necessary to do that. Good that the receiver works, you should be most of the way there. You can reduce the heat on the Raduino's LM7805 by adding a 50 ohm 1/2 watt resistor in series with the 12v lead from the bitx40 to the Raduino.? Adding a cap to ground from each end of the resistor can reduce tuning clicks? if that's a problem, I've heard reports of 1uF to 100uF and more being good. ; None of this addresses your prime issue of why transmit does not work. Most failures on the Bitx40 are in the torroids, check T5,T6,T7,L5,L6 closely with good light and a magnifying glass, look for shorts, no solder, or perhaps an attempt to solder to enameled wire that hasn't had the enamel stripped back.? Use an ohmmeter to nearby pads (not directly on the coil's pads, you are trying to check out the soldering job) to verify that there is zero ohms?through each winding.?? We've had at least one report here of a torroid that failed from shorts within the windings, but that is very unusual, possibly failed when the toroid got hot and the enamel was compromised. Then check DC voltages at each transistor in the transmit chain comparing with Randy's figures: ? ? /g/BITX20/files/K7AGE? If nothing obvious, you need some way to look at AC voltages.?? This can be done with a scope, or with a diode RF probe + dvm. Compare with my figures in post? ? /g/BITX20/message/22764Jerry
On Fri, Jan 12, 2018 at 12:22 pm, Vic WA4THR wrote:
Thanks for the reply, Jerry. I cannot get below 0.31a by adjusting RV1 as measured by a DVM in series with the power supply. As delivered it was drawing 0.40a at about the 10:00 position, but it ceases getting any lower after about the midpoint (12:00) of rotation and at the fully CW end I still read 0.31a off the power supply. In other words, it is never zero, as described in the adjustment procedures, which led to me making the post for help. The check at the CCW end was very brief...less than a second, and immediately turned back. The IRF510 heat sink has never even gotten warm (unlike the voltage regulator sticking out from the Raduino...that thing is hot!). The voltage measured at the IRF510 pins seems OK, but "something" seems to be drawing current all the time. However, the audio I picked up sounds pretty normal...no hum or squeals. Could this be having some sort of high frequency oscillation or something?
Sorry for changing the subject heading from my original post...nobody had answered and it looked like the problem is not just one of setting bias.
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He's been very helpful and has a lot of patience to deal with what he has.?? That's why I wanted to keep it simple.
?In thinking about it.? If nothing else if certain test points can be defined maybe just document where the test points should be.?? Then there is no reason you can't sold the test points at the end of the component without the holes.? I don't know how long the through-hole part of it is.? It may need some clipping to keep them short.? Wouldn't want them to put stress on anything.?? Definitely the last option is my least favorite.?
? 73, Michael
KM4OLT
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Re: CW conditioning adapter pcb
#ubitx
I just ordered one. PC 4 dollars shipping 6 dollars they need to learn how China posts Chris
On 12 Jan 2018 20:17, "KD8CGH" < rkayakr@...> wrote: Cool
I planned to assemble one on a piece of perf board, but this would be cleaner.
??? Bob?? KD8CGH
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When these boards are done and tested will you be able to buy them all programmed up ready to go for the likes of us who don't have a PC I not in a rush as I am on pre order for my micro bitx like my poor bitx's I have 3 never going to get upgraded chris
On 12 Jan 2018 20:15, "Jack Purdum via Groups.Io" <jjpurdum= [email protected]> wrote: Arv:
Agree with all that you said. Obviously, that won't solve all issues but test points and the additional mile that Hans has gone raises the bar for everyone. Our VFT/TFT board for the BITX40 has a number of test points, with holes for pins, silk screened onto the board (e.g., TP2). Alas, I can't tell you how many emails I got saying "Part TP2 marked on the board isn't listed in the BOM". Ya can't win...
You're absolutely spot-on with the comment about running out of I/O pins, which is why our board brings all of the unused Mega 2560 I/O pins out for experimentation. Al Peter, AC8GY, and I are redoing the board for the ?BITX since it has so many features plus the AD9850 II is now stupidly priced. (BTW, this source has them listed for $12.30: .) The new board is going to stick with the Si5351. We are a LONG way off from having anything even ready for testing, but we are watching what's going on with everyone here very closely. We will definitely have more test points on the board (and a note in the manual telling what they are!) and maybe even try for some of the features Hans has added to the bar.
Is this fun stuff or what?
Jack, W8TEE
Michael?? KM4OLT
A possibly better approach seems to be on the horizon from several fledgling ham
radio kit designers.? QRP-Labs has included digital voltmeter capability in the QCX
transceiver that can be configured to monitor strategic points.? Enhancement of that
built-in-test-equipment may be the new future of ham radio kits.? This requires a
significant number of digital and analog inputs to the micro-controller.? This may
force migration to something like the Arduino Mega-2560 board with its 50-plus
inputs and outputs, and a small price increase to support that action.? The larger
processor would also increase amount of memory available for software to support
testing and additional features.
Of course that does not help if the control system is the problem.? For this your idea
of returning to documented test points may be a good idea.? Maybe it would suffice
to silk-screen test points as being connections to specific parts of installed components.
That would point to appropriate places to test without the cost and real-estate
requirement of adding hardware for connection pins and pads.
Arv? K7HKL
_._
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Re: Bitx40/Raduino - no power out
Thanks for the reply, Jerry. I cannot get below 0.31a by adjusting RV1 as measured by a DVM in series with the power supply. As delivered it was drawing 0.40a at about the 10:00 position, but it ceases getting any lower after about the midpoint (12:00) of rotation and at the fully CW end I still read 0.31a off the power supply. In other words, it is never zero, as described in the adjustment procedures, which led to me making the post for help. The check at the CCW end was very brief...less than a second, and immediately turned back. The IRF510 heat sink has never even gotten warm (unlike the voltage regulator sticking out from the Raduino...that thing is hot!). The voltage measured at the IRF510 pins seems OK, but "something" seems to be drawing current all the time. However, the audio I picked up sounds pretty normal...no hum or squeals. Could this be having some sort of high frequency oscillation or something?
Sorry for changing the subject heading from my original post...nobody had answered and it looked like the problem is not just one of setting bias.
=Vic=
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Re: CW conditioning adapter pcb
#ubitx
Cool
I planned to assemble one on a piece of perf board, but this would be cleaner.
??? Bob?? KD8CGH
|
Arv:
Agree with all that you said. Obviously, that won't solve all issues but test points and the additional mile that Hans has gone raises the bar for everyone. Our VFT/TFT board for the BITX40 has a number of test points, with holes for pins, silk screened onto the board (e.g., TP2). Alas, I can't tell you how many emails I got saying "Part TP2 marked on the board isn't listed in the BOM". Ya can't win...
You're absolutely spot-on with the comment about running out of I/O pins, which is why our board brings all of the unused Mega 2560 I/O pins out for experimentation. Al Peter, AC8GY, and I are redoing the board for the ?BITX since it has so many features plus the AD9850 II is now stupidly priced. (BTW, this source has them listed for $12.30: http://www.electrodragon.com/product/ad9850-dds-signal-generator-module/.) The new board is going to stick with the Si5351. We are a LONG way off from having anything even ready for testing, but we are watching what's going on with everyone here very closely. We will definitely have more test points on the board (and a note in the manual telling what they are!) and maybe even try for some of the features Hans has added to the bar.
Is this fun stuff or what?
Jack, W8TEE
From: Arv Evans <arvid.evans@...>
To: [email protected]
Sent: Friday, January 12, 2018 2:10 PM
Subject: Re: [BITX20] PCB Test Points?
Michael?? KM4OLT
A possibly better approach seems to be on the horizon from several fledgling ham
radio kit designers.? QRP-Labs has included digital voltmeter capability in the QCX
transceiver that can be configured to monitor strategic points.? Enhancement of that
built-in-test-equipment may be the new future of ham radio kits.? This requires a
significant number of digital and analog inputs to the micro-controller.? This may
force migration to something like the Arduino Mega-2560 board with its 50-plus
inputs and outputs, and a small price increase to support that action.? The larger
processor would also increase amount of memory available for software to support
testing and additional features.
Of course that does not help if the control system is the problem.? For this your idea
of returning to documented test points may be a good idea.? Maybe it would suffice
to silk-screen test points as being connections to specific parts of installed components.
That would point to appropriate places to test without the cost and real-estate
requirement of adding hardware for connection pins and pads.
Arv? K7HKL
_._
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Yes, everything we know is that they are still accepting orders at the original price. I wouldn't have any concern with getting what I bought if I placed an order on the website now.
-Neil N0FN
On Fri, Jan 12, 2018 at 2:06 PM, Xcott Craver <xcottcraver@...> wrote: Hi,
The site still has a Buy page listing 109 as the price.? Is HFsignals still accepting orders at this price?? I understand everything's on preorder now, but I want to make sure that an order placed today will "go somewhere."
Thanks, Xcott K2CAJ
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On Fri, Jan 12, 2018 at 1:37 PM, Jerry Gaffke via Groups.Io <jgaffke@...> wrote:
|
Hi,
The site still has a Buy page listing 109 as the price.? Is HFsignals still accepting orders at this price?? I understand everything's on preorder now, but I want to make sure that an order placed today will "go somewhere."
Thanks, Xcott K2CAJ
|
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Show quoted text
On Fri, Jan 12, 2018 at 12:37 PM, Jerry Gaffke via Groups.Io <jgaffke@...> wrote: Test points might best be on the backside, plenty of room for silkscreen legends there.
Self test has been suggested in the past:
? ??/g/BITX20/message/21500
Jerry
On Fri, Jan 12, 2018 at 11:09 am, Arv Evans wrote:
Enhancement of that
built-in-test-equipment may be the new future of ham radio kits.
|
Re: AE7EU Top Level PCB Mod
Martin
In examining your circuit more carefully, I wonder if you could explain how the AGC works?? The mixer chip appears to be unbalanced by a DC signal from the AGC circuit (derived from the volume control input). However, ?I don¡¯t understand why you are injecting this into the IF output of the transformer and why the input from the antenna is taken to the LO input.? It looks like a design idea that could be used more widely on Bitx designs and won¡¯t require track cutting ...
Mike ZL1AXG
So, I've finally got a rough draft of what I'm thinking for my uBitx top PCB mod.? Features at this point are: No modifications required to uBitx board itself (not to say a 470uF anti-pop mod might be bad, or other things couldn't be done) ATU: 7-inductor, 8-capacitor with Hi-Z/Lo-Z switch. Selectable Power output (two power input connectors) Brain transplant:? Teensy3.2 96MHz ARM processor All connections on side edges - no wiring to enclosure Front panel with pushbutton switches DSP Audio (Via Teensy32, would require headphones or amplified speakers) Solderless AGC modification (Attenuator at the front end switched in during RX) Realtime clock (via Teensy32) Linear amplifier control (just a reed relay on a 3.5mm header, sorry, not an RCA, but you could easily change it...) Top side only construction (would make assembly cost lower)
BoM cost:? Probably way higher than it should be.? Needs optimization, and I still need to enter in costs. Complexity:? Probably way more than it should be. Layout:? An ugly mess of routing.? I can't say I like it, but the constraints I put on myself made it really hard to route.? There's lots of open areas to cross with lots of signals going all different directions.
Picture of the layout and schematic PDF attached, along with a 3D view.
I think the one modification that I still need to consider is a microphone preamp.? But, I have no flippin' clue where on the PCB I'd put the gain control knob!? Might have to be an internal potentiometer....
-- Martin Held - AE7EU
-------------------------------------------------------------------------------
If there aren't any questions, then what is there to learn?
|
Test points might best be on the backside, plenty of room for silkscreen legends there. Self test has been suggested in the past: ? ?? /g/BITX20/message/21500Jerry
On Fri, Jan 12, 2018 at 11:09 am, Arv Evans wrote:
Enhancement of that
built-in-test-equipment may be the new future of ham radio kits.
|
CW conditioning adapter pcb
#ubitx
QRPGuys is offering a small pcb only that addresses the cw issues with mechanical contacts and the inputs of the uBITx, identified here in the forum . Details can be found at
73,
ken - wa4mnt
www.qrpguys.com
|
Michael?? KM4OLT
A possibly better approach seems to be on the horizon from several fledgling ham
radio kit designers.? QRP-Labs has included digital voltmeter capability in the QCX
transceiver that can be configured to monitor strategic points.? Enhancement of that
built-in-test-equipment may be the new future of ham radio kits.? This requires a
significant number of digital and analog inputs to the micro-controller.? This may
force migration to something like the Arduino Mega-2560 board with its 50-plus
inputs and outputs, and a small price increase to support that action.? The larger
processor would also increase amount of memory available for software to support
testing and additional features.
Of course that does not help if the control system is the problem.? For this your idea
of returning to documented test points may be a good idea.? Maybe it would suffice
to silk-screen test points as being connections to specific parts of installed components.
That would point to appropriate places to test without the cost and real-estate
requirement of adding hardware for connection pins and pads.
Arv? K7HKL
_._
On Fri, Jan 12, 2018 at 10:26 AM, Michael Monteith via Groups.Io <michael_r_monteith@...> wrote: ?? I wonder if extra pads could be added to future boards to install test points?? That might make it easier to have strategic test points to check levels and have a common reference point.? Instead trying to specify which end of a capacitor, coil, etc to test from.?? Then people could install these:
?? If you didn't install the pins at least you have a labeled reference point.? That would help in maybe establishing a stable troubleshooting and testing guide if one gets written.? Having not to manage holding meter leads and scope probes to small components with the chance of slipping would make them valuable too.? It would be nice to clip your scope probes on and have hands free to adjust knobs etc.
?73, Michael
KM4OLT
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Michael Monteith
Vic WA4THR
Bob Benedict, KD8CGH