Connect the PA power and trace with multimeter is the 12V is there at
L8, T7 and IRF drain.
If you blew the fuse then you may have blown a PCB track.
Raj, vu2zap
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At 19/03/2017, you wrote: Hi all, although not a new subject, now that there are many more users, I'm hoping to get some direction to fix the problem. My friend had his Bitx working but added a speaker and accidently hit the PA/IRF510 tab to the frame of the speaker. He had added a 2 amp fast acting fuse and it blew. 4-5 fuses later, he realized where the short was but the radio still won't transmit. He replaced the PA, still no luck. If you have any experience in this area of the Bitx, what other component(s) might have been affected by this error? He tried to set bias again but gets no bias current reading. Thanks
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I also shorted my IRF150m to ground and and blew a fuse. After that I had no power out. Following a tip on this board I traced the voltage from PA PWR1 through L8 I found that there was no voltage at T7. The circuit board trace was blown. I wired a jumper from L8 to pin 6 of T7. I then had again had PA voltage at the Drain of the IRF150 and power out on transmit.
/g/BITX20/topic/bitx40_transistor_voltage/4336465?p=,,,20,0,0,0::Relevance,,Voltage+measurements,20,2,0,4336465
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If the display works, it's likely in the Si5351 somehow. ?Replacing just that $1 USD chip would be tough, it has some awfully small pins. ?Best path forward might be to buy an Si5351 board from etherkit.com or adafruit.com, around $10 USD. ?If it arrived non-functional you might try sending an email to hfsignals at gmail dot com, but cost and time to ship both ways makes this hardly worth the bother. ?If you want to sell it, you might name a price.
On Sun, Mar 19, 2017 at 04:07 pm, Brian Lewis wrote: If he can't get it working I'd sell my bitx40 board. My setup came with a bad raduino board and I can't replace just that. ? ?
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Re: Order has not yet arrived
Hi Randy, You can add my order to your list.
Ordered March 8, 2017 and Shipped March 18,2017. Will let you know when it arrives. 73, Kevin NZ1I Mystic, CT
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Re: Letting the smoke out
AAARRRRRGGGHHH! Lost it again. After? reassembling into case I no longer get power out on transmit. Receive works. Voltages on Q15 look correct on receive and transmit. 0.17 A draw on receive jumps to 0.29 on transmit, but no longer goes higher on speaking into mike and 0 RF out on power meter. I have replaced Q15 and no change. The removed Q15 tests OK by the"Quick and Dirty MOSFET Test" method:
https://www.youtube.com/watch?v=RBJGOOTEwfU&t=145s Any suggestions as to what to check next?
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Greetings,
I need to make a parts order for another project I am doing, so I
looked at the uBITX schematics to find some extra parts to pad my
parts order. I have put the parts list I made up on a temporary web
page that will expire on March 30, 2017. I will take the web page down
at that time. However, I thought that perhaps others might be
interested in the parts list I made, so I am making it available. I
know it will be obsolete when Ustād Farhan-ji finishes updating
everything.
uBITX Parts List - Expires 30 March 2017
73 DE KM4NFQ
P.S. If you are reading this post after 30 March 2017, the above link
will not work.
toggle quoted message
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On Sun, Mar 19, 2017 at 6:08 PM, Rafa? Lichwa?a <rafal@...> wrote: Hi Farhan,
I'm really glad to see you are working on the next version of the BITX
project (good job! :-), but please let me ask how the BITX40 works (Dale -
sorry for of topic here).
Could you please tell me how the bi-lateral AMPs work?
Why you think bidirectional RF AMPs has input/output impedance translation
50->220 and 220->50 ohms? (if I understand well for 10 ohms in emitter and
1,1k (double 2,2k in parallel) in feedback)
I've read your project description in the original BITX project, but I'm not
convinced about that.
I've just put this AMP in the simulator (Multisim 11.0) and there is no such
impedance translation...
Regards,
Rafal SP3GO
W dniu 2017-03-19 o 04:00, Ashhar Farhan pisze:
Dale,
I optimised the design further. Reducing the relays to just three. I
added another cyrstal too as it really makes a difference. There should
be a 4.7k resistor in series with the AGC diode too. I will update this
in a few days. It has been hectic around here.
- f
On 19 Mar 2017 1:30 a.m., "dvhammer_99" <DaleHammer@...
<mailto:DaleHammer@...>> wrote:
Farhan,____
Really looking forward to building the uBITX and am in the process
of gathering together all of the components. Also going to go SMD
as you did. I have a few questions from studying your written
description and the picture.____
__ __
1. ?1. The picture appears to show four relays and I only
count three in the schematic.____
2. ?2. The picture appears to show seven crystals in the 12
MHz filter and the schematic shows eight. ____
3. ?3. I can’t figure out the function of the P2 connection
that comes off of the K3 relay, pin 12____
__ __
I know I am probably missing obvious answers but just can’t figure
it out.____
__ __
Planning to use the K7QO “Muppet” pcb technique for construction,
breaking the design into small modules (about 16 in all), and place
them on a 6” x 6” so pcb as you did. Going to go at it slow and
test out each module as much as my knowledge and test equipment will
allow. I have the PHSNA (Poor Ham’s SNA) to check out the filters
and will work on a way to test the amps.____
__ __
Thank you so much for your design !____
__ __
73,____
Dale K9NN____
|
No, you can't...but you can easily build a substitute with all the parts and methods easily available.
And you can build a VFO to handle frequency any time.
john
AD5YE
|
If he can't get it working I'd sell my bitx40 board. My setup came with a bad raduino board and I can't replace just that. ?
|
Hi Farhan,
I'm really glad to see you are working on the next version of the BITX project (good job! :-), but please let me ask how the BITX40 works (Dale - sorry for of topic here).
Could you please tell me how the bi-lateral AMPs work?
Why you think bidirectional RF AMPs has input/output impedance translation 50->220 and 220->50 ohms? (if I understand well for 10 ohms in emitter and 1,1k (double 2,2k in parallel) in feedback)
I've read your project description in the original BITX project, but I'm not convinced about that.
I've just put this AMP in the simulator (Multisim 11.0) and there is no such impedance translation...
Regards,
Rafal SP3GO
W dniu 2017-03-19 o 04:00, Ashhar Farhan pisze:
toggle quoted message
Show quoted text
Dale,
I optimised the design further. Reducing the relays to just three. I
added another cyrstal too as it really makes a difference. There should
be a 4.7k resistor in series with the AGC diode too. I will update this
in a few days. It has been hectic around here.
- f
On 19 Mar 2017 1:30 a.m., "dvhammer_99" <DaleHammer@...
<mailto:DaleHammer@...>> wrote:
Farhan,____
Really looking forward to building the uBITX and am in the process
of gathering together all of the components. Also going to go SMD
as you did. I have a few questions from studying your written
description and the picture.____
__ __
1. ?1. The picture appears to show four relays and I only
count three in the schematic.____
2. ?2. The picture appears to show seven crystals in the 12
MHz filter and the schematic shows eight. ____
3. ?3. I can’t figure out the function of the P2 connection
that comes off of the K3 relay, pin 12____
__ __
I know I am probably missing obvious answers but just can’t figure
it out.____
__ __
Planning to use the K7QO “Muppet” pcb technique for construction,
breaking the design into small modules (about 16 in all), and place
them on a 6” x 6” so pcb as you did. Going to go at it slow and
test out each module as much as my knowledge and test equipment will
allow. I have the PHSNA (Poor Ham’s SNA) to check out the filters
and will work on a way to test the amps.____
__ __
Thank you so much for your design !____
__ __
73,____
Dale K9NN____
|
You need first to measure the voltages on the board. If you get no current gain by adjusting RV1, then probably you have no gate voltage.
Start by connecting your power supply to the board with an ammeter in the line. Is there any current draw at all?
It should be 5v or so at the top of RV1. Do not allow more than 4v on the gate of the IRF510!
Zero volts means a bad 5v VR. But make sure there is input voltage to the VR as well. It is possible
that a trace or two was burnt. Bad regulators or open traces are the two most likely causes
of the problem.
It is also possible that some or all of the other VRs on the board are defective. Check all the voltages
with an input of about 9v. Watch out for shorts! Most of the board will take 9v. Some of it will not.
If all that looks ok, check for cold solder joints. A sudden spike might cause one to show up.
Hope this helps.
john
AD5YE
|
Brian, I reuploaded the Sketch to the BITx40 Radiuno board and replaced the 25mHz crystal and still no workie. ?So that one is going into the junk bin. Wished I could have helped. ?You might contact Farhan and see if you can purchase just the Si5351/Raduino board. ?Let me know if he'll sell just that and I'll purchase one also. Mark W5MCU
|
Hi Peter, Thanks for replay! See my comments inline below... Yes, the lack of matching keeps the circuit simple but you pay the price
of less than the best achievable performance from this circuit. In the
real world you will need to measure and compare the results of both
matched and unmatched circuits to see the performance difference and
keep in mind that often what looks good on paper does not translate into
a large practical (real world) difference, ie; the improvement may not
be worth the added complexity. Sure. I fully agree. Based on my own experiments I can just confirm: theory is sometimes very far from the practice :-) [...] for the DBM to
be effective the diodes need to be switched hard on/off as quickly as
possible. That's right! It seems to me that it is probably easier to achieve this if
the DBM is being driven from a low impedance source which ensures
maximum current flow through the diodes. Hmmm... are you sure? There is no current flowing through the diode until we pass the diode voltage barrier (depending on the type of diode it is usually from 0,2V to 1V). So I think the voltage on the diode is much more important then the current in fast switching conditions. Following your point (but I'm not convinces about that) the mixer should work even better having 200 ohms on each port (in opposition to 50 ohms) because we have higher voltage on the port much earlier for greater impedance. Is my understanding correct? I'm not convinced about that and I think there is really no difference in mixing efficiency when we have any different impedance (on each port!) then 50 ohms. Do you have any materials (I mean experiments, measures etc.) which say that I'm wrong in that? This link was posted by a member of our group in the past and compares
the performance of various DBM's. I was very happy to see that the
homemade 1N4148 DBM's performed so well against the commercial DBM's. Of
course you will have to be careful in how you build the homemade DBM,
match the diodes and be careful with the transformers but if you do a
good job the results can be quite good. See link below:
Thanks for this link! I have to analyze it in details, but a brief look shows that 1N4148 can be really close to ADE-1 if you spend a lot of work on that (diode matching, well positioning etc.) But that means, we can have really good results (or even better) without that pain - just by using ADE-1 single chip - so, less complexity, less pain, more repeatability, right? :-) Regards, Rafal SP3GO
|
Re: Using switching power supply....
Between the power supply and the capacitors that Arv
K7HKL recommends you might also construct a common-mode choke from
a junk box powdered iron toroid you might have (T-37 or T-50
material best) and some #18 insulated copper wire.? Add a couple
47 nF (0.047 MF) capacitors on either side of of the choke.? See this YouTube video.
--Larry
K7LJG
|
Re: Using switching power supply....
Rob? N3DSY
Add a large capacitor (470 to 4700 mfd) across the DC output and any of them
should be acceptable.? Might also add a 0.005 across that larger capacitor to
insure that higher frequency spikes are shunted off to ground.
Arv? K7HKL
_._
On Sun, Mar 19, 2017 at 1:49 PM, <robpnelson@...> wrote: I have a few orphaned laptop power supplies in the junk box- would one of these be 'clean' enough to use for this radio?
--
N3DSY - Rob
|
Re: Using switching power supply....
I have a few orphaned laptop power supplies in the junk box- would one of these be 'clean' enough to use for this radio?
--
N3DSY - Rob
|
Re: Baofeng microphone mod for BITX
I'm curious why you replaced the Microphone's electret 'capsule' with the one provided in the kit?
Aren't these mic's all electret anyway?
I've bought a couple of these on eBay - one for an ACTUAL Beofeng radio and another for ... 'experimentation' just like this, so I appreciate your work! I've found them for as cheap as USD$2.89. Quality: be prepared to repair.
The first one I bought - worked perfectly.
The second - PTT is fine, Speaker fine... No transmit. Solution: solder a little piece tinned buss wire to join the electret in. Bad solder join or bad PCB trace.
Link: https://mikeyancey.com/heres-what-2-89-will-buy/
This is a SUPER idea, BTW. The BitX20 kit I have has a 4-pin (old) Kenwood-style connector, which indeed, will support a Speaker in the Mic. Mike Yancey, KM5Z
Dallas, Texas, USA
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Re: MAR-3SM+ and new display/VFO board coming
Howard:
I wrote the assembly manual for 24 members of my club who have already built the kit. About 5 of those had never built anything before, so I feel that the board and the code are stable. QRPGuys are only selling the board, but they sold out the first shipment of 50 boards in 2 days. They have almost sold out of the second shipment of 50 boards. The PCB board is not really "new", but is the same one that my club members used. It's only "new" in the sense that I've had to reorder the board several times because more people have purchased it than we expected.
I am not selling the board; only QRPGuys are. You would need to order all of the parts for the board yourself. You can read through the list of parts and the assembly manual, as those are free downloads from their site. That should help you decide whether you want to purchase it or not.
73, Jack W8TEE
From: W6IDS <w6ids@...>
To: BITX20@groups.io
Sent: Sunday, March 19, 2017 1:36 PM
Subject: Re: [BITX20] MAR-3SM+ and new display/VFO board coming
Hi Jack,
?
Forgive me, but as a newbe to the group, I’m still playing catch up with
the BITX project and your own MAR-35M
and display board.
?
I did go to the QRPGuys and look at the analyzer information.? I’m now
assuming that? newbe can do the task
of programming because of the stable code.? It would have to be an
error on my part for it not to be done
properly.? I’m speakng to the board assembly as well.
?
Am I to wait for the release of your new PCB and code before
purchasing?? It’s not an actual complete kit
per se, right?? Would the new boards be purchased from QRPGuys?
?
I read where many current boards have been purchased for the
analyzer.? Are people assembling the unit, installing
the code for practice per se?? Then, when your code is released,
remove the analyzer code and install yours
for the digital display?
?
Howard W6IDS
?
Sent: Wednesday, March 15, 2017 11:02 PM
Subject: Re: [BITX20] MAR-3SM+ and new display/VFO board
coming
?
Dennis Kidder (W6DQ and co-author of
the Arduino Projects book) is
the brains behind the changes we're making; I'm just plugging in the code. When
we're done, everything will be put into Open Source and the PCB will be
available, too. Farrukh is redoing the PCB to bring out more of the Arduino Mega
pins to headers to make hacking the system easier. We're working like crazy to
get everything done for the FDIM conference where it will be
presented.
Jack,
W8TEE
?
|
Hi all, although not a new subject, now that there are many more users, I'm hoping to get some direction to fix the problem. My friend had his Bitx working but added a speaker and accidently hit the PA/IRF510 tab to the frame of the speaker. He had added a 2 amp fast acting fuse and it blew. 4-5 fuses later, he realized where the short was but the radio still won't transmit. He replaced the PA, still no luck. If you have any experience in this area of the Bitx, what other component(s) might have been affected by this error? He tried to set bias again but gets no bias current reading. Thanks
|
Re: MAR-3SM+ and new display/VFO board coming
Hi Jack,
?
Forgive me, but as a newbe to the group, I’m still playing catch up with
the BITX project and your own MAR-35M
and display board.
?
I did go to the QRPGuys and look at the analyzer information.? I’m now
assuming that? newbe can do the task
of programming because of the stable code.? It would have to be an
error on my part for it not to be done
properly.? I’m speakng to the board assembly as well.
?
Am I to wait for the release of your new PCB and code before
purchasing?? It’s not an actual complete kit
per se, right?? Would the new boards be purchased from QRPGuys?
?
I read where many current boards have been purchased for the
analyzer.? Are people assembling the unit, installing
the code for practice per se?? Then, when your code is released,
remove the analyzer code and install yours
for the digital display?
toggle quoted message
Show quoted text
From: Jack Purdum via Groups.Io
Sent: Wednesday, March 15, 2017 11:02 PM
To: BITX20@groups.io
Subject: Re: [BITX20] MAR-3SM+ and new display/VFO board
coming
?
Dennis Kidder (W6DQ and co-author of
the Arduino Projects book) is
the brains behind the changes we're making; I'm just plugging in the code. When
we're done, everything will be put into Open Source and the PCB will be
available, too. Farrukh is redoing the PCB to bring out more of the Arduino Mega
pins to headers to make hacking the system easier. We're working like crazy to
get everything done for the FDIM conference where it will be
presented.
Jack,
W8TEE
?
|
Re: QRP Labs Low Pass Filters
I forgot to say that, if anyone is wondering if they have similar issues a quick check is to measure the input SWR with the filter terminated in 50 Ohms. Simulation (and measurement) shows that the SWR will have risen to about2.7:1 at the -1dB point and to 5.7:1 at the -3dB point.
Steve G3TXQ
|
Raj vu2zap
Bob Benedict, KD8CGH
Kevin Gilot NZ1I