Ashhar,
Are you going to publish the updated schematic? I have started buying parts to the uBITX, but I have not bought all of them. It would be easy for me to change to a different schematic. Unfortunately I am a electronics technician and not an engineer so it is hard for me to redesign the circuits. But I want to build a uBITX for portable us with a laptop for PSK31. Thank you for sharing your designs.
Art
KB8HGW
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Hi again. I'm having a blast with this radio. I don't know if I'll ever get the case on it, because there are so many improvements to make. Thank you for all the AGC info.
It seems as one question gets answered, another one comes up.
Why can I hear myself talking for a second or so after I press the PTT? I can explain the lm386 action, as the power supply filter cap needs to discharge, however it looks like the audio path should be disconnected by K2 when you go to TX. Also, I found that in order to get the anti chunk 2n7000 circuit to work properly on my rig, I needed to put a .01 mfd capacitor between the volume control wiper and ground. That being said, the fet circuit is currently connected to the rig with foot long clip cords, so maybe some stray pickup?
Thanks again
Brent
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Here us the link to the download page of Sunil's AGC. There is lots of information in the download, I just don't know what to do with it. ?
Then select agc
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Thanks for the info. Yes, i noticed the 2 filters interact. I built a tiny breadboard to plug the relays and filters. Tried various things, even built some other filters and still get the swr issue..
I have an ant analyzer and it shows the filter bw etc - seem ok....
Must play around some more....
Joe VE1BWV
On Fri, Oct 6, 2017 at 11:35 AM, Mike via Groups.Io <mikeymustang2000@...> wrote: Joe,
I can't remember but on the low pass I THINK I had to remove a turn to move frequency up. I may have done it to the band pass also. On my rig band pass adjusment effects low pass. Aso my filters work better connected ?close to the board. I am working on remote switching via the qrp-labs relay boards but the tuning changes slightly .?
Hope this helps!
Mike WA3O?
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Joe,
I can't remember but on the low pass I THINK I had to remove a turn to move frequency up. I may have done it to the band pass also. On my rig band pass adjusment effects low pass. Aso my filters work better connected ?close to the board. I am working on remote switching via the qrp-labs relay boards but the tuning changes slightly .?
Hope this helps!
Mike WA3O?
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Re: Amplified Microphone and the BITX40
It¡¯s very unlikely you¡¯ll damage any component in the radio. Mic levels, even line levels, aren¡¯t so high that the input components on the radio wouldn¡¯t be able to handle it.?
I¡¯m assuming ¡°amplified¡± doesn¡¯t mean ¡°for speakers.¡± If it does, that¡¯s a very different thing.?
So I say give it a try and see!
Having said that, if your mic is amplifying an electret, then it almost certainly will distort because the BitX takes electret level audio natively. If you really want to use THAT MIC specifically (it has EQ? Good form factor? It just looks cool?), you could pad down the output back to electret level (undoing to amplification) and that would probably work. Though it¡¯ll be higher noise just because of the additional amplification stage.
-Mark
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On Oct 6, 2017, at 5:14 AM, N8DAH < Dherron@...> wrote: I would suggest yes on the block cap. spike the power at 5-6w's adjusting the gain in the radio.
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Good morning, I was wondering if you might share your build info.? ?I modified my bitx40 v3 for 20 meters. Used a qrp labs bpf filter and tried several lpf? . The rx works fine on 20meters, but the TX shows very high SWR .
I built other filters? both bpf and lpf with the same results.
Its interesting that your getting the same issues I have except mine is on 20 meters...
Any guidance would be much appreciated
Joe VE1BWV
On Fri, Oct 6, 2017 at 8:21 AM, Mike via Groups.Io <mikeymustang2000@...> wrote: Group,
I have modified ?my Bitx40 to do multiple bands 80-20 but I am struggling trying to get the low pass filter working correctly for 160. The RX seems to work but when I TX I get a high SWR into a known good antenna. I am using the QRP LABS filters. other bands work well. Has anyone been successful with 160 meters and if so what where the steps taken to accomplish it?
Thank you!
Mike WA3O?
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Re: Amplified Microphone and the BITX40
I would suggest yes on the block cap. spike the power at 5-6w's adjusting the gain in the radio.
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On Thu, Oct 5, 2017 at 10:08 pm, Mvs Sarma wrote:
In the pjhotoabove , i suggest the regulator be mounted physically on the marked location in the attachment, and wires extended to the PCB.
Like they say "If it ain't broke, don't fix it!" Mine isn't?getting all that hot, so I'm not going to worry about it. My box does have a fan also, BTW. ? -- John - WA2FZW
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Group,
I have modified ?my Bitx40 to do multiple bands 80-20 but I am struggling trying to get the low pass filter working correctly for 160. The RX seems to work but when I TX I get a high SWR into a known good antenna. I am using the QRP LABS filters. other bands work well. Has anyone been successful with 160 meters and if so what where the steps taken to accomplish it?
Thank you!
Mike WA3O?
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Don't know about using caps instead of the transformers. You'll notice
that the center taps are used making them step ups and step downs. The
ones I got didn't have center taps and the levels were/are fine. I also
didn't have an 820K resistor so I used something else, probably 1 meg.
Vince.
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That is nice, and so simple, I think I could do that one too, Vince. I'm
wondering if a person could change the transformers to 10uf caps like the
duinovox has. I may need to try it just for fun. The duinovox will stay in
my rig. It is working really well with 10 watts. I imagine, if a person
were smart, they could find some uses for those extra pins and memory on
the second nano in the radio.
--
Michigan VHF Corp.
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I'm impressed . Will wait for Your next publications . 73!
On Thu, Oct 5, 2017 at 23:31, Jean-Matthieu F5RCT via Groups.Io <f5rct.jm@...> wrote: Hello All,
Let me introduce me a little. (sorry if I'm writing faults in English, no so easy using a French corrector !)
I'm 49 years old . Electronic engineer in radiocommunication and power conversion. Amateur radio since 1990.
I'm buiding a lot of my equipmenst, last big project was a high level 2m SSB transceiver. I did a 80 m CW transceiver working from 3V to 6V (1W to 4 W).
I plan to build an kind of ubitx using the Raduino (thanks to Farhan's work !).
The difficuly will be to supply the transceiver with a 5 V USB power pack !
Of course transmit power will be limited to 1 W (linear) to 2 W at compression (the output stage of the MOSEF PA is allready working !)
Now I'm facing to the diver of the PA..no easy to ensure flat response at low voltage.
To developp at 50 Ohms is more easy to qualify each sub-circuit : simulating, testing, assembling...
I confirm the fact of using a 45 MHz Xtal filter to avoid looping back (I had this problem on a HP 8590 spectrum close to an internal IF )
It is important to load mixers at 50 Ohms on each port, or dissipate unwated products in a waste load.
LPF front of 1st mixer is very important to avoid image of FM broadcast band if you hare close to big transmitter (that's my case)!
I will continue this project as soon as I will have time ...not in stress !
Best 73 F5RCT Jmat ( ..shorter than Jean-Matthieu !)
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Comparatively, the 7805 is like a dropping resistor. You're taking 12 -14 volts and regulating it to 5 volts. That's a 7 volt drop, which at 1 amp would be:
(InputVoltage - OutputVoltage)* Current Supplied = (12-5) * 1 = 7W
If you compare that to a resistor, you can see that a LDO is not very efficient when compared to a switching regulator. If you use a switching regulator, there are problems associated with RFI to deal with.
Use a heat sink or bolt it to a metal chassis.
On Friday, October 6, 2017 12:03 AM, Paul Avona via Groups.Io <avonap@...> wrote:
The STM voltage regulator on the Raduino board gets really hot. Is that normal?
also, it sticks out and i¡¯d Like to bend it back so my display panel fits in my box. No issue bending it (carefully), right?
thx
paul
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In the pjhotoabove , i suggest the regulator be mounted physically on the marked location in the attachment, and wires extended to the PCB.
?It helps.
On Fri, Oct 6, 2017 at 10:20 AM, John P <j.m.price@...> wrote: On Thu, Oct 5, 2017 at 09:03 pm, Paul Avona wrote:
The STM voltage regulator on the Raduino board gets really hot. Is that normal?
also, it sticks out and i¡¯d Like to bend it back so my display panel fits in my box. No issue bending it (carefully), right?
thx
paul
As I recall, I removed mine, turned it around, then laid it down flat. Here's a picture:
?
--
John - WA2FZW
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On Thu, Oct 5, 2017 at 09:03 pm, Paul Avona wrote:
The STM voltage regulator on the Raduino board gets really hot. Is that normal?
also, it sticks out and i¡¯d Like to bend it back so my display panel fits in my box. No issue bending it (carefully), right?
thx
paul
As I recall, I removed mine, turned it around, then laid it down flat. Here's a picture:  ? -- John - WA2FZW
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Why not add a heat sink if not already done?
?Secondly you mught fix the regulator on the metal enclosure body, if you used one.and extend wires to the raduino pcb. ?I dont recollect whetyher the backlit isat 5V? !!? I generally separate it out and connect to 12V with 1 watt higher value resistor like 560 ohms. Tothat extent, the load is reduced on the regulator. all the best ?sarma ?vu3zmv
On Fri, Oct 6, 2017 at 9:33 AM, Paul Avona via Groups.Io <avonap@...> wrote: The STM voltage regulator on the Raduino board gets really hot. Is that normal?
also, it sticks out and i¡¯d Like to bend it back so my display panel fits in my box. No issue bending it (carefully), right?
thx
paul
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The STM voltage regulator on the Raduino board gets really hot. Is that normal?
also, it sticks out and i¡¯d Like to bend it back so my display panel fits in my box. No issue bending it (carefully), right?
thx
paul
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Again sorry, but Link please? We don't all have a n archive? that comprehensive, and Group's search is pants.
73, Dex
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BITX QSO Night, Sunday, October 8, 7pm Local Time, 7277 kHz in North America, 7177 kHz elsewhere
Join us as we make contacts from BITX40 to BITX40 on 7.277 MHz in 40 meters!
This is a worldwide event for BITX40 stations starting at 7pm in each time zone. To participate, call CQ BITX on Sunday, starting at 7pm your local time. The BITX QSO Night continues through the evening and conditions usually improve after sunset, so it is worthwhile to participate later in the evening.
Suggested Best Operating Practices:
Work at QRP power levels unless conditions require more power.
Call and listen for CQ BITX on the hour and every quarter hour.
It is helpful if you call CQ BITX with your callsign, name and location.?
Repeat your callsign a number of times during your CQ BITX and during QSO's.
Start a QSO by confirming the callsign, location, name and signal report of the other operator.
Say the callsign, name and location of the other operator so others can hear.
If the frequency is busy, avoid long conversations.
After your initial QSO is complete, ask if there are any other stations who would like to contact.
Report your QSO's, discuss propagation, noise, signal reports, audio reports, antenna type, etc. in this thread.
This is an undirected, scheduled event.? The BITX QSO Night relies on you to call CQ BITX to initiate contacts with other stations, so warm up that final and transmit a few calls on Sunday evening.? Talk to you then!
--
John - WA2FZW
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Could Sunil's agc be used? I think it is inserted somewhere in the IF??? I've downloaded the docs on it, but I'm not smart enough to understand all I see. I have the VU2ESE AGC, and I can't tell a big difference, but it does seem to mellow the audio. I like how it sounds, but you still need to ride the volume control.
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Arthur Bryant
Brent Seres/ VE3CUS
Smitty, N6MTS
N8DAH
