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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Show quoted text
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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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.??
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Well, I just got my Bitx40 Raduino....Let me build and test that out and I'll get to the uBitx. I want to mate them with a 25W PA I plan to design. Why? Because I want to try to make a broadband PA w/o needing LPFs...
--
AncelB, MIT EE6002
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Re: W8TEE Software Release 1.07-09
Yep. The cost is $8, domestic shipping is included. Use PayPal to econjack@.... Be sure to add your shipping address.
Jack, W8TEE
From: "robert.m.cox@..." <robert.m.cox@...>
To: [email protected]
Sent: Thursday, October 5, 2017 1:14 PM
Subject: Re: [BITX20] W8TEE Software Release 1.07-09
Is it still possible to purchase the TFT/VFO boards for this project??
73,
-Rob
N4MN
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No, Pat. RC is still at FET gate, just FET drain via C to Q1 base. Value of C could alter the severity of the FET's effect, but would still not have much effect on overall action. If connecting C to Q2 or Q3 base likewise, though I'd be cautious of messing up Zout of Xtal filter. I'd be trying around 100pF there, same as the coupling cap.
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Jerry et al: Q1 should be fine, to 'normalise' the chain. 'messing up impedances' will only occur once the FET becomes resistive, i'e. Vg > (turn-on threshold), at which point all that happens is reduced throughput, the original intent - self-normalising. I'd keep it pre-demod - Z there really matters! And strong signals will always cause havoc. If AF detection, they'd need to be reasonably close to tuned-f to do much damage.
PIN diode schemes evidently work best, but this would be far simpler and thus less expensive, plus easier to understand and still with tolerable performance.
73 , Dex
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Here's the thread on distortion: ?? /g/BITX20/message/32043
You need to detect the signal level somewhere after the crystal filter,? since you only want the signal you are receiving to engage the agc action. Top of the volume control pot is probably good enough. Most solutions posted to this forum attenuate after the audio pre-amp at Q16. But as Henning points out in that thread, Q16 is limiting our dynamic range. So the AGC circuit should attenuate the signal before Q16.? Exactly where you should attenuate isn't terribly clear to me. If attenuating at Q1, the noise level when strong signals are present could be louder than it needs to be. Messing with Q1, Q2 and/or Q3 will affect impedances there, which may impact the performance of the BPF, ring mixer, crystal filter, and maybe even the demodulator. I'd probably just use a pin diode attenuator at the output of Q3 as noted in the above thread. Jerry
On Thu, Oct 5, 2017 at 03:47 pm, Dexter N Muir wrote:
For anyone using this scheme: I recall someone encountering distortion due to something in the Rx before this point. I had the thought (that still remains): why not 'feed-forward' like AM AGC? My replacement Raduino is currently en route, and I haven't yet had the chance to try this - has anyone else done so? I envisage detecting the audio level at the top of the Vol pot as this does, but taking the FET drain to Q1 base via 0.1uF and with time constants in between adjustable for fast/slow "hang". What say, folks?
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N8DAH
Ancel