No audio from last week may have a solution
So last week I said that there was an audio hiss, but no signal on my UBitx v4. I think I may have traced the problem. The capacitor C4 seems to have been mechanically scraped off the board. My surface mounting skills are not up to much. Am I best trying to bridge it with a conventional 100 nf capacitor, try to get some surface mount or get a replacement board.
What are the vendor like at sending out replacement boards? Any idea how much the board would be?
Best wishes
Sean 2e0sfq
Sent from my Huawei Mobile
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Re: Reasonable cost Spectrum Analyzer for Ham use.
#ubitx
Possibly for some less expensive alternatives can see this message chain
https://www.eham.net/ehamforum/smf/index.php/topic,123052.0.html
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oh, and it's a 4 transistor AGC board
...that I'm looking for instructions/diagram on installing.
Looks like there's at least a couple versions.
Thanks John K5MO
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VA3NOI/ND6T AGC board received. Box folder found, now.... for installation?
I've got my uBitx apart and have just received a ND6T agc board throughole with the VA3NOI board layout I think. I have all the parts to populate this, but are there instructions as to how to install it in my uBitx?
Thanks! I look forward to not being blasted out of the headphones soon :-)
John K5MO
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Re: Reasonable cost Spectrum Analyzer for Ham use.
#ubitx
Hi,
I've been following these replies with interest. Lots of practical information on what the trade-offs are vs cost of the rf-explorer vs a full spectrum analyzer. Particularly the signal levels to avoid self generated spurs and the resulting rise in measurement noise floor, and workaround manual measurements. (If I have time to continue with my homemade SDR SA, I imagine the overload vs noise floor levels will be a significant issue, also). One person reminded me of the value of a tracking generator for testing and adjusting filter designs.?
It looks like the rf-explorer may be better than my homage SDR SA project; at a reasonable cost. Comparing those choices, the rf-explorer seems to be the best choice. After, the dust settles on some of my client projects I can decide if I can justify the cost of a real SA for some future projects. Temped to go ahead and get the rf-explorer in the meantime. ?
Tom,
wb6b
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Re: RF Preamp - Attenuator
Hi do you have the files for the RF pre-am and the agc?
Hard to see the pic there do the files specify exactly where the connections go to the main board?
Thanks
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Tried that it's hard to actually even record my volume is so soft to start out with.? But from what I can tell it's seems to be tuned about correct.
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Sorry. typo in the prior email:
Once the BFO is aligned, then can go back to the main VFO calibration, though I believe that if you truly zero beat the signal, adjusting the BFO should NOT impact the calibartation.??
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There is a free program for Windows (link attached), that is an audio spectrum analyzer using a mic input.? Process is to tune to an open channel and? view the spectrum.? The spectrum should go from around 500 to 2500, or there approximately.? ?Then use the CEC Memory Manager to adjust the BFO until the noise is centered and about 2.5khz in width.? Seemed to really help with the audio quality of my receiver.
Link to program:
Web Page: I got this technique from a post in BITX20, though no longer have the link.
What you are doing is aligning the BFO with the crystal filter so that the signal is not attenuated by the filter skirts.
Once the BFO is aligned, then can go back to the main VFO calibration, though I believe that if you truly zero beat the signal, adjusting the BFO should impact the calibartation.
I used this method after setting up the recommended way, and noticed a significant improvement in audio quality and reduction in noise.
73 Evan AC9TU
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Receive frequency seems perfect though so if I change it that would impact my receive frequency also right?? BFO sounds spot on for the receive.
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Sounds like you BFO is off.
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All, Please ignore my previous email.? I did not realize it was a Bitx40 rig.? I do not have any experience with that board.
Next time I should read the header BEFORE I respond.
Sorry. Evan AC9TU
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Christopher,
Off chance, have you checked the output of the 5vdc regulator on the Raduino board?? If the regulator is toast, then you could be wiping out the nanos on over voltage (an known issue for the nano).
The one on my rig got quite warm, so I added a heatsink and put a 4 ohm 5 watt resistor on the input to the regulator.? If you do not have plans to power more from the 5vdc supply (like the Nextion screen and stand alone spectrum analyzer from CEC), or plan on running the rig (the radio side, not the Power Amp, that can be independent) at greater than 12vdc, then you can increase the value.? The Raduino clone board from Jim Sheldon (a good board and kit in my opinion) uses a 47 ohm resistor.? For a 12v source, that would limit the current that can be supplied to the 5v devices to 128ma before the input voltage drops below specified minimum, more than enough for a standard rig, a little short if running a large display and another nano.? The available current of course increases if the supplied voltage goes to 13.5 - 160ma approximately. This is driven by the minimum input voltage to the 7805 regulator.
Minimum mod required for the regulator circuit is to add a heatsink to the 7805 regulator.
Above are my observations/opinions/calculations.? I could be wrong, so would suggest that you verify, and if anyone else on the thread has different information that they provide it please.
73 Evan AC9TU
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It may also be a bootloader issue.
Recent Nano's?come with?a newer bootloader:
73 Allard PE1NWL
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Re: Help to enable S-meter in KD8CEC v 1.071
Pete,
Andy is correct, you need a more recent version of the KD8CEC software as the S-meter appeared in version 1.08 of his releases.
73, John (VK2ETA)
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Now, that brings up another idea. Some of the computer/laptop
power supplies have a 12V line and also a 18/19V line. But it
the two power lines are separated and the radio used the 12V
line, the amp line could use the higher voltage as suggested
by the designer Ashhar Farhan, VU2ESE, and could deliver
more power oout. Some printer power supplies have this
voltage output. I am not sure they are adequately regulated
or noise free enough to use here and are showing up in stores
like Goodwill or are available where printers are replaced with
new one when they are offering new printers and cartridges
for as little as $29.95 and some buy them to get the cartridges.
Some voltages are 35V, also. Laptop supplies are often running
at 18V, the one mine uses is set at 18V.
May not work but it is an idea that bears checking out.
Bob ¡ª KK5R
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On Sun, 12/16/18, Gordon Gibby <ggibby@...> wrote: Subject: Re: [BITX20] bitx40 displays version, hums, but does not receive #bitx40help #bitx40 #radiuno To: " [email protected]" < [email protected]> Date: Sunday, December 16, 2018, 11:51 PM Laptop switching power supplies are cheap, often available in thrift stores for pennies on the dollar, and can power the PA section. 19 V is common.? ?A cheap switch mode 12 V wall wart can handle the rest.? A seven, eight, or 9 Ahr gell cell is also pretty cheap. $22 at Walmart in the hunting section, as people use them to power deer feeders. ?I have used one pretty successfully with a uBitx, re-charging it with a battery maintainer. ?Just don¡¯t discharge them below 11.9 V or so On Dec 16, 2018, at 23:40, Jerry Gaffke via Groups.Io <jgaffke@...> wrote: As Bob suggests, a simple old school wallwart consisting of a transformer and a rectifier is generally not suitable for powering electronics such as an amateur transceiver. The open circuit voltage will be considerably higher than the voltage under load. And there will be a problem with hum. Even a modern switch mode wall wart of good design probably won't have sufficient power for a uBitx (though a desktop brick style supply might work fine, it can be bigger). But there are good wall warts out there with good voltage regulation and very little noise, well suited for low power electronics such as a radio receiver. ? Jerry, KE7ER On Sun, Dec 16, 2018 at 06:56 PM, Bob Lunsford wrote: In other words, a simple wall wart device delivers that voltage at that current but if the load is decreased, the voltage climbs and could be much hither than the device needing a power supply can survive. Ideally, all our electronic devices will avoid wall warts and a fully regulated power supply, voltage-wise, should be a minimum requirement. Using a wall wart for anything is inviting a castrophe.
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Re: Reasonable cost Spectrum Analyzer for Ham use.
#ubitx
I agree with the other posters that it's a useful instrument, if
you know its limitations.
Using the RF Explorer, I was able to confirm that replacing the
relays on my ubitx rev 4 board cleaned up all harmonics in CW mode
to better than -48 dBc on all bands.? Prior to the relay fix, my
worst case was -29 dBc for the 3rd harmonic on 30m.CW.
Some limitations to watch for:
- The specified max input power and DC level limits are
unusually low, so I use a DC block with plenty of attenuation to
protect the instrument.? The User Manual even warns about front
end damage with an unterminated but otherwise unconnected input.
- Horrible internally-generated (inside the RF Explorer) spurs
appear whenever the input signal is somewhat above approx. -50
dBm on the direct input mode.? For ubitx work @ 10W output, I
use 70 dB attenuation: a 30 dB 25 Watt attenuator + 20 dB
Mini-Circuits attenuator + 30 dB internal attenuator. This keeps
the display clean of RF Explorer spurs, but limits my effective
dynamic range to about 50 dBc on a 3 MHz span.?
- If I try to look at all harmonics at the same time, for
example, 6-40 MHz spam for a 40m signal, signals at the -43 dBc
FCC limit are below the noise floor.? I have to look at one
harmonic frequency at a time with a narrower span.? I've thought
about automating this tedious process with Python.? There is no
way to independently set the resolution bandwidth to a small
value on a wide sweep.
- The min frequency step size is 1 kHz and the minimum
resolution bandwidth seems to be 2 kHz.? This limits the RF
Explorer to looking at widely separated spurs and harmonics and
effectively sets the noise floor.? I don't expect it to be
useful for resolving intermodulation products on a two-tone
test.
- The minimum span in kHz is equal to the number of FFT points
selected in the settings (options are 112, 511, 1023, etc.)
Carlos
KJ6ST
On 12/16/2018 12:09, Tom, wb6b wrote:
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Hi,
I've been busy with client projects as of late. Looks like most of
the uBitx issues will be solved by the time I get back to playing
with it. That is good.
I ran across this fairly low cost spectrum analyzer?.
Anyone with any experience or ideas on how viable this spectrum
analyzer would be for Ham use? It has been around long enough that
I wonder if there are other similar analyzers that may exist now.?
Even if all the uBitx issues get resolved, it has illustrated how
valuable a spectrum analyzer can be to the Ham's measurement
tools. I think it would be great to add a spectrum analyzer to my
test equipment for future projects and experimenting. I might
cough up the $1K+ for one, but rather have one that cost less if
it can do most things a Ham would be interested in.?
Tom,
wb6b
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Laptop switching power supplies are cheap, often available in thrift stores for pennies on the dollar, and can power the PA section. 19 V is common.? ?A cheap switch mode 12 V wall wart can handle the rest.?
A seven, eight, or 9 Ahr gell cell is also pretty cheap. $22 at Walmart in the hunting section, as people use them to power deer feeders. ?I have used one pretty successfully with a uBitx, re-charging it with a battery maintainer. ?Just don¡¯t discharge
them below 11.9 V or so
On Dec 16, 2018, at 23:40, Jerry Gaffke via Groups.Io < jgaffke@...> wrote:
toggle quoted message
Show quoted text
As Bob suggests, a simple old school wallwart consisting of a transformer and a rectifier
is generally not suitable for powering electronics such as an amateur transceiver.
The open circuit voltage will be considerably higher than the voltage under load.
And there will be a problem with hum.
Even a modern switch mode wall wart of good design probably won't have sufficient
power for a uBitx (though a desktop brick style supply might work fine, it can be bigger).
But there are good wall warts out there with good voltage regulation and very little noise,
well suited for low power electronics such as a radio receiver.
?
Jerry, KE7ER
On Sun, Dec 16, 2018 at 06:56 PM, Bob Lunsford wrote:
In other words, a simple wall wart device delivers that voltage at that current
but if the load is decreased, the voltage climbs and could be much hither
than the device needing a power supply can survive.
Ideally, all our electronic devices will avoid wall warts and a fully regulated
power supply, voltage-wise, should be a minimum requirement. Using a
wall wart for anything is inviting a castrophe.
|
As Bob suggests, a simple old school wallwart consisting of a transformer and a rectifier
is generally not suitable for powering electronics such as an amateur transceiver.
The open circuit voltage will be considerably higher than the voltage under load.
And there will be a problem with hum.
Even a modern switch mode wall wart of good design probably won't have sufficient
power for a uBitx (though a desktop brick style supply might work fine, it can be bigger).
But there are good wall warts out there with good voltage regulation and very little noise,
well suited for low power electronics such as a radio receiver.
?
Jerry, KE7ER
toggle quoted message
Show quoted text
On Sun, Dec 16, 2018 at 06:56 PM, Bob Lunsford wrote:
In other words, a simple wall wart device delivers that voltage at that current
but if the load is decreased, the voltage climbs and could be much hither
than the device needing a power supply can survive.
Ideally, all our electronic devices will avoid wall warts and a fully regulated
power supply, voltage-wise, should be a minimum requirement. Using a
wall wart for anything is inviting a castrophe.
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One comment in this user's comment makes me remember something
that no doubt others know but it may still be useful for someone who
has not heard it before.
Some people pick up a wall wart and see something like 12V 2A printed
on and think this is suitable for general use. Unless it's a newer version
of the device that is not depending on a transformer and rectifier to give
the 12V 2A and is of solid state design where the voltage is pretty much
on target for the 12V, an old transformer type with rectifier will deliver the
12V at 2A but if you hook it up to a device only pulling a fraction of that
current, 1/2-A for example, the voltage may be up to something like 18V.
In other words, a simple wall wart device delivers that voltage at that current
but if the load is decreased, the voltage climbs and could be much hither
than the device needing a power supply can survive.
Ideally, all our electronic devices will avoid wall warts and a fully regulated
power supply, voltage-wise, should be a minimum requirement. Using a
wall wart for anything is inviting a castrophe.
By the way, built my UBITX and love it. Still have to get a microphone
because I think I got the eletret element too hot. But as a receiver, I am
fully satisfied. Reminds me a little of the IC-718 as regards the menus but
the UBITX is much, much simpler and no menu list need be carried to the
field when using it.
Bob ¡ª KK5R
nocrud222 at yh dot com
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On Sun, 12/16/18, Christopher M. Hobbs <cmhobbs@...> wrote: Subject: Re: [BITX20] bitx40 displays version, hums, but does not receive #bitx40help #bitx40 #radiuno To: [email protected] Date: Sunday, December 16, 2018, 8:13 PM When I connect a serial monitor to the arduino, I don't get any data out of it.?? I've also tried to hook the arduino back up to my computer to burn the new v1.28.1 code to it and I have the exact same problem I had with the previous arduino that shipped with the kit (that formerly worked) when I try to upload the sketch: avrdude: stk500_recv(): programmer is not responding avrdude: stk500_getsync() attempt 1 of 10: not in sync: resp=0x00 avrdude: stk500_recv(): programmer is not responding ... avrdude: stk500_getsync() attempt 10 of 10: not in sync: resp=0x00 Problem uploading to board.? See for suggestions. This was happening when I realized the last board was toast and I fear this one is as well.? It is *not* a connection issue between my computer and the board.? I successfully programmed this board twice before.? My guess is last time I hooked the radio up, when I thought the board was dead, it was a matter of adjusting the contrast.? I bet the last board was stuck displaying the Raduino version as well as it's making the same humming noise it made previously when the other board failed. At this point I think that something must be shorted somewhere or maybe my power isn't clean.? This new board is exhibiting the same behaviour as the other board when it failed.? I'll shelve the project for now.? I'm not sure i have the patience or equipment to figure out what's killing these arduinos. Thanks to all for your help! 73 DE KD5RYO
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Allard PE1NWL
Bob Lunsford