Re: Changing out L5 & L7 in UBitX for Spur Fix
I ordered the kit from the ubitx.net link on spectral purity:?
I am assuming that it will include the correct devices.
Thank-you for your checking!
73
Evan
AC9TU
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Re: Changing out L5 & L7 in UBitX for Spur Fix
I hope you ordered the right ones like in the pic!
They are shielded and have a resistance of 2 ohms. TDK-EPCOS type is what I used
and also some marked S+M !
Raj
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At 25-12-18, you wrote: Raj,
Thank-you for clearing that up for me. I plan on making the modifications you recommend as soon as the parts come.
Happy Holidays to you and yours.
Evan
AC9TU
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Check voltages in audio stage and vogad when the audio is gone. That
should tell you
where to look!
At 25-12-18, you wrote:
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12vdc from the battery, but
after a resistor and the 7805 is 5vdc.
Il 25/dic/2018 11:37, "Raj vu2zap"
<
rajendrakumargg@...> ha scritto:
- What is the supply voltage for the VOGAD board ?
- At 25-12-18, you wrote:
- >Hi all, I have tested a mic compressor based on the VOGAD SL6270C
(same schematics of its datasheet), and it works very well on the ILER
QRPs. However when connected to the ubitx something weird happens. It
works the first time I push to talk, I can talk also 5 minutes, and no
problem, BUT when I release the PTT and then press again, it does not
transmit anything. I did not remove R60 and put an electrolytic cap (the
positive towards the ubitx) in the cable connecting the VOGAD and the
ubitx. The VOGAD is always powered on via a battery or the same power
supply and is DC isolated from the Ubitx. In fact the interconnecting
cable also has an isolating transformer to avoid any possible ground
loop. Should I really remove R60? Should I remove the DC power of the
VOGAD each time I receive? Or should I simply add some polyester caps in
parallel at the mic input?
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Re: Changing out L5 & L7 in UBitX for Spur Fix
Raj,
Thank-you for clearing that up for me.? I plan on making the modifications you recommend as soon as the parts come.
Happy Holidays to you and yours.
Evan
AC9TU
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12vdc from the battery, but after a resistor and the 7805 is 5vdc.
Il 25/dic/2018 11:37, "Raj vu2zap" < rajendrakumargg@...> ha scritto: What is the supply voltage for the VOGAD board ?
At 25-12-18, you wrote:
>Hi all, I have tested a mic compressor based on the VOGAD SL6270C (same schematics of its datasheet), and it works very well on the ILER QRPs. However when connected to the ubitx something weird happens. It works the first time I push to talk, I can talk also 5 minutes, and no problem, BUT when I release the PTT and then press again, it does not transmit anything. I did not remove R60 and put an electrolytic cap (the positive towards the ubitx) in the cable connecting the VOGAD and the ubitx. The VOGAD is always powered on via a battery or the same power supply and is DC isolated from the Ubitx. In fact the interconnecting cable also has an isolating transformer to avoid any possible ground loop. Should I really remove R60? Should I remove the DC power of the VOGAD each time I receive? Or should I simply add some polyester caps in parallel at the mic input?
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What is the supply voltage for the VOGAD board ?
toggle quoted message
Show quoted text
At 25-12-18, you wrote: Hi all, I have tested a mic compressor based on the VOGAD SL6270C (same schematics of its datasheet), and it works very well on the ILER QRPs. However when connected to the ubitx something weird happens. It works the first time I push to talk, I can talk also 5 minutes, and no problem, BUT when I release the PTT and then press again, it does not transmit anything. I did not remove R60 and put an electrolytic cap (the positive towards the ubitx) in the cable connecting the VOGAD and the ubitx. The VOGAD is always powered on via a battery or the same power supply and is DC isolated from the Ubitx. In fact the interconnecting cable also has an isolating transformer to avoid any possible ground loop. Should I really remove R60? Should I remove the DC power of the VOGAD each time I receive? Or should I simply add some polyester caps in parallel at the mic input?
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Hi all, I have tested a mic compressor based on the VOGAD SL6270C (same schematics of its datasheet), and it works very well on the ILER QRPs. However when connected to the ubitx something weird happens. It works the first time I push to talk, I can talk also 5 minutes, and no problem, BUT when I release the PTT and then press again, it does not transmit anything. I did not remove R60 and put an electrolytic cap (the positive towards the ubitx) in the cable connecting the VOGAD and the ubitx. The VOGAD is always powered on via a battery or the same power supply and is DC isolated from the Ubitx. In fact the interconnecting cable also has an isolating transformer to avoid any possible ground loop. Should I really remove R60? Should I remove the DC power of the VOGAD each time I receive? Or should I simply add some polyester caps in parallel at the mic input?
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Re: Changing out L5 & L7 in UBitX for Spur Fix
Evan,
The caps are only DC blocking and do not have an effect on the filter. I mounted the coils where
convenient. I scraped off the green pcb coating and soldered.
You can also mount them exactly in the place of the old coils but you will need a lead extension
at one end for the SMD coil.
This prevents the harmonics from getting back into the BiDi amp and causing spurs. Its behaviour is
identical to Farhans. Both clean up the higher bands. For lower bands change THREE relays to AXICOM.
Raj
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At 25-12-18, you wrote: Yes, they (C215 and C211) are still installed, however look close at C211 in the picture The left side of the cap was connected to L7. It is now not connected to anything. That is not the case for C215, it is still in series with the filter.
The question was not if it worked or not, I am taking the feedback from ubitx.net that it does. My prior email was more a question for my understanding rather than clarification on how to do it.
73
Evan
AC9TU
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Chris, There is code in the uBitx software, both from the original and KD8CEC code.? I found the following:
//original code with modified by kd8cec
? if (usbCarrier > 12010000l || usbCarrier < 11990000l)
? ? usbCarrier = 11997000l;
?
? if (cwmCarrier > 12010000l || cwmCarrier < 11990000l)
? ? cwmCarrier = 11997000l;
My suggestion is to find these lines in the ubitx_20.ino source file and modify to allow for the range that your rig will need. (note, you will need to download the entire ubitx-1.1.zip from KD8CEC repository)? You can find a link to the files on the Hamskey.com web page.? Also on Github:??in the??(zip) folder
Hope that helps
73
Evan
AC9TU
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Re: Tracing receive signal for low signal
The LPF is designed (we hope) to match the 50 ohm impedance of the antenna...The output (L4/C204) needs to be matched to the input of T2 ...Optimally thats 50 ohms ..connecting your SG across it adds another (maybe) 50 ohms ...not so much matched anymore .. Short of disconnecting the output at TP1 and connecting to a 50 ohm pad to force a 50 ohm termination then sweeping (armstrong style ie manually varying) the frequency of the Signal Gen while watching the scope ...OR Tracking Generator/Spectrum Analyzer? ..OR wideband noise source/spectrum analyzer ..OR comb generator/spectrum analyzer...OR
Some kind of Variable Frequency Source and Some Kind of Wide-band Measureing device ...All of which need to be/have some defined termination resistance/impedance ....
Easiest to fix the audio then start on the known unknowns ..before getting to the unknown unknowns
Whats the scope /bandwidth ? dual trace ? Signal Generator ??? VOM/VTVM/DVM ?
Jim
On Monday, December 24, 2018, 7:58:07 PM PST, Dave Space <davesspacebar@...> wrote:
I will give that a try thanks.
Nice idea you had on the potentiometer.?
I did try something else.? Putting in 1900uv at the antenna gave .1v p-p? where 1900uv at tp1 only gave only about 33mv p-p
I jumpered the inductors L1-L4 and the same 1900uv gave about 75mv p-p.
So seems like the low pass filter might be problematic?
But with the jumper in place I tried to listen to strong signals on the air with and without the jumper and I didn't notice a difference.
(Maybe need the Q70 transistor 11k resistor also.. or there are several problems here that need correcting one at a time I guess.)
I guess I have to order some parts :)? I wonder what could be the problem with the low pass filter.? You seem to have some great idea's on how to check components.? Any good suggested ways to test that filter?? (Try to find the the 3db corner/ bandwidth using the signal generator and oscilloscope perhaps for the filter?)
Dave
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You're welcomed;? My first run with this (lower output audio than happy with, sans shouting) involved the pre-amp that was built into Midland land mobile radios back in the 1980's.? Having worked for ("as") an installer years ago, I found an organ donor in the pile and inserted that circuit into the uBitx. It worked fine and definitely ramped up the audio, though, for pocket change and three weeks shipping from the orient, I had 3 of these boards for playing with.? One had the magic smoke leak out (see "isolate original mike wire to board output") and the other 2 were used as previously posted.
The result has been similar or better audio gain, but with much wider forgiveness at the voice end of the mike. Whether I hold the mike 6" away or under my nose, I get full meter deflection on the antenna tuner's wattmeter, with my added output trimmer set maybe 70% of range (YMMV)..?
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Re: Tracing receive signal for low signal
I will give that a try thanks.
Nice idea you had on the potentiometer.?
I did try something else.? Putting in 1900uv at the antenna gave .1v p-p? where 1900uv at tp1 only gave only about 33mv p-p
I jumpered the inductors L1-L4 and the same 1900uv gave about 75mv p-p.
So seems like the low pass filter might be problematic?
But with the jumper in place I tried to listen to strong signals on the air with and without the jumper and I didn't notice a difference.
(Maybe need the Q70 transistor 11k resistor also.. or there are several problems here that need correcting one at a time I guess.)
I guess I have to order some parts :)? I wonder what could be the problem with the low pass filter.? You seem to have some great idea's on how to check components.? Any good suggested ways to test that filter?? (Try to find the the 3db corner/ bandwidth using the signal generator and oscilloscope perhaps for the filter?)
Dave
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Correct for Nextion display width & fill 2.8" screen
Hi, all.
At the risk of seeming OCD, my current firmware and Nextion 2.8" display goes maybe 80% across the screen, I'm sure that I am seeing all of the firmware "screen" that I should see, but it doesn't fill the physical screen in doing so. Using KD8CEC version 1.1 firmware, UBITX_CEC_V1.100_NX_S.hex.
It's OK and useable as it appears of course (the yellow arrow in attachment below, +/-) which is to say it shows everything the firmware ought to show on the screen.? It would be just that much more cool to use the full width that the screen's capable of (red arrow in attachment, +/-) and might also give my fat fingers a hair more room over which to stab at the control options!
Thanks in advance for your insight.
?
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For mike gain, add an to the mic circuit. Think of this as more along the lines of audio compression than as gain per se.? You will want to put a small elecrolytic cap between this board's output and the mic wire from the mainboard, as that line has voltage on it that this add-on board may not appreciate.? This board has exciter voltage on it's microphone input (since it comes with eletret element itself, that you will remove) so that your line from the hand mic can go right to it.
I chose to include a 50K trim pot soldered right to this board for level control. It makes a hell of a difference in a good way, from signal reports. It takes me from being in the noise, to at least readable copy or from readable copy to "I can't believe you're only running ten watts!".
Give it a try.? I also use one of these boards on the speaker line just before the volume pot. With three selectable gain levels, you can choose how much "help" you want for either application.
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Re: Tracing receive signal for low signal
There ya go ....Transistor is good, elsewise changing the bias would do nothing ..likely the "hum" is being generated because the fool thing is actually amplifying ...Not gonna cost anything extra at this point to put 11k resistor in there and see what happens ..
Jim
On Monday, December 24, 2018, 6:03:53 PM PST, Dave Space <davesspacebar@...> wrote:
With a potentiometer base Q70 to ground I could get 6 volts with it.? It picked up a hum though when I did that.. maybe due to the potentiometer and long alligator clip jumpers I was using.? So that might mean the transistor is good?? Mine needed 11.18k tp get tp 6 volts.
I tried also testing with a low signal not connected to the ubitx just generated nearby and it didn't seem to amplify it at all by holding the potentionmeter base to ground just had that additional hum.
So sounds like I could add a resistor to stabilize if that doesn't add the hum perhaps.
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Re: Tracing receive signal for low signal
Do confirm all is okay from audio output back to the xtal filter output.
At the input side of the xtal filter, proper bfo adjustment is essential so that the carrier falls into the narrow passband.
As these boards are auto assembled,? and tested,? I tend to think that alignment and testing could be the challenge. I don't think we experienced any defects in the 23 ubitx boards in our group build.
73 curt
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Re: Tracing receive signal for low signal
With a potentiometer base Q70 to ground I could get 6 volts with it.? It picked up a hum though when I did that.. maybe due to the potentiometer and long alligator clip jumpers I was using.? So that might mean the transistor is good?? Mine needed 11.18k tp get tp 6 volts.
I tried also testing with a low signal not connected to the ubitx just generated nearby and it didn't seem to amplify it at all by holding the potentionmeter base to ground just had that additional hum.
So sounds like I could add a resistor to stabilize if that doesn't add the hum perhaps.
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Hello everybody,
I build the UBITX by scratch. The second IF is 11.979300 Mhz because of the crystals in the ladder filter. In Arduino I use the kd8cec software v1.1 with nextion display. In the ubitx manager I can upload and save the lower BFO frequency, but after rebooting the BFO frequency is always at 11.997 Mhz. I've found that the lowest storable BFO frequency is 11.990 Mhz. Values below that are saved in the config but are not accepted after a restart. With the Drehcoder I can adjust the lower BFO frequency and also on the SI5351 measure but? after reboot Clk01 has always the default value from 11,997 Mhz. Do i something wrong or is it a problem of the software?
73 de Chris DF1EA!
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Re: Changing out L5 & L7 in UBitX for Spur Fix
We've got a bunch of different spurs. For example, the 12mhz spur due to clk0 crosstalk into clk2 is not going to be cured by swapping out L5,L7. Also, I would not expect that swapping out L5,L7 would clean up a 45mhz-DialFreq spur due to a second harmonic at Q20,21,22.? My best guess had been that L5,L7 prevent energy from the power amp from finding a path back into the 45mhz IF amp and taking another trip through the D1,D2 mixer creating all sorts of unexpected spurs. Perhaps Raj's L5,L7 mod reduces magnetic field coupling from toroids in the PA? Can be problematic to have a 10W amp operating unshielded in the same box with the low level signals going through the IF amps. In post 61645, Farhan states:? "With the relays that are now used for ubitx,? the harmonics at 3.5, 7 and 10 are in under -45 dbc. we don't need the axicom relays." In post 62307, he says: "The boards continued to ship with the same relays as some have also reported no difference with the new relay.? On the other hand, a new board layout with spur fix, allions suggested lpf layout and an lm386 af amp is in the mail. I will prototype it as soon as it arrives and share the results"
My reading is that the v4 uBitx now ships the same as it always has.? ?There have been many many reports here of trouble with harmonics on v4 boards, though perhaps not at the frequencies Farhan was testing at (not 14mhz and up?), and perhaps with toroids oriented a bit differently or something.? So I'd take that "don't need the axicom relays" with a very large grain of salt.? The good news is that post 62307 also suggests that v5 is being actively worked on to reduce spurs and harmonics.
> I have read that Raj has agreed that either the LCL filter OR his replacement of L5 and L7 do reduce the spurs.
I think Raj said his extra 45mhz crystal filter was as good as some of the other fixes, not so sure he has recently claimed the L5,L7 fix to be a cure-all.
Would be good if Raj and/or Farhan could give us an update on the current thinking of all these various spur fixes.
My take:
The extra 45mhz crystal filter might well take care of most of these spurs, though hard to obtain those 45mhz filters, and hard to verify that the center freq of the new one matches the one at Y1.? If adding a 45mhz crystal filter,? I'd want to sweep the IF to verify all is well.
Farhan's LPF filter for the 90mhz harmonic takes care of the 45mhz-DialFreq spur, but won't touch all the lower frequency stuff we get from coupling between PA and IF.
The L5,L7 fix would take care of that coupling, but not the 45mhz-DialFreq spur.
The 12mhz trap fixes a spur that none of the above address.
I don't have a way to easily measure harmonics and spurs? But I'd guess the best path for most is:
? replace kt1, kt2, kt3 with the axicom relays (or add a set of outboard low pass filters)
? do Raj's mod of replacing L5,L7 with shielded 1210 surface mount inductors (other SM inductors did not work)
? do Farhan's LPF mod to knock out that 90mhz harmonic of 45mhz going into D1,D2
? somehow knock down the 12mhz spur due to clk0-to-clk2 crosstalk, perhaps using Farhan's 12mhz trap
This stuff is not trivial to get right.
Would be good to arrive at and easy and simple recipe to clean up the v3 and v4 rigs.
In many cases the spurs and harmonics may not meet regs, but if operating at 5 or 10 watts are not too big an issue.?
Operating the uBitx with a 100W amp could indeed be a big issue, and may attract unwanted attention.
Jerry
On Mon, Dec 24, 2018 at 11:20 AM, Evan Hand wrote:
I have been following all of the threads you have listed above.? Note that the low pass filter by Ashhar is the newest.? I have read that Raj has agreed that either the LCL filter OR his replacement of L5 and L7 do reduce the spurs.? The solution from Ashhar is more complex, in that there are bias resistors that need to be replaced as well.
Ashhar stated in the 61645 thread that the "relays as supplied now" do not need to be replaced.? It is not clear if that means that there are new parts being installed in the current shipping product, or if the originals are OK from v4 boards.? I have been looking for someone to receive a v5 board in the hopes that all of the corrections needed are on that board and we can lay to rest the correct solution to use to solve the spurs and harmonics.
In the meantime I am off the air until I do something.? That may be wait for the QSX from QRPGuys if it becomes available before a v5 board from HF Signals.
73
Evan
AC9TU
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Re: Tracing receive signal for low signal
No sweat ..Thats how I checked mine ..With that miserable "floating bias CR#P" on that circuit, the beta of the transistor determines the operating point ...varying beta will give varying static/no signal collector voltage ...I stabilized that circuit by connecting a 15 K ohm resistor base to ground ...not sure what an in circuit transistor tester would tell ..you could use a 50K pot lashed base to ground , then crank it around until collector voltage is "about" 6 volts ...that would tell you if the Q70 is bad/and what the necessary resistance base to ground to stabilize that circuit Serendipitous Solstice also, too
Jim
On Monday, December 24, 2018, 1:29:05 PM PST, Dave Space <davesspacebar@...> wrote:
Thanks for taking the time to look into it.? I measured the transistors with no signal going through at all.
Hmm.. So you are thinking that all the biasing/feedback resistors are all correct but the transistor itself is bad resulting in the lower voltage?
Interesting I'll probe around there a bit more.? I might have one or two 2n3904 transistors around.? I may actually have a transistor tester around as well.
Thanks!? Hope you have a nice holiday.
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Raj vu2zap
Ted
DF1EA