Re: Many uBitx's have reduced power on 40m CW
On Sun, Apr 11, 2021 at 10:49 AM, Jerry Gaffke wrote:
Would be useful to know a bit more about how you conducted the IMD test:
? What tones were injected into the mike jack, and at what level.
700 and 1900 hertz were injected into the mic jack.? I had adjusted the level for the maximum power without causing an increase in the IMD3 measurement.
? Exactly which unwanted product was observed when measuring IMD
I measured the expected 2xfa +/- fb.? 4 values that were all fairly equal.
? Signal level observed into Q90.
I did not probe with the scope.
? Power out to the dummy load.
Power out varied from 10 on 80meters to 2 on 10meters
Just figures for 40m would be most helpful.
Will do it later this week. 73 Evan AC9TU
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Re: Linear Amplifier Build
Jerry, KF6VB,
There might well be better forums to complain that 100W is not enough.? ;-)
I'd take another look at that antenna.
Should be a bunch more sunspots coming along soon.
Let me know when the XYL finally convinces you to put that 30L-1 out on the sidewalk.
If it's in the bedroom now, I'm guessing sooner rather than later.
Jerry, KE7ER
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Re: SI labs generator chip which has an FM input pin
Why not use phase modulation instead pure FM? The receiver doesn't know the difference and a simple phase modulator stage could be fitted after the clock output, I recall using a germanium transistor and later a FET and coupling the signal from drain and source, balancing it and then unbalancing the whole circuit by having a capacitance diode in one leg that was modulated by the audio. That was in late 60's. early 70s, and my recollection to the details might suffer a little. I bet the circuit can be found and adopted from old books.
John
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All,
I know this isn't the right forum for this - anybody know of
a forum for people building linear amps?
Last night, I had my first contact in some years. A pleasant gentleman in Calgary. Unfortunately, he could not hear me as well as
I heard him, and we had to cut it short. So frustrating! I was reminded of why we have linear amps. I was running barefoot, 100W.
So this morning, I hauled the 30L-1 out of the shed. Oh my aching back! The 30L-1 is a 60's vintage Collins linear with 4 811-A tubes.
It's big. It's heavy. It does Not Belong in this bedroom.
I'm looking forward to building the LDMOS amp that I ordered on Ebay.
Also looking forward to the uBITX transceiver.
For me, ham radio is about two things - building equipment, and chatting about building equipment :).
- Jerry KF6VB
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On 2021-04-11 07:50, Evan Hand wrote: Jerry,
I did do the testing of my modified v4 against my unmodified v5. I
have posted the power levels of the v4 on this thread. The IMD
measurements that I got are as follows:
Modified v4:
80meters: -21db
40meters: -19db
20meters: -20db
Unmodified v5:
80meters: -22db
40meters: -21db
20meters: -19db
As far as I can tell there is not really much difference in the SSB
performance with the change of C81 to 2670pF.
The only comment that I would make is that overall the IMD3
performance is not what I would like. Another 5 to 6 dB would have
been better.
Harmonics were down 51db for both rigs. I did not test for the spur
on the v4.
Harmonic tests were done with a TinySA connected through a homebrew
50db tap and a step attenuator.
IMD3 tests were done with an RSP1A and the RSP-Spectrum Analyzer
program using the same connections.
At this point, I do not plan to modify my v6 as CW is not a mode I
use. Also, I have other rigs that excel at QRP CW that I would use
instead. So my conclusion is to make the mod IF you want the CW
capability. It does not make sense if you are using SSB.
73
Evan
AC9TU
Links:
------
[1] /g/BITX20/message/87545
[2] /mt/81780486/243852
[3] /g/BITX20/post
[4] /g/BITX20/editsub/243852
[5] /g/BITX20/leave/10189903/243852/952924773/xyzzy
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Re: Many uBitx's have reduced power on 40m CW
Evan,
That all looks good, thanks for doing such a thorough analysis!
IMD could vary wildly depending on mike gain, and RV1 setting.
Also, various builds may have significantly different gains due to differences in filters and transistors.
Would be useful to know a bit more about how you conducted the IMD test:
? What tones were injected into the mike jack, and at what level.
? Exactly which unwanted product was observed when measuring IMD
? Signal level observed into Q90.
? Power out to the dummy load.
Just figures for 40m would be most helpful.
I doubt this signal is any wider than an AM phone station,
and should thus be quite acceptable at these power levels.
Of course, creating nearby hash in low power digital mode watering holes could be of concern.
IMD is of even more concern if the uBitx is used with a high powered linear.
Jerry, KE7ER
On Sun, Apr 11, 2021 at 07:50 AM, Evan Hand wrote:
I did do the testing of my modified v4 against my unmodified v5.? I have posted the power levels of the v4 on this thread.? The IMD measurements that I got are as follows:
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Re: Many uBitx's have reduced power on 40m CW
Jerry,
I did do the testing of my modified v4 against my unmodified v5.? I have posted the power levels of the v4 on this thread.? The IMD measurements that I got are as follows:
Modified v4:
80meters: -21db
40meters: -19db
20meters: -20db
Unmodified v5:
80meters: -22db
40meters: -21db
20meters: -19db
As far as I can tell there is not really much difference in the SSB performance with the change of C81 to 2670pF.
The only comment that I would make is that overall the IMD3 performance is not what I would like.? Another 5 to 6 dB would have been better.??
Harmonics were down 51db for both rigs.? I did not test for the spur on the v4.
Harmonic tests were done with a TinySA connected through a homebrew 50db tap and a step attenuator.
IMD3 tests were done with an RSP1A and the RSP-Spectrum Analyzer program using the same connections.
At this point, I do not plan to modify my v6 as CW is not a mode I use.? Also, I have other rigs that excel at QRP CW that I would use instead.? So my conclusion is to make the mod IF you want the CW capability.? It does not make sense if you are using SSB.
73
Evan
AC9TU
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Re: Farhan to give sBITX talk at FDIM
I am looking forward to this talk.? I have at least one ?BITX that I plan to convert.
73
Evan
AC9TU
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Re: Farhan to give sBITX talk at FDIM
I am really looking forward to this talk. It is the summary of almost a year's experiments in SDR starting from zero. I also describe how to convert a standard issue ubitx into an?sdr using a raspberry pi. - f
On Sun, Apr 11, 2021 at 5:29 PM Bob Benedict, KD8CGH < rkayakr@...> wrote:
note this talk "Ashhar Farhan VU2ESE - sBITX - An Open Source SDR that YOU can hack!"
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? 73
??? Bob? KD8CGH
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farhan@...> wrote:
My embarrassment would be the relay-based computer science fair
project that I tried to design in 6th grade. It did work to some
extent until the actual fair. By then the relays were intermittent
and timing between them made it unreliable I know now why relays
can not be used for fast calculations.
*** In a former life, I was responsible for repair & maintenance of something called the "Omni 2000". It was an elaborate rack wiring tester. Given a prewired equipment rack, this thing would test it to see that everything was connected to what it was supposed to be connected to, AND that nothing was connected to anything it was NOT supposed to be connected to. This thing had 7000 reed relays. Almost every day, I would have to replace one or more of them. Generally, one would be stuck closed. But opens were common also. I still remember the sound of the Omni's self test. Those relays would whizz in a musical crescendo. It was a union shop. By investing in elaborate test jigs like the Omni, the company was able to use "testers" instead of "technicians" to do the testing. Testers didn't make as much $$ as technicians. The lady who ran the Omni would always say "But Jerry, it worked just this morning!". My answer: "Hazel, everything works until it stops working" :). - Jerry KF6VB
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Farhan to give sBITX talk at FDIM
note this talk "Ashhar Farhan VU2ESE - sBITX - An Open Source SDR that YOU can hack!"
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? 73
??? Bob? KD8CGH
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The smart, handsome, modest author of that BOM would like to point out that it is for V1.02, not V1.01, so not ideal for Justin. There is a V1.01 BOM here /g/ucx/files/uSDX.xlsxAnd, although the BOM Robert mentioned is a true work of literary art and useful for DigiKey ordering, there is actually a much nicer interactive one for doing a V1.02 build here /g/ucx/files/Bare%20Essentials%20for%20version%201.02%20BuildFirmware, 3D printed case designs and other useful things are in the ucx groups.io files section. -- ? 73 ??? Bob? KD8CGH
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Well that explains things. I didn¡¯t realise that they had it that bad. Over there. Just goes to show you how different the world is these days. I guess I¡¯ll wait awhile. Poor guy.
73,
Robert, AG6LK
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Justin, I found the website where I saw the uSDX BOM for Digikey. Here¡¯s the URL:? /g/ucx/files/WB2CBA%20uSDX%20PCB%20V1.02%20Digi-Key%20BOM Just click on the URL when you get to the website you¡¯ll see an odd file extension but you¡¯ll be able to view it and download it. I hope this helps you. 73, Robert, AG6LK?
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Re: SI labs generator chip which has an FM input pin
One could also get FM by doing it like many old FM mobiles did, by having a separate FM oscillator that was then mixed up with the LO to the TX frequency. In Mobira RC25 this was a 10.7MHz crystal vxo FM modulated with a varactor and doubled to 21.4MHz, the same as the RX IF, before my?s xing with the LO and entering the TX chain. This was done due to the low tuning range of the synthethizer, typically only 1.4MHz.
So doing the 21.4MHz RX/TX difference with a single synthethizer was not possible. Ditto 4.6MHz commercial repeater split, for that a 13MHz modulator crystal was used. As when that got doubled to 26MHz the synth's tuning range was enough and being different from the IF, made fullduplex more possible.
I have also seen folks use a varactor to FM the reference crystal to a synth. But I wonder about the temperature stability of such builds.?
-Ismo, de OH2FTG
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I got delivery from there this week. Ordered March 26.
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On Apr 10, 2021, at 9:22 PM, Jerry Gaffke via groups.io <jgaffke@...> wrote:
?Not sure where Sunil is, but a good bet he's somewhere near Mumbai. ? ?? Give it time, this should sort out eventually. The can use your business. Jerry, KE7ER On Sat, Apr 10, 2021 at 06:31 PM, Robert AG6LK wrote:
Hello everybody,
Does anyone know if, I think their name is, Inkits is open, ( their URL is amateurradiokits.in ). I ordered a uBitx 5¡± Nextion universal case, with all the goodies included, from them two days ago. I went back to their website and there is a small banner across the top that say their closed do to an emergency until further notice. I may have missed this the other day when I ordered. I also noticed below it says, ¡°IMPORTANT NOTICE: STORE IS OPEN.¡±. I have emailed them them twice with email address¡¯s I found on the Internet without a response yet. I don¡¯t know if they¡¯re open or closed. Has anyone ordered from them? I hope I still get my order, even if I have to wait awhile. If anyone has any information I would appreciate it.
73,
Robert, AG6LK?
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Not sure where Sunil is, but a good bet he's somewhere near Mumbai.
? ??
Give it time, this should sort out eventually.
The can use your business.
Jerry, KE7ER
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On Sat, Apr 10, 2021 at 06:31 PM, Robert AG6LK wrote:
Hello everybody,
Does anyone know if, I think their name is, Inkits is open, ( their URL is amateurradiokits.in ). I ordered a uBitx 5¡± Nextion universal case, with all the goodies included, from them two days ago. I went back to their website and there is a small banner across the top that say their closed do to an emergency until further notice. I may have missed this the other day when I ordered. I also noticed below it says, ¡°IMPORTANT NOTICE: STORE IS OPEN.¡±. I have emailed them them twice with email address¡¯s I found on the Internet without a response yet. I don¡¯t know if they¡¯re open or closed. Has anyone ordered from them? I hope I still get my order, even if I have to wait awhile. If anyone has any information I would appreciate it.
73,
Robert, AG6LK?
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Hello everybody,
Does anyone know if, I think their name is, Inkits is open, ( their URL is amateurradiokits.in ). I ordered a uBitx 5¡± Nextion universal case, with all the goodies included, from them two days ago. I went back to their website and there is a small banner across the top that say their closed do to an emergency until further notice. I may have missed this the other day when I ordered. I also noticed below it says, ¡°IMPORTANT NOTICE: STORE IS OPEN.¡±. I have emailed them them twice with email address¡¯s I found on the Internet without a response yet. I don¡¯t know if they¡¯re open or closed. Has anyone ordered from them? I hope I still get my order, even if I have to wait awhile. If anyone has any information I would appreciate it.
73,
Robert, AG6LK?
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Bob,
I'm interested in building the uSDX. What is the cost for the boards & shipping?
I'm interested in the 10 watt build as well.
I'm in zip code 44124.
Dave KE8PXV
Sent from ProtonMail mobile
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-------- Original Message -------- On Apr 10, 2021, 3:41 PM, Bob Benedict, KD8CGH < rkayakr@...> wrote:
I have the V1.02 boards with the plug in band modules.
Later versions had 3 switched bands and he also released serial resonance band boards and a 10 watt amp.
Best start for Barb track is
from there you can go to different versions and add ons like 10 watt amp.
I have a few extra V1.02 boards and band boards if anyone is interested.
--
? 73
??? Bob? KD8CGH
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I have the V1.02 boards with the plug in band modules.
Later versions had 3 switched bands and he also released serial resonance band boards and a 10 watt amp.
Best start for Barb track is
from there you can go to different versions and add ons like 10 watt amp.
I have a few extra V1.02 boards and band boards if anyone is interested.
--
? 73
??? Bob? KD8CGH
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Robert,
I ordered boards using the V1.01 files which were the latest on the antrek site, it appears there some mods that need to be made to the board - boards are done and shipped.? As far as the parts list goes, I found one but need to look up every part and order.? Would be nice if there was a DigiKey BOM...
73,
Justin B.
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Bob Benedict, KD8CGH
Ismo V??n?nen OH2FTG