Re: UbitX no RF out SSB and CW
Jerry, thanks for the response! I have an Icom 740, which is unable to tune to 11.997 HMz, but I am able to pick up the CW tone transmitted from the ubitx when tuned to the same frequency. Good news! In addition, I am able to receive with the ubitx the tone when generated from the 740. So I must be TXing milliwatts? My first thought would be to replace the IRF510s.
On Wed, Aug 22, 2018 at 1:46 PM Jerry Gaffke via Groups.Io <jgaffke= [email protected]> wrote: Since you can hear the sidetone, you have U1 working.
Some people have had trouble with the center pin of a coax BNC connector not connecting well
with the BNC socket provided with the kit.? ? Maybe go around that BNC socket somehow during initial tests,
or at least verify the center pin is making a good connection by using an ohmmeter.
?
Does the receiver work?
You will need maybe 60 feet of wire out the window for an antenna before it will hear much.
Do you have some other shortwave receiver around, preferably one capable of receiving SSB transmissions?
With the uBitx, does this other receiver hear a carrier at about 11.997mhz when placed near the uBitx?
You should hear that during both transmit and receive.
Does this other receiver hear attempts at transmitting CW into a dummy load when placed near the uBitx?
Does it hear SSB transmissions from the uBitx when placed near?
Could be that the transmitter is mostly working, but the final amplifier is not.
Jerry, KE7ER
On Wed, Aug 22, 2018 at 01:16 PM, Evan Clark (OSC) wrote:
Hi all,
?
I'm somewhat new but I've spent a lot of time looking on these forums for a solution to my issue. As a disclaimer, I started this project knowing almost nothing about electronics, save ohms law and the like.?
?
When I first got my ubitx I plugged it in WAY before I ever should have, ie before I was even halfway done. This blew my U1, or it shipped faulty, either way that has been replaced. Now I have it at a point where it should be working perfectly but, of course, it's not. Connected to a dummy load and power meter, I get 0 watts out when yelling into the mic, as well as when shorting the key jack to ground. With the mic, it switches into TX and I can hear the relay click. When in CW, I get the click, it's switches to CW, and I hear the side tone. Still, no power out.
?
I have a multimeter, but again I'm quite new to all this so use laymens terms if possible. Thanks!
?
-Evan Clark?
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Re: UbitX no RF out SSB and CW
Since you can hear the sidetone, you have U1 working.
Some people have had trouble with the center pin of a coax BNC connector not connecting well
with the BNC socket provided with the kit.? ? Maybe go around that BNC socket somehow during initial tests,
or at least verify the center pin is making a good connection by using an ohmmeter.
?
Does the receiver work?
You will need maybe 60 feet of wire out the window for an antenna before it will hear much.
Do you have some other shortwave receiver around, preferably one capable of receiving SSB transmissions?
With the uBitx, does this other receiver hear a carrier at about 11.997mhz when placed near the uBitx?
You should hear that during both transmit and receive.
Does this other receiver hear attempts at transmitting CW into a dummy load when placed near the uBitx?
Does it hear SSB transmissions from the uBitx when placed near?
Could be that the transmitter is mostly working, but the final amplifier is not.
Jerry, KE7ER
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On Wed, Aug 22, 2018 at 01:16 PM, Evan Clark (OSC) wrote:
Hi all,
?
I'm somewhat new but I've spent a lot of time looking on these forums for a solution to my issue. As a disclaimer, I started this project knowing almost nothing about electronics, save ohms law and the like.?
?
When I first got my ubitx I plugged it in WAY before I ever should have, ie before I was even halfway done. This blew my U1, or it shipped faulty, either way that has been replaced. Now I have it at a point where it should be working perfectly but, of course, it's not. Connected to a dummy load and power meter, I get 0 watts out when yelling into the mic, as well as when shorting the key jack to ground. With the mic, it switches into TX and I can hear the relay click. When in CW, I get the click, it's switches to CW, and I hear the side tone. Still, no power out.
?
I have a multimeter, but again I'm quite new to all this so use laymens terms if possible. Thanks!
?
-Evan Clark?
|
Re: Intermodulation Performance
Kees, ? In no way am I questioning the strategies you and the team are working through. But can you educate me as to why uBitx doesn¡¯t just use programming to simply select the appropriate band-specific low-pass filter such as presented by this 9-band $34 kit at ? Will low-pass filters not correct the spurs generated as well as harmonics? Thanks for sharing your wisdom. ? 
? David A Posthuma, WD8PUO ?
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From: [email protected] <[email protected]> On Behalf Of Kees T
Sent: Wednesday, August 22, 2018 3:01 PM
To: [email protected]
Subject: Re: [BITX20] Intermodulation Performance ? Allen and David,
Right now this is just a test to see what the results look like and "if there is a pony in the room". We may just provide the Gerber files, the LPF Relay boards, A complete LPF upgrade kit (not sure I can handle the potential demand after the AGC/Click activity), or just give it to someone else to run with ...?
73 Kees K5BCQ
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Re: Intermodulation Performance
Iz
The primary problem caused by high IMD is splatter outside the bandpass of the sideband filter. This shows up on the opposite sideband and on the high (audio) frequency side of the desired sideband. We have all heard this when an overmodulated signal is parked 3 KHz away and we get "static crashes" in the 3 KHz that we are listening to. On a waterfall is shows up as a broadening of the base of the signal.
I don't think you will find the IMD products affecting the intelligibility of the audio even at the very high -12 dBc levels I measured. What did happen is the transmitted noise floor on the opposite sideband and outside the filter rose 20-30 dB over the the single tone level. If there is interest I can replicate that test and show what it looks like on the spectrum analyzer.
WA8TOD
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Re: Nextion 3.2 for CEC 1.097
#ubitx
Hi Darren, VE3XLT
Can you make this correction to? CEC 1.097 Nextion screen for my basic 3.5" display?
TA2FU Alper
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Re: Intermodulation Performance
I greatly appreciate your efforts and that of the rest of the team. ? David A Posthuma, WD8PUO 1 (616) 283-7703 ?
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From: [email protected] <[email protected]> On Behalf Of Kees T
Sent: Wednesday, August 22, 2018 3:01 PM
To: [email protected]
Subject: Re: [BITX20] Intermodulation Performance ? Allen and David,
Right now this is just a test to see what the results look like and "if there is a pony in the room". We may just provide the Gerber files, the LPF Relay boards, A complete LPF upgrade kit (not sure I can handle the potential demand after the AGC/Click activity), or just give it to someone else to run with ...?
73 Kees K5BCQ
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UbitX no RF out SSB and CW
Hi all,
I'm somewhat new but I've spent a lot of time looking on these forums for a solution to my issue. As a disclaimer, I started this project knowing almost nothing about electronics, save ohms law and the like.?
When I first got my ubitx I plugged it in WAY before I ever should have, ie before I was even halfway done. This blew my U1, or it shipped faulty, either way that has been replaced. Now I have it at a point where it should be working perfectly but, of course, it's not. Connected to a dummy load and power meter, I get 0 watts out when yelling into the mic, as well as when shorting the key jack to ground. With the mic, it switches into TX and I can hear the relay click. When in CW, I get the click, it's switches to CW, and I hear the side tone. Still, no power out.
I have a multimeter, but again I'm quite new to all this so use laymens terms if possible. Thanks!
-Evan Clark?
|
Re: 80 meter bandpass filter
Jim, it sounded strange to me as well. But most qrps have just a final transistor and all the harmonics have to be filtered out. In the uBitx the push pull configuration of the PA attenuates the even harmonics so the corner can be shifted some Mhz allowing more bands to pass (eg.? 80 and 60m).
Il 20/ago/2018 23:46, "Jim Tibbits" < ab7vf1@...> ha scritto: Aha!!!! photo of "80 meter" bandpass filter on my ubitx ...L20, L21, L22 as swept? ..corner frequency is closer to 6 mhz than 4
Jim
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Hi Jack,
Yes, most programing optimization is in the design and the chosen solutions to the problem you are trying to solve. That is a bigger picture than the smaller optimizations that the complier can make. Your RDC example is good case in point. Once and a while I'll be trying to optimize some critical tight piece of code or unique algorithm, but my work is mostly, now, working with people to define their business or system problem, breaking that down to a design and coding it.
Most of the efficiency and robustness comes from the overall design, efficiently representing the data for manipulation, and having a good sense of what established libraries perform the low level stuff the best. But, you can't do that if you haven't understood the basics of good code design and what you might be relying on the complier to optimize for you.
Great, thanks for that information, I'll look for the assembly file, these tiny processors are a wonderful back to basics opportunity, I'll enjoy looking at that code. Was thinking I'd use an object dumper and hope the symbol table was included in the elf file.?
I should dig deeper into the Arduino tool chain, I imagine there must be a config file where I can change the complier flags or there may still be a make file somewhere, it would be fun to shut all the optimizations off and compare the results. And force myself to go back to when it was necessary to do the optimizations yourself as a fun exercise.
Your examples for your students sound like they worked to leave an lasting impression of what you were trying to get across. It would probably be necessary to be more politically correct nowadays. But the off-the-wall examples are fun. Now days with algorithms determining who's product is shown first, whose app gets shown first in an App Store, or what ads go to the top of the page, gaming the system is prevalent. While thankfully way more subtle than your eliminating poverty example, attempts to skew the data are involved in gaming the system.
Tom, wb6b
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Re: Intermodulation Performance
Warren, you did quantitative tests that surprise me to a certain extent. Surely the uBitx is not an IC-7300. Even my SWL ears find the IC-7300 transmitted audio one of the best ever. But as I continously monitor my transmitted audio with an IQ SDR receiver I have not found the TX audio that terrible. Mine may sound tinny, the BFO is almost 1khz far from the passband but the opposite sideband seems to me quite well rejected. Does the audio sound distorted? Not really, reports were fine. I imagine that the IMD products may give more problems within the filter passband rather than outside. Maybe it would be worth to test the IMD with digital modes like PSK and see the reports by others.
Il 22/ago/2018 17:23, "Kees T" < windy10605@...> ha scritto:
>
> Hello Warren Allgyer,
>
> I want to thank you for all the effort you have put into the uBITX spur/harmonic problem definition and the excellent data presented. I realize your project is shelved ....but, would you be interested in trying out an 8 relay switched LPF board with 4 plug in LPFs using the parts off the uBITX board. You ran an experiment like that earlier with a perf. board. I have boards (75mm x 62mm) coming in soon and can supply the relays and misc parts (no charge).
>
> 73 Kees K5BCQ
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This entire journey has been a real tickle for me. Now if I can just get JackAl out the door!
Jack, W8TEE
On Wednesday, August 22, 2018, 3:24:59 PM EDT, Des Watson <desw@...> wrote:
Jack,
> Today's compilers are smart enough they might generate the jump table
> anyway!
Exactly so. Having spent many years studying and writing compilers and
optimisers, I see that today's compilers can produce astonishingly good
code, usually *far* better than any hand-written assembler. The
implication is that it's almost always better to code applications (even
time-critical real-time applications) in a high-level language.
> That will allow you to see the assembly code for the program by load
> that file into any text editor.
Good plan. I always asked my compiler students to look at the code
generated by a good compiler with an optimising backend (like gcc or
llvm). It's a most educational exercise!
And thanks for all the contributions to this list - such a help in
getting my uBitx going and teaching me so much about RF design.
Best wishes
Des, G3YXO
|
Jack, Today's compilers are smart enough they might generate the jump table
anyway! Exactly so. Having spent many years studying and writing compilers and optimisers, I see that today's compilers can produce astonishingly good code, usually *far* better than any hand-written assembler. The implication is that it's almost always better to code applications (even time-critical real-time applications) in a high-level language. That will allow you to see the assembly code for the program by load
that file into any text editor. Good plan. I always asked my compiler students to look at the code generated by a good compiler with an optimising backend (like gcc or llvm). It's a most educational exercise! And thanks for all the contributions to this list - such a help in getting my uBitx going and teaching me so much about RF design. Best wishes Des, G3YXO
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Re: 80 meter bandpass filter
What say Jim?
Sure looks that way to me I've done same, without the messed up relays and wiring around them.
I've said in the past the filters work they are corrupted by the surrounding layout and relay wires.
Allison
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Re: Wow... 15 volts in and a bunch out..
Arv,
>>>From tests by Allison, Warren, Kees, and others it seems that part of the problem?
may be in drivers for the IRF510s.? As these devices run out of gain at higher?
frequencies they start generating garbage(?).? If that is true then part of the solution?
would seem to be fixing what gets into the IRF510s before it gets there.??
Receive side has not received much attention other than recent IMD comments, but?
Maybe fixing the transmit drivers is worthwhile to look at.?? Yes, but also over simplified.? The IRF510s or RD for that fact have a lot but not infinite gain.? So at some point you have to supply the needed drive or things decay. Its also true if the various stages have inadequate frequency response the result is over driving to get some power.? it is unclear if its totally in the power amp or in the earlier stages, likely both. You have to think about what you say when the word "clean" is applied to the power amp.? Clean means what ever you put in is reproduced faithfully at a greater level.? So spurs in means spurs out.? That is what filters solve for us. When applied to a practical amplifier it means minimum intermodulation distortion, low harmonic content for a given design, and also stable under mismatched loads.
>>>I have not talked with Farhan?about this but maybe there could be an upgraded
uBITX version to replace the present?design and incorporate what we have
learned.? Have we learned enough yet for that to be?a viable direction?
I think so.? It clearly indicated skimping on filters for simplicity is a false economy.
The idea of wide tuning may be ok for receivers if one acknowledges the number of birdies increases but they are otherwise annoying but harmless.? On the transmit side its unacceptable. Allison
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Re: 80 meter bandpass filter
Jim,
Are you just sweeping the existing filter on the uBITX board ?
73 Kees K5BCQ?
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Re: New Group Specifically for "Homebrew Test Equipment"
Count me in.? "DIYtestgear"? or? DIYtestlab" or "DIYelectrotest"?
--
Jon Titus, KZ1G
Herriman, UT USA
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Re: Wow... 15 volts in and a bunch out..
Jerry,
For some that is a mountain. Others maybe an afternoon.
I tried to balance it with very few new parts, no involved
measurements, maximum HF functionality with
improved filtering.
For the "but 10M" I offer with straight though using the mentioned filter
will solve the 10M issues both harmonics and spurs.?
That filter type would likely work for 12M and 15M with the
appropriate frequency filter.
Allison
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Re: Intermodulation Performance
Allen and David,
Right now this is just a test to see what the results look like and "if there is a pony in the room". We may just provide the Gerber files, the LPF Relay boards, A complete LPF upgrade kit (not sure I can handle the potential demand after the AGC/Click activity), or just give it to someone else to run with ...?
73 Kees K5BCQ
|
Re: Wow... 15 volts in and a bunch out..
I use a 78s05 voltage regulator , at 2 amps it gives a bit more headway and runs cooler .
On Sun, 19 Aug 2018 at 4:23, RCBoatGuy via Groups.Io <ijnfan-HamRadio@...> wrote: From the sounds of it, this temperature measurement was taken in open air, indoors @ room temperature.? It will get considerably hotter in an enclosure, and even hotter yet if that enclosure is outside in direct sunlight on a summers day.?
I strongly recommend both the heat sink and the resistor, especially if you plan on using this outdoors.?
73,
Carl, K0MWC
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Re: Wow... 15 volts in and a bunch out..
Jerry, Allison, etc...
From tests by Allison, Warren, Kees, and others it seems that part of the problem
may be in drivers for the IRF510s.? As these devices run out of gain at higher
frequencies they start generating garbage(?).? If that is true then part of the solution
would seem to be fixing what gets into the IRF510s before it gets there.?
Receive side has not received much attention other than recent IMD comments, but
Maybe fixing the transmit drivers is worthwhile to look at.?
The original BITX was based on fixed gain amplifiers.? This eliminated level variations
due to frequency.? Maybe we can only get a few DB from a 2Nxxxx but by fixing the gain
per device at some level that will not have it pushing up against its maximum gain-frequency
limit at any frequency where it is bing used, we could have the same drive at all frequencies.
This may require that several lower gain stages would be needed in place of one higher
gain stage, but still could provide necessary gain and clean output at all frequencies.?
We have learned a lot since the uBITX became available.? All this is probably of limited
value to the present uBITX without extensive modifications.? I have not talked with Farhan
about this but maybe there could be an upgraded uBITX version to replace the present
design and incorporate what we have learned.? Have we learned enough yet for that to be
a viable direction?
Arv
_._
On Wed, Aug 22, 2018 at 11:50 AM Jerry Gaffke via Groups.Io <jgaffke= [email protected]> wrote: Allison,
That summary is much appreciated.
Looks like a reasonable to-do list,
anything much more than that and we may as well rebuild from scratch.
Thanks!
Jerry, KE7ER
On Wed, Aug 22, 2018 at 10:21 AM, ajparent1/KB1GMX wrote:
On Wed, Aug 22, 2018 at 08:31 AM, Jerry Gaffke wrote:
Yes, the whole thing needs a re-think.
But other than adding external LPF's (or hacking the existing relay scheme),
I'm wondering if there are any other easily performed improvements
that owners of v3 and v4 boards can do.
OK this is radical by some belief.
First give up on the idea of 20mhz and above too many tough fixes needed.
Both fixes are not fun but make sense for believable accomplishment.
NOTE:? it does nto disable 20mhz and up.? An external BANDPASS
filter could be used with 10M and would work better with this change.
see?
Power amp help:
*Replace Q90 with BFR106 or SMT 2N2369A
*C81 470 to 1000pf to keep the 80m power in balance.
*Replace all of the 3904s with 2n2222A? (predriver and driver)
Optional mod:
The IRF510s are mounted with .45" leads and is bad practice in power amps.
Its possible to shorten them to under .09"
Required materials, two insulator kits and suitable heat sink for case anticipated.
It improves power out some? at 10M.
* Remove IRF510 and remove heatsinks.
* bend leads 90 degrees up at the case.
* insert leads into board from bottom so that IRF510 case touches.
* use heatsink insulator kits and heatsink.? Heatsink must be grounded
? for better stability.
Filter help:
* remove the relays KT1 though KT3 an K3.? (replace if damaged).
* disable the use of K3 for audio switching it causes issues.
* remove all the interconnecting traces for RF paths for all.
? DO not cut the traces to the relay coils on the RF ones.
* Using COAX jumper from K3 to K1 for RX path. Ground braid
? ends of the underside ground plane.
* Reinstall relays on the underside!
* using short wires from the input side and output side of the fitlers
? to the relays NO contacts.
? KT1 is? 20/17M filter
? KT2 is? 40/30M filter
? KT3 is 80/60M filter.
?K3 is antenna transfer from jack to RX or TX fitlers.?
* jumper the NC contacts for each relay.
* daisy chain the wiper contacts from one relay to next.
* mod the code to select the right relay for band.
This is a tested set of modifications.? With it you loose 20mhz (unless you use external filter)
and up but the filter issue is FIXED for the lower bands.? If some one wants to write it up
I can help.
Allison
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David Posthuma
TA2FU
Marc Jones