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Re: New Group Specifically for "Homebrew Test Equipment"
Gilles F1BFU Thanks for your comments.? Moderators do not have to be technical specialists. The task of moderating a discussion group seems more like "herding cats" than verifying technical claims.? The rest of the group will make sure technical statements are accurate and timely. Thanks for giving me the opportunity to comment about "herding cats". ?? 8-) Arv K7HKL _._ On Mon, Aug 20, 2018 at 7:27 AM F1BFU - Fr - 79 <gilles.f1bfu@...> wrote:
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Re: QRP SWR meter recommendation?
#ubitx
¿ªÔÆÌåÓýI would also recommend the ZM-2 tuner if you do need a SWR meter reading.It has a resistive bridge to protect your rig, very fast to tune, and the range is amazing. ?You could likely tune to low SWR on a pool umbrella with it! ?Now that I think about it...Maybe I will give it a try this week!? Best regards, |
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Re: QRP SWR meter recommendation?
#ubitx
Hi Mike,
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The tuner itself does not care how much power you use to 'set' it as long as it isn't *more* than it can handle. It is not impressed if your TX can pin the needle or not. If your uBitx will only drive the meter to half scale in it's "Forward" configuration then set the "Cal" knob full right. Flip the switch to "Reverse" and adjust the tuner for minimum as per usual. If you can get it all the way to zero - well zero is still zero. And less is still less. So what if you can't read that it is 1.25 to 1 if it is 1.25 to 1. A zero in "Reverse" is 1:1 no matter how high the TX didn't drive the needle in "Forward". I built an SWR bridge that could be pinned with less than two watts (maxed at about 30) and discovered that it doesn't make any difference as described above. What does make a difference is a tuner and SWR bridge built for QRP power levels can be made much smaller and lighter:) Put the tuner and the bridge in the same box together for even more convenience out in the field. Like a scaled down version of your MFJ. If you build it into your uBitx you will forfeit using it with other radios but will be even more convenient when taking the uBitx to the field. Keep us posted with progress. 73, Bill KU8H On 08/20/2018 11:31 AM, Mike KK7ER wrote:
So far I have been setting the antenna tuner using my Kenwood and then --
bark less - wag more |
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Re: New Group Specifically for "Homebrew Test Equipment"
Dennis I will keep you in mind for a Moderator.? I'm still working on a few loose ends and then will be back on the new test equipment group effort.? Thanks again, Arv _._ On Mon, Aug 20, 2018 at 6:02 AM Dennis Zabawa <kg4rul@...> wrote: How about:?Test Equipment and Measurement as a name for a new group?? I had proposed this for the eHAM site in the past and would be glad to be a moderator for the group. |
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Re: QRP SWR meter recommendation?
#ubitx
On Mon, Aug 20, 2018 at 09:37 AM, Jerry Gaffke wrote:
If all you want is an SWR meter and are on a budget,I second that.? Cheap and easy.? I have a few around here, one standalone in a box. Some of the others are built into a radio.? Does the job. Allison |
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Re: Low Power Output for Hendricks BitX20A - Watt meters and Scope readings do not agree....
#bitx20
What you believe and what I've found to be the case after careful testing of setups is
yes, you can get that kind of accuracy. The back up was HP 5753C and Agilent 5357A Network analyzers.? Within factory cal is sloppy answer, then I ask for the cal sheets of the test systems.? Used to do metrology back when so if its simply tested fine, its not calibrated.? If you want a cal you need better usually not less than 10X better and traceable. As to gadgets that includes HP power meter, Boonton, various diode mounts, RF sources with fixed known output, Lots of Minicircuits attenuators and several step attenuators.? We are talking RF shop, not hobby lab. To get accuracy you need to be able to repeat a measurement and do so with consistency.? If you can't then ask why and fix it. So yes I can.? I'd add often its not needed at all. Allison |
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Re: How to use cheap Chinese Arduinos that come with with CH340G / CH341G Serial/USB chip (Windows & Mac OS-X) ¡¤ by Konstantin Gredeskoul (@kig)
Konstantin If you have a computer running Linux (Debian or Ubuntu works in "run-from-pen-drive" or run-from-CD" so you don't have to do an install) you can use the Arduino IDE to write to your less expensive Arduino devices.? You can also use the Arduino IDE to re-install the boot loader.? Linux...Just Works!? No drivers needed. Arv _._ On Mon, Aug 20, 2018 at 2:45 AM Tom, wb6b <wb6b@...> wrote: I have two cheap Nanos that won't program over the USB serial port (many others that are OK), to see if it would resurrect them I flashed new boot loaders using another Nano programed as a Arduino ISP. I was able to flash new boot loaders but the USB chips are likely bad on those Nanos.? |
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Re: QRP SWR meter recommendation?
#ubitx
I'm able to tune on the same tuner with a non Bitx/uBitx with 6 watts. 73 Ken VA3ABN On Mon, Aug 20, 2018 at 11:31 AM, Mike KK7ER <groupio@...> wrote: So far I have been setting the antenna tuner using my Kenwood and then swapping in the uBITX.? But now we want to take the uBITX on the road.? Problem is that the uBITX does not put out enough power for full deflection on our MFJ versa tuner II so we cannot get an accurate SWR reading to tune the antenna.? Does anyone have recommendations for a QRP SWR meter?? Thanks! |
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Re: uBitx ¡®hoots¡¯
#ubitx
On Sun, Aug 19, 2018 at 02:09 AM, M6OIB wrote:
y question is when I¡¯m listening on a number of frequencies it hoots, or oscillates, specifically on 1.900.000, 3.001.400, 3.601.800, 5.145.500 and many more, even with no antenna. I¡¯m concerned this is something I have caused, or is it a ¡®feature¡¯ of this model of radio?Most of that is what we call birdies.? They are spurious tones(internally generated signals) That you can tune through and tend to tune faster than normal signals via antenna. Its a feature not a bug.? Side effect of doing a wide tuning range. Allison |
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Re: Modular uBitx - "Ex: Harmonics"
¿ªÔÆÌåÓýThanks Gordon / Alison, In the mists of time, along time ago now...... there was a suggestion of what about using 'this or that', off the shelf relay board, I agreed with another contributor that it didn't look particularly "suited to RF" applications. General observation, not a full on analysis. (Just what ever is ultimately chosen should be a best as possible
a "cure all" (to which there is no such thing, we can only strive
to become close) (Some regions are governed by the -50dB rule, we cannot ask you NA / US solutioneer's? be guided by that. It would be nice however not to have to reinvent the wheel to
come up with another solution that satisfies "our legislation"?))
Now it's resorted to quoting Lecher Lines / Skin resistance
and? waving smiths charts at dawn.? :-P
Can we agree the theory of short, direct traces is good "Noodle soup" bad. Well bonded top / bottom groundplanes are good Input traces parallel to output traces, bad Attention paid to layout, Good? and 1001 things that that all can be read in a book, possibly EMFD all contribute to good practice. (Sometimes even that is not enough, and sprinkling 103's liberally everywhere at least shows willing,
or weakness....? :-)
)
It was what I was trying to portray? looking back, at what I wrote. The LPF's work. The physical relay device chosen works, the
problem was how it was all put together
Alan On 20/08/2018 15:02, ajparent1/KB1GMX
wrote:
Alan, |
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Re: QRP SWR meter recommendation?
#ubitx
V Zecchinelli
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So far I have been setting the antenna tuner using my Kenwood and then swapping in the uBITX.? But now we want to take the uBITX on the road.? Problem is that the uBITX does not put out enough power for full deflection on our MFJ versa tuner II so we cannot get an accurate SWR reading to tune the antenna.? Does anyone have recommendations for a QRP SWR meter?? Thanks! |
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Re: QRP SWR meter recommendation?
#ubitx
If all you want is an SWR meter and are on a budget,
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consider this guy from Diz at $12 for the kit: ? ?? The Emtech would be nice though, no need to haul out that MFJ. Might be a way to hack a switch into the MFJ to give a low power option. I'm not familiar with it. Jerry On Mon, Aug 20, 2018 at 08:40 AM, Joe Milosch wrote: On Mon, 20 Aug 2018 08:31:35 -0700 |
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Re: QRP SWR meter recommendation?
#ubitx
Joe Milosch
On Mon, 20 Aug 2018 08:31:35 -0700
"Mike KK7ER" <groupio@...> wrote: Hi, try the Emtech ZM-2 It only handles 15 watts, but is highly regarded. Comes as a kit or pre-built. Youtube has a few good reviews. Joe So far I have been setting the antenna tuner using my Kenwood and then swapping in the uBITX.? But now we want to take the uBITX on the road.? Problem is that the uBITX does not put out enough power for full deflection on our MFJ versa tuner II so we cannot get an accurate SWR reading to tune the antenna.? Does anyone have recommendations for a QRP SWR meter?? Thanks! |
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Nextion 3.2 for CEC 1.097
#ubitx
Is the Nextion 3.2 software available for CEC version 1.097 yet?
Thanks, Bill |
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QRP SWR meter recommendation?
#ubitx
So far I have been setting the antenna tuner using my Kenwood and then swapping in the uBITX.? But now we want to take the uBITX on the road.? Problem is that the uBITX does not put out enough power for full deflection on our MFJ versa tuner II so we cannot get an accurate SWR reading to tune the antenna.? Does anyone have recommendations for a QRP SWR meter?? Thanks!
73, Mike KK7ER (and son KI7ZZS) |
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Re: #ubitx LTspice shootout results.
#ubitx
Spice and other programs and manual calculations may be exact, but components are not.? Reminds me of when I was in college and doing labs.? The school had boxes that had components on bread boards. We would calculate circuits and then build them.? Some worked and some did not.? If you get a 'lucky box' as we called it the components would mostly match the nominal values used in the calculations.? Some boxes seemed to have values out of tolerance? or stacked? to one side of the limits.? They were not made that way, it just happened.? We learned to try and design for the worst case with the active components and let the passive components set the parameters for the most part. On Mon, Aug 20, 2018 at 10:19 AM, Bo Barry <bobarr@...> wrote: One update. This SPICE models aren't exact.? |
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Re: #ubitx LTspice shootout results.
#ubitx
Bo,
Spice may say one winner but your model is wrong. The issues Too low FT, 3904 has ft of 300mhz,? some seemed less so. HFE that depresses at higher currents.? Spice models are not valid for that if they have it at all. Not all parts used have uniform HFE Transformers were likely "perfect" not real. I don't hate the 3904, I use them a lot but trying to get 16db of gain at even 14mhz where the beta is only 21 (Gain of about 13db) isn't a successful path.? If the stage was designed for 10DB it would still be doing well at 30mhz.? ?Then you need more stages of lower gain.? Its just decades of design and build you find out things. The most common issue seen is the drive to the gates of the IRF510s easily hit 400-500mw at 80m and were down to 100mW at 18mhz.? ? This is why turning up the voltage helps. The winner in actual radios was 2n2222A (Not PN2222) and the 2n5109 was better above 20mhz. Why is 2n2222A(to18) better, it has the same FT?? Its HFE increases with higher currents and it can actually handle higher currents.? It also exhibits a increasing current bandwidth rather than? a decreasing one(3904).? So its better, but not best. Also Q90 in many had very low gain in that stage, replaced with BFR106, even 2n2369 was better. Some of the bias values were limiting performance and many of the transformers favored lower HF? and taking a turn off really helped in the midband and higher. Lets take the Q90 stage its feedback and layout suggests a 18db amplifier, the 3904 will produce that to about 5mhz and begin showing decreasing gain from that point with increasing frequency. If we want constant gain to 30mhz we need a transistor with a 1500mhz Ft, that is not a 3904. There are other things but detailing them is pointless as Pspice lacks facility for including board level parasitics unless you measure the board (at RF) and include the results as parasitic components. IF the argument is above 20 is dead...? I don't care.? The problem will still be there. There a string from May/June of about 300 postings about all this.? The string is forgotten the problems persist. Allison |
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Re: #ubitx LTspice shootout results.
#ubitx
Bo Barry
One update. This SPICE models aren't exact.?
A ?transistor beta may be listed as 100-300. ?Not the single value in the SPICE model. Long ago I built a fantastic heathkit MOSFET receiver, used sockets, and moved the ones provided around until the sensitivity was FANTASTIC. .2uV or less I believe. Might get a handful of 3904s and plug and pray. ? Bo |
Alan de G1FXB
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