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Re: Gamma-matching antenna tuner
hirosmb
¿ªÔÆÌåÓýArv,Thanks for your comment. Yes, as Timothy said, I was completely confused that there would have been a gamma-match manual antenna tuner which could have been placed just after the RF output of rig. All what I want is a manual antenna tuner which also works as a LPF, that is to say, a pi-match antenna tuner. BR, // hiro, JJ1FXF
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Re: Gamma-matching antenna tuner
hirosmb
¿ªÔÆÌåÓýAllison-san, Thanks a lot for your info. I am checking those presented URLs and a bit surprised with a huge filter using PC case. :) In my understanding, because uBitx uses DDS and so is not likely to produce lower harmonics such as by frequency multiplier, but higher harmonics may occur in most cases. Also I am afraid that the fixed BPF or LPF (such as until 30MHz) may not suppress the second harmonics (14MHz) when emitting 7MHz CW, but hoping that the pi-match antenna tuner may work for this case. // hiro, JJ1FXF
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Re: End Fed antennas w/ uBITX
#ubitx
Yes you may infer some things and guess and sometimes the type of the transformer. You can grossly guess also the material chemistry of the core. Suppose you have an unknown transformer and you read 50uH at the SO239 and 450uH between the antenna terminals. The ratio is 9:1, 50uH at the SO239 indicates the lowest frequency is around 160m and the core cannot be made of powdered iron. Most likely is ferrite. If you find that there is no dc short at the SO239 and you find around 50uH across the pin of the SO239 and one of the terminal and between the outer of the SO239 and the other terminal you have a 1:1 balun, i.e. a choke which will be fine for all the HF. Now an annedocte. A friend of mine bought for 80 euro from a Ham, a monoband wire antenna with a black box but found difficult to tune. He didn't want to open the black box as he was afraid of breaking it, he paid a lot for it! Well, the inner of the SO239 was not shorted so I excluded it was a 9:1 transformer, I thought the black box contained a 1:1 choke, I mean a quite expensive one. But then I asked to measure the inductance between the inner of the SO239 and the wire and between the outer of the SO239 and the clamp. In both cases it was 0uH!!!..... He paid 80 euro for 20 meters of ordinary unipolar wire and an empty black box!!!! Il 30/lug/2018 20:33, "John Smith via Groups.Io" <johnlinux77=[email protected]> ha scritto: The inductance meter reads 97uH to antenna, and 38uH to ground. The first one I bought that looks like this model and is a 1:1 balun has shielded cable to the toroid and shrink wrapped magnet wire wrapped around it, and looks professional. The inductance readings on the 1:1 balun are 49 and 53uH. This 9:1 unun looks like the typical knock off crap made in the back of a Shenzhen market stall with white shmoo hiding the lies. Are these inductance readings something you expected to see, or way off? |
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Re: End Fed antennas w/ uBITX
#ubitx
If you are into placing your radiation pattern exactly where you want it with a big yagi,
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then a multiband wire antenna is not for you.? Agreed. But many hams are putting up a wire dipole as best they can fit it on the lot into what trees are available.? The radiation pattern is what it is.? An EFHW at the fundamental can work about as well as the more typical dipole with the same radiation pattern, and is easier to put up for mechanical reasons. As a bonus, in my experience it can work very well as a multiband antenna as well. The many lobes at the harmonics actually are not a negative, the dipole isn't? efficient all directions either.? ?Most of us don't have a rotater for our 80m dipole.? Fundamental or harmonics, I'm primarily concerned that it radiate efficiently. If it happens to have a pipeline into Timbuktu and not LA, I'm fine with that. If you don't like the direction it is pointed, try another band and it's a whole new ball game. Trying to make an EFHW into an efficient multiband antenna can be tough. That's why this thread now has 250+ posts. Rather than kick off another storm of posts here, I'll just suggest you?read the EFHW-8010? review in the March 2016 edition of QST. That review squares well with my experiences of that particular antenna. ? ????? Jerry, KE7ER On Mon, Jul 30, 2018 at 01:44 PM, Chuck, N1KGY wrote: Agreed on both comments.? Pursuit of the "All Band Antenna" is the albatross around the neck of many newer hams, and many OMs as well.? The antenna with the least design compromises tend to cover only one band, i.e. a dipole or a (full sized) 1/4 wavelength vertical.?? Can either of these antennas operate (present a reasonable VSWR, and thus 'take power') on other bands, i.e. the 3rd harmonic?? Certainly.? But if we don't examine the radiation pattern produced by said 'harmonic operation' then the utility of the antenna remains undefined, beyond the anecdotal declarations that such antennas "work" for that operator at his/her installation.? |
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Re: The dreaded LSB and USB swap problem again
dan magers
¿ªÔÆÌåÓýThanks Jerry. ?
I had no clk0 when I received it. Found a broken C4 off if pin 10 of the si5351. ?
Looking at all the LOs with the Agilent SA is how I determined why I had no rx or tx. ?
Now that's sorted out I discovered it sounds like it's way out of the 12mc filter passband. ?Or, way down on a skirt. ?
The vfo does not change when I try to set it. ?Goes back to where I started when I exit. ?
Also, the cw keyer works as it should using 2.2k and 10k resistors however, I do not get any straight key function. ?
Plus, ?ssb tx drops off from 10w to 1watt within a couple of seconds. ?
I read where these boards were tested prior to shipment. Hmm...
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Re: The dreaded LSB and USB swap problem again
Dan,
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I assume by circuit description, you mean this from ? ?? "To invert the sideband between USB and LSB, the second oscillator is switched between 33 MHz and 57 MHz." I'd say that's just a casual statement, not meant to be read by someone with a law degree. (But should be corrected.? This has come up before.) The second oscillator is normally at 45-12 = 33mhz for LSB, and 45+12=57mhz for USB. The VFO is normally on the high side, at 45 + operating_freq, putting it on the other side of 45mhz would flip the sidebands (and create lots of new birdies, not recommended). The stock firmware holds the BFO at slightly below the crystal filter, perhaps 11996500 hz. Moving the BFO to 11999500 hz would flip the sidebands. I'm assuming the 12mhz filter passband is roughly 11997000 to 11999000 hz,? that will vary depending on which sorting bin your crystals were taken from. The BFO was made low side to avoid audio tones resulting from harmonics of the BFO beating with harmonics of the 16mhz clock frequency of the Nano. However, the 16mhz ceramic resonator of the Nano is not very accurate, could be off by 100khz. I doubt it makes much difference if the BFO is high or low for most rigs.? Here's a more complete description of what's going on in the stock firmware along with an attempt at explaining why the sidebands flip. ? ??/g/BITX20/message/44515 Jerry, KE7ER On Mon, Jul 30, 2018 at 01:53 PM, dan magers wrote:
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Re: Spurious RF at beginning of CW transmission in the uBitx
Gordon Gibby
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From: [email protected] <[email protected]> on behalf of n1kw@... <n1kw@...>
Sent: Monday, July 30, 2018 4:39 PM To: [email protected] Subject: Re: [BITX20] Spurious RF at beginning of CW transmission in the uBitx ?
It appears that I have solved the problem! While analyzing the circuit further, I realized that the large capacitor C52, which is charged during receive, would feed back through R52 and R18 keeping the receive path (Q10, 11, and 12) after the balanced modulator
"hot" for a brief period. When the transmit path is activated, the receive side of the circuit is going to remain on for some period of time due to the time constants of C52 and its loads. It is understandable that if both directions of the circuit are on,
it could oscillate during that time! |
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Re: The dreaded LSB and USB swap problem again
dan magers
¿ªÔÆÌåÓýI've measured the second LO, clk1 at test point 15 and found it to be 33 and 57 MHz, LSB and USB respectively. ?Opposite of what the circuit description gives. ?So, I assume the sidebands are reversed. ?
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Re: The dreaded LSB and USB swap problem again
dan magers
¿ªÔÆÌåÓýWhere is this "master cal" to be found? ?I have a uBITX V4.3 stock that is way out based in what I'm hearing. ?
Perhaps the BITX20 is entirely different. ?
I'm not very familiar with the Raduino so, go easy. ?
Tnx,
Dan?
N5MRG
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Re: End Fed antennas w/ uBITX
#ubitx
On Fri, Jul 27, 2018 at 09:44 PM, ajparent1/KB1GMX wrote:
Chuck, thank your for the clarity.Thanks for your kind words, Allison? ;P Yes, try, experiment but please do not do the rathole of all band antenna.? The harmonic mode antennas Zepp and friends and derivatives are still good on the higher?Agreed on both comments.? Pursuit of the "All Band Antenna" is the albatross around the neck of many newer hams, and many OMs as well.? The antenna with the least design compromises tend to cover only one band, i.e. a dipole or a (full sized) 1/4 wavelength vertical.?? Can either of these antennas operate (present a reasonable VSWR, and thus 'take power') on other bands, i.e. the 3rd harmonic?? Certainly.? But if we don't examine the radiation pattern produced by said 'harmonic operation' then the utility of the antenna remains undefined, beyond the anecdotal declarations that such antennas "work" for that operator at his/her installation.? Defining your Use Case is foundational to qualifying your results, and yet most hams? - whether they formally develop their antenna requirements at all - don't state what those requirements are.? E.G. NVIS and DX are, essentially, orthogonal propagation modes - an antenna well-suited to one of these modes is almost always a disappointment when examined with regard to it's utility for the other.? The ubiquitous failure by most hams to declare the use case(s) and/or other bounding parameters they are working under, makes antenna design and construction appear more like alchemy than science, but it doesn't have to be that way. Looking higher in the spectrum (V/UHF and above) we see numerous antenna designs which are very broad-banded, and I expect that many folks simply assume such multi-band coverage must be a "natural" consequence of how RF works, and that there "has to be some equivalent design for HF antennas".? They unfortunately overlook the boundaries of design scalability which (in this instance) are dominated by the distinction between antennas operating in free space vs. antennas which interact substantially with real ground, in terms of both input impedance and radiation pattern. ?? Speaking of tuner to match end feds the air core coil and a good air variable in the L configuration are about optimal.? ?Powdered iron cores like T68-2 or -6 are more compact and with care can be very good at low power.? Usually many of the "multiband tuners suffer compromises in switching or possible impedances.? Considering a T68 is under an inch and a good mica padder is small its a low compromise solution for s single band in a plastic box that is both small, light?and compact to carry several, one per band.Also agreed.? The commercial tuners that will "load up anything" present another set of undefined compromises.? I once personally loaded up "nothing" other than the unterminated output connector of an ATU? (a Field Day experience I won't soon forget).? The ATU in question loaded ~100 watts into what was essentially an open circuit shunted by an undefined quantity of parasitic capacitance, to a VSWR reading of <3:1.? Obviously, none of that power was actually radiating, so efficiency was effectively ZERO.? The warning here is that nearly all commercial tuners introduce substantial losses into the system which are unquantified, exactly so that they can claim the widest possible "matching range".? When you design a matching unit (or any other piece of equipment) to a specific purpose, you can effectively simplify the design from the general purpose model, and "re-invest" those gains in higher efficiency applied to your intended use case. The transformer moderated (1:9) random wire is a popular compromise not unlike its vertical cousin the 43ft vertical.? The losses are not too steep but you pay multiple times with mismatch at the antenna, loss in the transformer, and loss in the mismatched cable and likely the added transmatch/tuner.?There are numerous posts and threads across the web discussing the poor efficiency of various commercial and homebrew "all band, no ground radials" antennas based on this design.? At least one commercial model actually has a resistor across the antenna side of the transformer to absorb the high-side? impedance excursions, and there are numerous designs where losses in the transformer alone (replacing the antenna element with a resistor and measuring RF voltage across the known load) were measured to be between 2 and 10 dB.? I find it amazing that so many hams will happily spend $300 to nearly a thousand dollars for a commercial "all band" antenna whose best-case efficiency is -2 to -3dB [typically on 20M] , with losses of 5~6dB common on 40 meters, and 10dB loss not uncommon on 80 meters.? And yes, all these loss figures are *just* for the "matching unit" built into the base of the antenna; so every other form of loss for a particular antenna installation? remains unquantified, and may be substantial in any given installation.? The evidence against the entire category of "all band, no ground radials" antennas with regard to their poor efficiency is overwhelming - yet people continue to waster their time and money on them. If your playing the every milliwatt game its not a good way to go.An opinion: A 80M to 10M antenna is a lot of effort in the light of current solar cycle.A more limited multiband or several mono band antennas offer better performance in tough conditions.? Also for the higher bands there are other possible antennas that are doable due to the shorter wavelengths.? ?Something simple for 10M like the K6STI rectangleoffer advantages over and half wave antenna while retaining simplicity in constructionand mounting.??One last item...? Don't strive to have the the best antenna only to feed it with 50ft of RG174.? I understand if your stuffing things in a pack with 3 days supplies it may be called for but us as little as possible as you are also likely considering only one or two bands for the same reason, weight.In the end the half wave offers much be it end fed or center.? The mechanics of end fedhalf wave antenna are are hard to beat.The sun is implacable, so I rarely bother with 15/12/10 meters these days.? At the (twin) peaks of Cycle 23 (2000 and 2002), and even better at the peak of Cycle 22 (1990~91) 10 meters was often open 24 hours a day, for weeks on end; 15 and 20 meters were seemingly "open to everywhere" much of the time.? Even 6M was open often enough to make it very attractive to casual operators.? But as you state, those are not the prevailing conditions today, nor are we likely to see such favorable conditions for a number of years to come - so most of my effort these days is put towards 160/80/40 meter antennas... when I'm not working on getting a decent station on the air for 475Khz. As to being a "minimalist", i.e. insisting on a QRP station that weighs only 2 pounds (inclusive of battery and antenna) and fits in the outer pocket of a backpack, that's not my obsession.? But I do pursue simplicity, so when I set up my QRP/portable station my preference is for no feedline at all, i.e. with an EFHW whose matching unit is plugged directly into the RF port on the rig.? When I do use coax, such in a hotel room, it's either 6 or 12 feet of reasonably good "RG58 size" cable - presently LMR240 - because "efficiency", and because I don't place a hard limit on myself to do all my operating at QRP levels. That's one of the things I like about the uBitx: I'm not limited to 2 watts (like my SST and Wilderness Sierra) or 5 watts (i.e. my Webber Dual-Bander), nor even to CW...? with the uBitX I am happily getting a bit more than 10 watts output on 40 and ~8 watts on 20 meters. For myself, I enjoy the rigors of the Design / Build / Evaluate / Modify process; both with antennas and more typical circuits - I'm presently working up a "Solar RV Controller", based on an ATMEGA328, that will automatically recognize several common "power use patterns", and automatically switch system components to facilitate those patterns, a.k.a. use cases - i.e. when operating on HF (MF and LF, too), power the radio(s) strictly from battery, isolated from any charger or inverter, so that no electrical noise is conducted to the receiver(s) on the power supply leads.? When you work for an extended period in a process domain, observing proper rigor, you learn things you wouldn't otherwise.? For one example, I recently discovered that not only will sense-leads across a DC circuit breaker indicate to the controller whether a breaker has tripped; I can also obtain a useful voltage measurement across the resistance of the circuit breaker - i.e.using it as a current shunt - this simple method of current sensing is sufficient to determine when the circuit is "in use", as an input to the controller.? The pursuit of simplicity, within the bounds of fitness for the design purpose, yields the most elegant solutions.? Following this path, I have learned many useful techniques which no formal course ever taught me, and this comports well with the underlying purpose of amateur radio: technical self-education, and the advancement of the radio arts. |
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Re: Spurious RF at beginning of CW transmission in the uBitx
It appears that I have solved the problem! While analyzing the circuit further, I realized that the large capacitor C52, which is charged during receive, would feed back through R52 and R18 keeping the receive path (Q10, 11, and 12) after the balanced modulator "hot" for a brief period. When the transmit path is activated, the receive side of the circuit is going to remain on for some period of time due to the time constants of C52 and its loads. It is understandable that if both directions of the circuit are on, it could oscillate during that time! |
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Re: The dreaded LSB and USB swap problem again
Raymond,
Nobody was ever able to explain to me what that Master Calibration number represents, so I never knew what number to add or subtract to nudge it one way way or the other, so I decided to change it by a large amount to see what direction it moved. My Master Cal number was 161675 to start with, so I changed it to 131675 and the frequency dropped by about 200Hz, wrong direction, so I added the same amount to 161675 which resulted in 191675 and that got it almost perfect, then I just nudged it up a little at a time until I settled on 191700. Now I'm within a few Hz. Sorry I cant be more specific, you just have to keep playing with the numbers until you get it where you want it. Really, that Master Cal number makes no sense to me at all. Joel N6ALT |
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Gamma-matching antenna tuner
Would they not just need band pass filters for whatever the desired band is? I kind of see where you might be able to suppress spurious emissions in a tuner, but why? My limited understanding is that the ubitx has filters for hf bands 20 meters and lower. Do they not provide enough suppression?? If not a filter should be pretty straight forward to construct. No? |
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Re: The dreaded LSB and USB swap problem again
¿ªÔÆÌåÓýHi Joel, I am having a similar issue and just can¡¯t seem to hit on the sweet spot. I am right now only .050 off frequency but it is enough to make it annoying. ? My master Calibration is 143000 at the moment for that setting to still be offset. ? Any tips would be appreciated. ? ? Raymond ¨C W9KHP ? ? This email was brought to you by the Numbers 1 and 0. No trees were harmed in sending this email but a lot of electrons were seriously inconvenienced. ? From: Joel Caulkins
Sent: Friday, July 27, 2018 12:15 PM To: [email protected] Subject: Re: [BITX20] The dreaded LSB and USB swap problem again ? Okay, through trial and error I finally have it calibrated, both VFO and BFO. Thanks for all the help. ? |
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Re: Spurious RF at beginning of CW transmission in the uBitx
Generally 10-20MS is fast for a relay.
Keep in mind for 80M, 5 relays have to switch so you always plan for the slowest which in the case of this is a cascade of two. To go to transmit The Raduino activates K1, TX+ is its output and that activates the remaining? 3 band pas filter relays as needed and K3 always. So RX to TX switching is the sum of K1 and K3 switching time.? 20mS would be optimistic. Allison |
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Re: Spurious RF at beginning of CW transmission in the uBitx
A possible firmware fix for the LPF relay delay would be to add a pipeline delay
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to all CW code elements, not just the starting edge of the transmission. The sidetone could happen immediately, so the operator would not notice a difference. Jerry On Mon, Jul 30, 2018 at 11:17 AM, Jerry Gaffke wrote:
At 20 wpm, a dot is around 60 ms. |
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Re: End Fed antennas w/ uBITX
#ubitx
The inductance meter reads 97uH to antenna, and 38uH to ground. The first one I bought that looks like this model and is a 1:1 balun has shielded cable to the toroid and shrink wrapped magnet wire wrapped around it, and looks professional. The inductance readings on the 1:1 balun are 49 and 53uH. This 9:1 unun looks like the typical knock off crap made in the back of a Shenzhen market stall with white shmoo hiding the lies. Are these inductance readings something you expected to see, or way off?
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Re: Spurious RF at beginning of CW transmission in the uBitx
I'd be fine with constantly powering the LPF relays on my rig.
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And may be the best solution. Though does raise power requirements a bit during receive, an issue for those running from a battery.? Those few that care could go to latching relays. Also, we apparently have several thousand uBitx's out in the field now. We need a firmware fix to not be messing with the clocks while transmitting. If that fix can also deal with these other issues, then it's a win for those hesitant to take a knife to their precious uBitx. Especially since most users won't be sending CW at 20 wpm. At 20 wpm, a dot is around 60 ms. Would be interesting to measure how long it takes the LPF relays to turn on after TX_RX is driven true.? There are two levels of relays involved there, first the T/R relay has to supply power to the TX rail.? Maybe 20ms total? And need additional delay to add a margin of safety. So getting iffy. Jerry, KE7ER On Mon, Jul 30, 2018 at 10:29 AM, ajparent1/KB1GMX wrote: Jerry, |
Joel Caulkins/N6ALT
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