Re: End Fed antennas w/ uBITX
#ubitx
Gordon Gibby <ggibby@...>
Thanks, Jerry!!!!!
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The “heat” measurements are very much appreciated!!!!!
I’m going to send this to the folks in our area
Gordon
On Aug 3, 2018, at 01:33, Jerry Gaffke via Groups.Io <jgaffke@...> wrote:
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Re: 12MHz xtals and QER Filter
Ashhar Farhan
wow, rahul. meticulous work! i will try this out soon. - f
On Fri, Aug 3, 2018 at 10:47 AM, Rahul Srivastava via Groups.Io <vu3wjm@...> wrote: Hi!,
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Re: End Fed antennas w/ uBITX
#ubitx
Jerry Gaffke
I did that back-to-back test of two myantennas.com matchboxes.
I'd say they are plenty efficient for my purposes from 3.5 to 30 mhz. My 2 year old matchbox is referred to here as xfmrA. Text on the box says EFHW-8010, should be exactly like the one reviewed in the March 2016 issue of QST. I popped this one open long ago. It's pretty much as described on that facebook page where they are trying to build clones.
https://www.facebook.com/groups/EndFedHalfWaveAntennas/ Got two stacked toroids, each has an OD of 2.43", ID of 1.40", height of about 0.5" each.
Has 14 turns of enamel copper wire 0.072" diameter, doubled up on the first two turns
for the primary 50 ohm connection. A couple caps in series across the 50 ohm port,
the facebook page seems to think the series combination is 100pf.
The SO239 port and the grounding post are adjacent at the bottom, have their
grounding tabs soldered together for a short and hefty connection.
That mechanical support eyebolt at the top has no internal electrical connection.
Facebook page thinks the toroids are Mouser PN 623-5943003801, which is at least the right size, no idea if that's the right material. But before trying to roll your own, look over that facebook page. Apparently not as trivial as you might think to hit multiple bands like this. Also borrowed a newer matchbox, about 2 months old, label says MEF-330-1K. This was bought as a separate matchbox, not part of an antenna system. I believe the only significant difference between the two is a vent to the atmosphere on the side of this new one, not present on the old one. Referred to below as xfmrB Here's the raw data: -----2500-ohms----- ----50ohm-load-----------------
xfmrA xfmrB ohms-in vout-for-50v-vin
3.80mhz 45.6+j3.2 45.4+j5.9 38.3+j11.5 48v
7.20mhz 41.7-j5.5 45.3-j4.3 37.4+j1.6 52v
14.25mhz 31.8-j3.9 33.5-j4.3 31.8+j4.7 60v
21.35mhz 33.6+j6.9 35.4+j6.4 42.3+j12.7 48v
29.00mhz 67.0+j12.9 65.3+j14.0 63.0+j1.5 38v
First column shows input impedance of xfmrA when output has 2500 ohms across it. Second column shows the same for xfmrB Third column shows impedance into the xfmrA coax port, xfmrA is hooked back to back with xfmrB using wires of 1 or 2 inches, and xfmrB has a 50 ohm dummy load on the coax port. Fourth column shows peak voltage across the dummy load of the above back to back arrangement when xfmrA is driven with 50v peak of RF. Impedances were measured using the AQRP Vector Impedance Analyzer from Kees. The voltage measurements were made with a Rigol DS1052E using a single 10x probe. The probe was first used to scale the RF source for 50v at the input port, then the probe was moved to measure the voltage across the dummy load. I don't have a lot of faith in this Rigol, but should be fine for such relative measurements. I chose a 2500 ohm load for the matchboxes when measuring their impedance, as this should give close to a 50 ohm input impedance given the 1:7 turns ratio of the toroids. The measured impedance was somewhat less in all cases except 30mhz. So for some reason the transformer seems to exhibit an impedance ratio in excess of 1:49 at most frequencies, and thus gives a good match for an end fed halfwave which typically has an impedance somewhat greater than 2500 ohms. Given that the input impedance was mostly lower than the 50 ohm load impedance in that last column, it's not too surprising that the output voltage sometimes exceeded the input voltage. But there are some weird anomalies in those figures I haven't quite figured out, and I'm not totally convinced my measurements are accurate. At all frequencies, the dummy load got plenty hot. The toroids of the box I had taken the lid off of did not. ################################# A few more general notes, not part of the measurements presented here. I've measured SWR into my EFHW antenna system, my figures agreed with the QST article and with the charts on the myantennas.com website. I believe the charts on myantennas.com were created with 100' of RG8X coax from matchbox to the SWR meter plus RF source. My SWR measurements with a very short coax showed higher SWR figures out-of band, but the SWR was perfectly fine within the bounds of most bands (not all of 80m or 10m). The SWR minimum is pretty well centered on a usable part of each band, due in part to the small airwound coil in the wire near where it enters the matchbox. A possible exception is 80m, the SWR min is centered on the CW portion of the band, a tuner of some sort would be needed to use it at 4.0 mhz. Given that an RF source can pump power into this antenna system without anything getting hot, I can only conclude that most of that power is properly radiated. In what pattern it gets radiated is debatable. Here's an FAQ for this antenna system: https://myantennas.com/wp/f-a-q/efhw-antennas-f-a-q/ Near the bottom are four links, clicking on the first we see plots for a straight half wavelength of wire at 40 foot above the ground. http://www.qsl.net/kk4obi/EFHW%20Straight.html Ideally, an 80m antenna would be a half wavelength above the ground for an optimal pattern, so 40 meters, or 130 feet. I'd bet most hams with an 80m antenna aren't climbing trees and rooftops much higher than the 40 foot of the plots shown in that last link. At 40 foot, the 80m plot shows it's going pretty much straight up, a good NVIS antenna perhaps. The others all show lobes that look to me as if they could do some good for DX. For any ham who plans to use 80m, this EFHW is nearly equivalent to a dipole at the same height. The other bands are gravy, and that gravy doesn't look bad. Yes, having several different antennas would be better. A 30 mhz rotatable beam is easy enough, and would work much better than this wire. But for some of us, it's just a hobby. Jerry, KE7ER
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Re: ubitx CW straight key wiring
Mike Woods
dkuk I want to thank you for pointing out this error on ubitx.net. I have fixed this temporarily by removing both the photos from that page and by deleting the reference to the hfsignals.com wire up error (now out of date) The original wiring diagram and circuit diagram on hfsignals.com were in error. The error in the circuit diagram was subsequently drawn to list members attention, and I updated the circuit diagram on ubitx.net accordingly. HF Signals subsequently fixed their circuit diagram and I purged a number of references to the wire up and circuit diagram instructions error. Obviously I missed one! It is regrettable that you (and perhaps others?) have taken the photo as the guide to wiring up their manual key in this manner, and come to grief with the ubitx going directly into TX mode. For that I can but apologise. Unfortunately this problem wasn't commented on earlier. Maintaining ubitx.net is a bit of an undertaking. The guide will, from time to time, become a bit out of date, because there is a very active community of hackers. However, I certainly don't want folk burning through finals or getting a really bad steer. So if anybody spots an error, I attend to these as soon as they are drawn to my attention. It's normally best to write direct to info@... for the fastest response. 73 Mike ZL1AXG ubitx.net
On 2/08/18 1:29 PM, dkuk@... wrote:
I've gone through 2 rounds of blowing finals before I finally found it mentioned that the wiring in the manual for the CW straight key was wrong.
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12MHz xtals and QER Filter
Rahul Srivastava
Hi!,
I have been scratch building a uBitx and had been experimenting with the 12 MHz QER filter. I have noted few things and adopted some from various postings on group. 1) With the set of xtals that I have with 100pF caps and 200Z I/O filter BW is around 1.85Khz for HC49S xtals and 3.3Khz for HC49U xtals. With filter based on HC49U xtals lower BW is achieved using 150pF caps but impedance drops down to 150-160 ohms. Lowering the BW also de grades the shape factor to around 1:2. This can be well understood considering that HC49U xtals have a lower motional inductance Lm. 2) As suggested by Alsion 82pF is working just fine in the filter. With BW of around 2.2Khz. Capacitor value is bit touchy between 82 to 100pf. 3) Q of capacitors used has a major impact on filter response. Parallelling 2 values to arrive at desired value results in a better response. I am attaching sweeps of few different combination's on my SNA. I would love to hear from others regarding their experience in this regard. 73 Rahul VU3WJM
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Front Panel Stereo Socket Board Wiring Layout
The front panel stereo socket board wiring layout for universal case for ubitx has been published. 8 pin relimate female to female connectors are used for digital and analogue connectors on ubitx board and the front panel board.
For mic ptt, volume, encoder, speaker TVS connectors have been used with right angle pins.The case comes now complete with these accessories too.Those that want the wire kit or complete kit with board can get from our website amateurradiokits.in Pictures for front panel board. https://groups.io/g/BITX20/photo/6439/7?p=Name,,,20,1,0,0 https://groups.io/g/BITX20/photo/6439/8?p=Name,,,20,1,0,0 use any wire but follow the wire sequence. Kindly report if any mistake found. best of 73s Sunil VU3SUA
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Re: hacking bitx40 for 20 metre
#bitx40
Ryan, Hints sent to your youtube page based on KNOWN performance of similar Renesas mosfet in parallel operation for bringing power up to region 14W RF out. Timothy E. Fidler : Engineer BE Mech(1) Auckland , NDT specialist AINDT UT /RT3 , MT2
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Re: Tinny sounding electric miss on uBitx
Arggh an assumption re-arranged makes an Ass out of you and me.!!!. I thought Ashar F would have gone done the merry conventional way with pulling the BFO to get sb flip ..
so next time you want Space shuttle Field joints and O rings re-designed AP .. you know where NOT to go. Every single photo I have seen of uBitx or ubitx40 seems to have half height xtals on it so either AJP got a premium build or TEF needs better specs or a bit of both. :-).
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Re: Tinny sounding electric miss on uBitx
ajparent1/KB1GMX <kb1gmx@...>
OK, we have a lot of misunderstanding here... uBitx.
If the master osc is not set on frequency everything else is likely to be off frequency and work poorly. The filter is ladder filter (not a Cohn) and like all ladderfilters due to the parallel caps are loaded to the lower frequency. so technically it is a filter of about 2.1Khz with a center frequency a of 11.9989mhz built with nominal 12mhz crystals. From here out we call it a 12mhz filter as 11.99989 is just longer! ;) Also the default startup setting for the software uncalibrated is 11.995 (at least 1khz too low). The IF filter 12mhz has a roughly 2.1khz pass band with the upper edge just below 12mhz and the bottom ends around 11.997ish Small errors in BFO placement (100hz) is enough to impact audio quality both RX and TX. FYI OSC-0 is the BFO. In mine the magic number was 11.996750mhz. NOTE: the BFO is not changed to change sideband. ubitx changes sideband by flipping oscillator 1 between 33mhz and 57mhz with a small correction for the 45mhz filter that is not at 45mhz but about 5-10khz lower. If the calibration is off or not done correctly these oscillators will be off for the 45mhz filter and sensitivity will suffer (if far enough off). Now if the 25mhz crystal on the Raduino board is off and generally they will be its the master oscillator for the whole game. So the first thing is to get the "calibration" dialed in so when the MPU/software commands xxx frequency you actually get it and the other two oscillators are also where they should be. Changing out the crystals in the filter can improve the filter but not likely solve the "tinny sound" as that set will likely have a different offset for the BFO. FYI changing the parallel capacitors will also move the filter center frequency and the bandwidth requiring BFO change. They are not SMT they are conventional leaded HC49U parts and easily desoldered without art or rework station. If the BFO is right the low end should cut off at about 200hz and the high end around 2300hz. That will not be tinny. For an FYI: I included a image of the filter pass band while testing a personal mod to get to a wider band width (2.7khz) for better fidelity. The ripples on the top of the pass band are about 1.5db and not at all bad. Even widened up the upper edge is barely 12mhz (11.999985ish mhz). Best sideband setting is 11.996685mhz for that filter. Allison
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Re: any tips for debugging RFI issue?
#ubitx-help
Mike KK7ER
Allison,
Thanks for all the suggestions! Regarding your points:
73 Mike KK7ER
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Re: ND6T AGC and Click kit wiring notes
Scott McDonald
Both if it’s easy?😳
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72 Scott ka9p Make something good happen!
On Aug 2, 2018, at 6:37 PM, Nick VK4PLN <nickpullen@...> wrote:
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Re: hacking bitx40 for 20 metre
#bitx40
ajparent1/KB1GMX <kb1gmx@...>
IRF510 at 20M is not an issue or even working hard.
I have several radios that really work on that band using that critter. Bitx20 (V0) from the early years, uBitxV3, Slopbucket 20 a Kd1JV design. Never minding a 10M radio that just got an upgrade from 2sc1307 to IRF510 (went from 5W to 12), a 160 to 10M amp using them (WA2EBY). Makes me ask what's wrong? Allison
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Re: hacking bitx40 for 20 metre
#bitx40
Ryan Flowers
Terry, I did this. I also changed the PA FET for a RD15HVF1 because it worked a lot better on 20m than the IRF510. Info on both here:
http://miscdotgeek.com/converting-bitx40-20m/ https://www.youtube.com/watch?v=-1u-cANWMTM -- Ryan Flowers - W7RLF MiscDotGeek.com Multi Band BITX40 The BITX40 FAQ
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Re: Tinny sounding electric miss on uBitx
Sorry . brain fade.. invert the answer. Jack clearly had to set the BFO way Low to select USB so it would pass the Cohn filter which appears to have its passband low on 12.0000 but the issue still remains.. does the uBitx work correctly on a frequency that uses LSB such as 40m. I would guess not unless the firmware was utterly bullet proof Mil Spec. Re comment on LEon.. He may refuse the work as he deals only with 10 Meg IFs on the kits he sells. AND you would need to put the squeeze on someone you know with a a Hot air chip removal station for SMD to remove all the affected crystals if the kit refuses to work properly on both sides of the IF. sometimes you may have to put up with something with limited functionality than the worst case outcome....
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Re: Tinny sounding electric miss on uBitx
Jack it is not a problem - it's FEATURE ! But if you were setting this up on a system which has to swap USB/LSB between 40 m and 20m, which yours will since you are uBitx .. I suggest you need to check it works on USB after you have done the cludge ie on 20m as it is clear to me you are talking LSB operation and thusly 40 or 80 for your fix.. I kind of see probos ahead, unless the firmware is incredibly smart.
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Let's face it though at the price it sells for the Cohn filter sets are not going to all be exactly on 12.0000 Mhz. If you talk nicely to Leon at Ozqrp and offer him what he wants for matching and ship him say 12 HC 49U full hght xtals for matching you might be able to correct the problem. But you need to get an indep and traceable calibration frequ counter on the BFO and get a second opinion as to if it is the BFO or the xtal filter set... just my tuppence worth.... Timothy E. Fidler : Engineer BE Mech(1) Auckland , NDT specialist AINDT UT /RT3 , MT2
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Re: nextion 3.2" display question..
Kevin Rea <reakevinscott@...>
OH,, ok..thanks.
Kevin
From: BITX20@groups.io <BITX20@groups.io> On Behalf Of AC0AX
Its for the Real time clock. its not needed for now. if someone implements it in the firmware then it could be used.
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Re: nextion 3.2" display question..
AC0AX
Its for the Real time clock. its not needed for now. if someone implements it in the firmware then it could be used.
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nextion 3.2" display question..
Kevin Rea <reakevinscott@...>
hi guys,
what is the battery holder for on the nextion display ?? something we need ? kevin rea lancaster, calif. k6rea
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Re: ND6T AGC and Click kit wiring notes
Kevin Rea <reakevinscott@...>
never mind.. i just received it today.
thanks, kevin rea
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Re: ND6T AGC and Click kit wiring notes
Hi Again.
Would folks prefer the Pot to adgjust the ACG or the Jumpers as per Kees' boards? I am in 2 minds about it,,, 73 Nick. VK4PLN
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