Re: What does zero-beat sound like?
#ubitx
Just a thought: ?It seems to me to be without question that if one were to allign/adjust/tune an oscillator to a precise frequency by listening for a zero beat with respect to a known reference frequency that the higher the reference frequency the greater the accuracy with respect to alignment of the oscillator. However, if done by human ear the entire procedure is only as precise as the individual's ability to detect the a a absence of low frequency audio signals. So for someone like me who has been yelled at by kid's, dogs and other assorted life forms for 63 years the theoretical may be a bit of a moot point?
On May 29, 2018 6:58 PM, "Jerry Gaffke via Groups.Io" <jgaffke= [email protected]> wrote: I have no idea what the various software releases for the uBitx are doing.
But during calibration, the BFO should be placed in the center of the 12mhz crystal filter?
so a zero beat can be heard.
Also, the accuracy of that zero beat is proportional to the frequency of the signal.
So a zero beat to WWV at 15mhz is 15 times more accurate than a zero beat of a 1.0mhz AM broadcast station.
The three local oscillators are each a strict ratio of the 25mhz reference,? ?and from post 44515
the operating frequency of a stock uBitx in LSB mode is:? ? vfo - (clk1-bfo)?
By the distributive law of algebra, a 100ppm change in vfo, clk1 and bfo will result in a 100ppm change in the operating frequency.
JerryOn Tue, May 29, 2018 at 03:38 pm, Glenn Anderson wrote:
When tuning in an AM station when your rig is listening on SSB, you will hear a carrier tone... This will vary depending on whether you change your frequency up or down... When you tune so that the frequency you hear gets so low that it "disappears" then you have "zero-beated" on the station... Most commercial rigs have a tune button that typically is at every 25 or 100 khz on the dial...
Once you no longer hear the tone then that's when you calibrate your dial... A good frequency on air is WWV @ 10.000Mhz...
I hope that helps,
Glenn VE3JAU
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Re: Heat proofing the ubitx.
Very nice.? This is another reason for me to get a 3d printer.? Which kind is yours??? I posted this picture before of my temperature controlled variable 20mm fan.? Not much spare room in my case which is why the fan and filter are on the outside. -- Lee - N9LO? "I Void Warranties"
?
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Re: ubitx assembly confusion, help needed
See attached photo for the pin connections on the molded-plastic 3.5 mm jacks.
--
Jon Titus, KZ1G
Herriman, UT USA
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Re: The new uBITX boards are here
Well this jogged my memory when I used 21 figure logs and 15 figure Sine tables . Both books about 3" thick. Cosines and tangents are calculated from the Sine tables using trig functions.
The 'calculator' was a dual hand cranked machine with both halves coupled for 28 SF.
Was in Civil engineering and setting starting points from distant trig points.?
Peter Paul Fox G8HAV
Mid-Cheshire Amateur Radio Society
5 Llandovery Close
Winsford
Cheshire CW7 1NA?
Group Controller
Dane Valley?RAYNET?
Tel: 01606553401 (H)
Tel: 07919315547 (M)
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lovely recollection of my 1st job doing optical design by using? BIG "BIBLE" LIKE 7 FIGURE LO AND SINE COSINE ETC BOOK -- WAY BACK IN 1964-65
?Thaniks Kevin
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Re: Need Clarification on uBitx v. 4 Schematic
In answer to Mike's question, the RD15*/RD16* parts are an alternative to the IRF510's.
But they are not magical, just stuffing them into the uBitx will not improve things by much,
there are a number of mods required to make good use of them.?
And considerably more mods required to address the issue of getting sufficient gain
at 30mhz from the preceding? 2n3904 stages.??
I suggest waiting for Allison and others to arrive at a good recipe?
before blindly butchering boards.
Jerry
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On Wed, May 30, 2018 at 10:27 pm, Mvs Sarma wrote:
i suppose that RD16HHF1 are to be used.? Some people experiment with RD15HVF1 too. They feel that 21 and 28 mhz performance would improve.
but you might suffer poor performance at 80m band etc
?
. . .
?
On Thu, May 31, 2018 at 9:50 AM, Mike <msmith@...> wrote:
Regarding the new version 4 schematic:
Do new components Q942 and Q952 connect in parallel with the IRF510's as per schematic or
are?the RD15HV's meant to be used as an?alternative to the IRF510's?
Thanks,
Mike
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Can't find the post, but I think Allison has already answered this in the affirmative.
Could stick with the 2n3904's if gain is reduced from 16dB per stage to around 10dB.
But then need a fourth driver stage.
Allison is chasing hotter parts so it can just be a matter of replacing parts rather than adding?
extra parts, a possible manufacturing solution for hfsignals.
But an easy way to add a stage to existing boards might be to remove C84, then add a
small daughterboard to the back of the uBitx with a $1 MMIC on it to bridge the
through-hole pins from RV1-wiper to Q912-base??
Available gain at 30mhz from the 2n3904's is the big one here, but there may also be
other stuff such as board layout issues and torroid core choices, and quiescent currents
to be addressed.? Unless you are keen to help diagnose these problems, best to just
sit on your hands?till Allison and others report back.
?
Jerry
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On Thu, May 31, 2018 at 04:18 am, Kelly Jack wrote:
So my question is could this be solved by adding another amp stage allowing for lower gain at each stage but still using parts from the generic end of the spectrum?
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do you still have the unit ?\
I would like to buy it
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looking for a ubitx board
My ubitx got hit by a power surge and I am looking for a board locally before ordering from hfsignals. SO if you have a ubitx unbuilt and willing to part let me know.
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Re: Heat proofing the ubitx.
I think I can blame android for the 4th paragraph.
Basically I meant to say that I had to redesign the shroud to fit the larger heatsinks and that I only have very slight warming with prolonged ft8 tx.?
A wood case fits over the bright red parts.?
73?
Dave
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I did not get good results with this
mod, I found 80 meters had reduced output. It is also difficult to
implement, since to remove some of the parts, you need to remove
the FETs first to get to them, at least I would have had to do
that.
I did another mod that was easy, and also helped, along the same
idea as Ashar's. I put a small cap from the top of VR1 to the
wiper. The value needed depends on where you set the pot. If the
pot is set to the top end, then it won't help at all. The problem
with all these transmitter mods is that we are pushing the parts
to there limits, and when you design without margin, you don't get
consistent results. This is kind of how we got in trouble with the
original design to begin with, where the design compromises were
made to keep the cost down. My original 3 part mod, which you did
works fairly reliably. Allison is working on replacing the
existing parts with new parts to improve the performance, which is
great. I have taken a different track and am working on a new
transmitter power train. The problem with that is you need a new
PCB.
On 5/31/2018 6:49 AM, Rob Bleumer wrote:
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Hi all,
I did the same mod as Nigel G4ZA did but using FT37-43 giving
30uH? in series with R86?
and 2 ceramic disk C's 220 pF.
And? al with exact the same power output
results!!
Now I see another mod by Ashar Fahran? changing C81 to 470pF.in
the new uBITX.
Could I do the mod by Ashar too and will this give a better
result???
Who can advise me about this?
Rob PA0RBL
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Any chance the ubitx could be offered via Amazom with the price to reflect the additional fees. The reason I ask is I have some Amazon gift cards to use up.
Tx Joe N7QPP
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There are a number threads with the power train mods being discussed and I've lost track of where I read some comments I think between Farhan and Allison about using easily obtainable parts in the tens of thousands in the transmit chain as being a limitation on part choices.? What seems to emerging as an issue is that replacing components in the current transmit chain circuit to increase output at higher freqs is that the current architecture requires finding parts closer to the unobtanium end of the spectrum.
So my question is could this be solved by adding another amp stage allowing for lower gain at each stage but still using parts from the generic end of the spectrum?
73
Simon
VK3ELH
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Re: New VK4PLN Audio Daughter Board + BCI
I believe there are many pin-compatible replacements for the LM324 for those who want better audio noise performance. For example MC33179, MAX414 - although many through hole DIP parts are reaching end of life for manufactureres. No need to change to two dual parts.
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Hi all,
I did the same mod as Nigel G4ZA did but using FT37-43 giving 30uH? in series with R86?
and 2 ceramic disk C's 220 pF.
And? al with exact the same power output results!!
Now I see another mod by Ashar Fahran? changing C81 to 470pF.in the new uBITX.
Could I do the mod by Ashar too and will this give a better result???
Who can advise me about this?
Rob PA0RBL
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Re: New VK4PLN Audio Daughter Board + BCI
Hi Nik,
You could put the audio amp on there like a 2n3904 replacement version per the new ubitx version. Or some AGC circuitry?
Or one of the more sophisticated pop suppression circuits (admittedly not a clean installation as what you have designed here given need to link to traces on the board).
Could the SMM2167 stand vertically to conserve space for other stuff?
73
Simon
VK3ELH
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Re: boosting the power on 28 MHz
#ubitx
Depends on the regions. In Europe 10 meters are open for e-sporadic in may and June every year. Anyway many vhf and uhf transverters have the IF at 28, so I'm my opinion it is important to have it fully functional even when the band is closed.
Il 31/mag/2018 09:39, "Terry Morris" < terry.kb8amz@...> ha scritto: In the late 80's too. KB8AMZ
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Re: The new uBITX boards are here
lovely recollection of my 1st job doing optical design by using? BIG "BIBLE" LIKE 7 FIGURE LO AND SINE COSINE ETC BOOK -- WAY BACK IN 1964-65
?Thaniks Kevin
On Thu, May 31, 2018 at 12:45 PM, Kevin Luxford <kbgluxford@...> wrote: Well you will just have to fall back on your Chambers Seven Figure Mathematical tables.? Or perhaps you can get your hands on a Monroematic electric calculator or even one of those crank and shift jobs we used in Physics labs 60 years ago.
73, Kevin VK3DAP / ZL2DAP
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Re: boosting the power on 28 MHz
#ubitx
In the late 80's too. KB8AMZ
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Re: The new uBITX boards are here
Well you will just have to fall back on your Chambers Seven Figure Mathematical tables.? Or perhaps you can get your hands on a Monroematic electric calculator or even one of those crank and shift jobs we used in Physics labs 60 years ago.
73, Kevin VK3DAP / ZL2DAP
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Re: Need Clarification on uBitx v. 4 Schematic
i suppose that RD16HHF1 are to be used.? Some people experiment with RD15HVF1 too. They feel that 21 and 28 mhz performance would improve. but you might suffer poor performance at 80m band etc
On Thu, May 31, 2018 at 9:50 AM, Mike <msmith@...> wrote: Regarding the new version 4 schematic:
Do new components Q942 and Q952 connect in parallel with the IRF510's as per schematic or
are?the RD15HV's meant to be used as an?alternative to the IRF510's?
Thanks,
Mike
-Mike
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Lee
_Dave_ AD0B
Paul Galburt - K2AYZ
Terry Morris