Re: Harmonic performance - SSB vs CW
Allison,
Since you have your uBITX apart, have you checked the individual values of the parts to see if they are to spec ?? The schematic says the low Band LPF should be three 900nH inductors and 1nF, 2nF, 2nF, 1nF capacitors.
73 Kees K5BCQ
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Re: Harmonic performance - SSB vs CW
I¡¯m not suggesting it, I¡¯ve done it.? With a good outboard LPF set, it works and can be compliant with the right set of filters. ?
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From: [email protected] [mailto:[email protected]] On Behalf Of ajparent1/KB1GMX
Sent: Monday, August 6, 2018 11:11 AM
To: [email protected]
Subject: Re: [BITX20] Harmonic performance - SSB vs CW ? Madradiomodeler,
Would not have suggested it if it wan't minimally tested first.
I have a set of Low pass and band pass filters in pomona boxes
with SMA connectors.? Very handy.
If one rips out L1-4 plus the associated caps and uses decent
7 element low pass for the same band groups as the existing f
ilters and a band pass for 10M (4 filters) the result going to
the amp nets a 35db minimum improvement in the raw amp
output.? Not quite good enough to go live without low pass
filters but significantly better.
Allison -- ¡_. _._
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Re: Harmonic performance - SSB vs CW
I removed the 80 meter toroids and assembled them, along with the requisite SMD 1000 pF caps on the underside, in line of perf board.? I cut the RF trace from T11 to the relays and routed it out to the new filter via teflon coax.
The 3rd harmonic of the 80 meter CW signal is marginal but would pass FCC scrutiny at -46 dBc. Higher order harmonics are obliterated.
Remember this is CW on 80 meters, far and away worst case. This filter is fine. It is a layout issue.
WA8TOD
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Kees,
V4 is identical.? I looked.
Initially I looked at it and thought it clever.? Then it started nagging at me.
The contact capacitance or isolation is worrisome. Did a maybe the relay
has majik and it works.? Testing was, Oh, my!
As to your conclusion. Resistance is very small save for dry and hopefully
bifurcated contacts and the right?material or it will age badly and maybe
become open(intermittent).? ?Long term issue.
More relays and better layout, Exactly.? ?
I'd also opt for better placement of the TR relay and paths.
No need for three control lines for?4 states as well.? ?I'm sure many would
want to have a spare IO? pin.? I did!
Allison
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Re: Harmonic performance - SSB vs CW
?yup....pretty sad.? ?This is progress, however!!!!? ?
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For everyone to see...
Here is a sweep of the 1970s Tentec Century 21 filter board the 3.5mhz filter.
Its a simpler 5 element and would be marginal with the current -43dbc spec.
It's day and night better.? its image C21b
I include as well the 3.5mhz filter in the ubitx. A presumably better 7 element
filter. Image F35
Allison
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Ok Sam .
Tr¨¨s? bien parfait.
Michel? F1GTX
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Re: Harmonic performance - SSB vs CW
For everyone to see...
Here is a sweep of the 1970s Tentec Century 21 filter board the 3.5mhz filter.
Its a simpler 5 element and would be marginal with the current -43dbc spec.
It's day and night better.? its image C21b
I include as well the 3.5mhz filter in the ubitx. A presumably better 7 element
filter. Image F35
Allison
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I just looked at the uBITX schematic for 2017 (I believe it to be level V3) and looked how the band switching of 4 LPFs is done with 3 Relays KT1 - KT3. I assume V4 is wired the same way ?
The 3 relay control signals are TXA (KT1), TXB (KT2), and TXC (KT3) which come from the Raduino board.?
The 4 stages of TXA/TXB/TXC are (0 indicates relay not "picked", 1 indicates relay "picked")?:
0,0,0 which selects the High Band LPF and uses 3 series?relay contacts,
1,0,0? which selects the Hi Midband LPF and uses 5 series relay contacts.
1,1,0? which selects the Lo Midband LPF and uses 7 series relay contacts
1,1,1 which selects the Low Band LPF and uses 7 series relay contacts.
That's a lot of series (resistive) relay contacts and associated (capacitive) wiring. Adding one more relay,? and associated driver, could cut that down to a max of 2 series relay contacts for each band and "bus" type LPF wiring (less overall wiring).?
73 Kees K5BCQ
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Re: Humble suggestion future Ubitx versions
#ubitx
Last month QST did a write up on the BITX40, with all the published lab tests.? It would be interesting if they were do the same with the uBitx.? ??It might get FCC attention and stop all future imports to the USA,? is that what we want?
?Maybe it is time to tone down all the attention to these problems.
Just a thought.
K6KWQ
?
Sent from for Windows 10
?
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Iz oos,
For some its was the FT817 for 109$.? There is a lot of distance and people complain about the FT817!
I also agree if you transmit, do so cleanly.? Its a kindness to friends around the world? The bitx40 is far cleaner.
As to many rigs... guilty.
For hf I have two old Tentec the 505 QRP 5 band and its bigger brother the 340 100W 5 band.
I have no worries depite the fact they were design in the 19070s that they meet current standards
or maybe even exceed them.
More modern a Ft817 and the Tentec Eagle.
That and KNQ7A, KD1JV Slopbucket20, WM20, and Diz's 1W, for the
kit radio world.? Then I have my first 20M SSB , 10M SSB, 15M SSB,
radios from the ground up.? All meet the numbers required and then some.
All have decent carrier suppression.? The only one with issues that needed
help was the KNQ7A that being a really loud pop on TX, easy fix too.
Others manage to do it well and inexpensively and with attention it works.
As is the ubitx has more of my time in it than a few scratch builds including
building their? filters and PLL systems(pre Si 5xx parts).
Mine however is in the "junkbox" as a result of slicing it up to get to root causes.
Its salvageable but a clean sheet would be less time consuming.
Allison
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All,
when I first looked on the schemtaic of the ?BITX I felt a bit
sceptical about the way how the low pass filters are switched.
Only one relay for input and output of the lpf? What about the
crosstalk within the relay?
So my scepticism comes true.
Personally I always would use two relays one of the input and one
for the output, even short circuiting the non switched filter. And
remember: every relay contact has a few pF of capacitance. This
will add to the existing filter cap.
The remedy would be an extra lpf board.
And in addition please also use bpf?s in the transmit and receive
path in order not to overdrive the first stages / mixer.
Recently i read an interesting blog from an austrian ham: he
destroyed xtal-filters when his high performance (high IP3)
receiver was connected to a high performing antenna! Out of ham
band stations were overdriving the stages--- please remind that
xtal filters do not want "high power signals" in the range >0
dBm even at stop band!!!
Henning Weddig
DK5LV
Am 06.08.2018 um 18:26 schrieb Kees T:
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Allison,
Yes, I see that another thread (Harmonic performance - SSB vs CW)
is also discussing the same subject and the plots are
"troublesome". No offense, but I hope those plots were taken
"correctly" ......50 ohm impedance matching and terminations,
proper grounding, etc. Looks like some work to be done. Might be
interesting to understand how the original testing was done.
Yes, any filter with x pF connected from input to output screws up
the filter performance. I have seen that many times in the testing
I have done with my old Marconi SA/TG.??
This will be interesting and fun to resolve.
73 Kees K5BCQ
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Kees,
I've done this for commercial work so accepted techniques and methods applied.
I have a bin full of SMA attenuators and all.??
Signal introduced at pin12 of KT1 and ground next to it via a sma terminated piece
of RG316 duobraid and the output at the normal?antenna port with a SMA connector.
Two pads at each end and normalization check for cal.? Problably should have put
in the directional coupler in to see what the S11 looked like for all cases but by then
I was sufficiently shocked to say forget it.
The one picture was with all the relays not energized.? So we have the TR relay
open and the default 30mhz filter in place as its on the NC contact set.
If the relays and layout were decent that should have the max attenuation possible
which in this case is noteably poor.? The rest of the images is what the TX filters
actually do with K3 Energized and the various?filters selected.? ?Warren got a
poorer numbers but, adding the relay shield does help but not anywhere near
enough.?
Also the board segment was literally isolated from the rest.? I even applied a layer
of tape on each relay to give it a grounded shell (about 3db improvement midband).
Let say this I gave it every chance to look good.? It didn't.
I have a low pass filter board from a Tentec Century 21.? Its only a 5 element filter
(ca1975ish) but it performs as expected.? I included C21b plot for 3.5Mhz.
It was an issue when trying to flatten the amps gain and at about 60db (q90 to output)
it would sing like a bird at about 19-23mhz at full power.? ?Cut the boards up and
the amp was much more well behaved.? Seems the relay despite switching the RX
line to ground were a potent feedback path.? The only reason all of them do not
oscillate is at the mid to high end the gain is well down (8 to 11db).?
Its a fundamental board layout issue that goes beyond a few bits of coax or better relay.
There are not enough vias and stitched pours to establish a good current return path.
I have a VHF differential probe for EMI/RFI work and the board between any two
points ground to ground is quite live.? The current paths are poorly controlled
and not localized.
Image of the sliced board included.
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Re: Harmonic performance - SSB vs CW
Hans
Guess that I am a typical US American because I had that mis-conception.?
Arv
_._
Hi Arv, all
> Also noted is that the harmonic and spurious levels are perfectly okay for 3/4? > of the world where they do not have FCC level limits, or even an equivalent? of? > the FCC.??
This is perhaps a misconception that is quite common in US. That the US has the FCC that has strict limits, but everyone else doesn't. In fact most countries have similar regulatory bodies with similar regulations, in some cases MORE strict than FCC.?
73 Hans G0UPL
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So could I, for example, use Ian's software to do a WSPR transmission on a given band, and then use the RSP1A and SDRplay's spectrum analyzer software to get a good look at the frequency content of the transmission, and then I'd know for my installation, what the actual spurious emissions would be?
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Oui! Nous avons fait la m¨ºme chose.
On Mon, Aug 6, 2018 at 4:06 AM, Sam Tedesco <stedesco619@...> wrote: Merci. J'ai fait un nouveau tft. Je dois le tester aujourd'hui. Je vais essayer le v?tre aussi. On Sun, Aug 5, 2018, 10:49 PM Michel Dupuy < 82f1gtx@...> wrote: bonjour,
Voici le fichier modifi¨¦ pour que le S/Metre aille ¨¤ S9 .
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That¡¯s what I was thinking. ?
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From: [email protected] <[email protected]> On Behalf Of ajparent1/KB1GMX
Sent: 06 August 2018 17:01
To: [email protected]
Subject: Re: [BITX20] One question only... ? Alan,
I believe your approach is sane.
The back half TX and filters can be improved.? The easy way is a whole mezzanine
board with cleaned up power switching, band pass filters amp and output filters
can be done.?
Its worth doing as it also make for the builders/makes the difficult part of a radio
the power amplification and filtering and makes it if done well a component not
unlike arduino and its shields.
Then do a tweak on the font half to fix a few things and we have three boards
that plug and play or can be modded to suit.? Its filtering the bathwater, saving
the baby.
Allison
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Re: Harmonic performance - SSB vs CW
Which after-market board is that? I would like to keep any new boards in the same case. ? Colin ¨C M5FRA ? ? ?
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From: [email protected] <[email protected]> On Behalf Of MadRadioModder
Sent: 06 August 2018 16:45
To: [email protected]
Subject: Re: [BITX20] Harmonic performance - SSB vs CW? ¡°rip out the filters and the relays and even the TR relay (KT1-3 and K3) and route everything to an external low pass board.?¡° ? Yup, done, works¡ gains almost 30bd in suppression with a good/cheap after-market board. ? From: [email protected] [mailto:[email protected]] On Behalf Of ajparent1/KB1GMX
Sent: Monday, August 6, 2018 9:52 AM
To: [email protected]
Subject: Re: [BITX20] Harmonic performance - SSB vs CW ? Warren,
Not so much disagree as wow! that's terrible... can't be!? Yes, its horrific.
5 images.
NF1 is RX mode with no filters (default is 30mhz) selected and RF applied at RX amp output
and measured at antenna connector.? It is really bad!
F3.5 is TX mode, 3.5mhz filter selected.? The blow by limits us to barely 25DB at 30mhz.
F70 is tx mode, 7mhz filter selected.? Blow by limits us to maybe 25db.
F21 is tx with 21mhz filter selected. blow by limits us to about 30db at 30mhz, not impressive.
F300 is TX with last filter 30mhz, span extened to 50mhz so we can see it.? at 45mhz we
are barely 30db down.
Results, we can argue magnitude but over all the filters are unacceptable in situ.
The first one (NF1) was the one that caught my eye as its pure blow by as there is no
direct path its all random coupling.? That has to be much better before we even
consider filters.
At this point I'd rip out the filters and the relays and even the TR relay (KT1-3 and K3)
and route everything to an external low pass board.? At that point I think we have a chance
with the external board performance being unknown but for certain cannot be worse.
--
¡_. _._
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Re: Humble suggestion future Ubitx versions
#ubitx
Iz oos,
For some its was the FT817 for 109$.? There is a lot of distance and people complain about the FT817!
I also agree if you transmit, do so cleanly.? Its a kindness to friends around the world? The bitx40 is far cleaner.
As to many rigs... guilty.
For hf I have two old Tentec the 505 QRP 5 band and its bigger brother the 340 100W 5 band.
I have no worries depite the fact they were design in the 19070s that they meet current standards
or maybe even exceed them.
More modern a Ft817 and the Tentec Eagle.
That and KNQ7A, KD1JV Slopbucket20, WM20, and Diz's 1W, for the
kit radio world.? Then I have my first 20M SSB , 10M SSB, 15M SSB,
radios from the ground up.? All meet the numbers required and then some.
All have decent carrier suppression.? The only one with issues that needed
help was the KNQ7A that being a really loud pop on TX, easy fix too.
Others manage to do it well and inexpensively and with attention it works.
As is the ubitx has more of my time in it than a few scratch builds including
building their? filters and PLL systems(pre Si 5xx parts).
Mine however is in the "junkbox" as a result of slicing it up to get to root causes.
Its salvageable but a clean sheet would be less time consuming.
Allison
|
Thanks so much! I totally missed that (old age and fatigue!). Flipped and recompiled and all is good, so far. Now on to getting the S-Meter working.
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On 8/6/2018 6:26 AM, gary@... wrote: I am certainly not an expert but stand taller when I am on the shoulders of others!? Recently trying to find out how to "expand" the display to make use of my 4.2" I believe I may have your answer.? With your current file loaded into the Nextion Editor select the Device ID tab on the top.? That will pull up the list of devices supported, most likely with your highlighted as well as the Basic and Enhanced buttons.? On the left side you will see DISPLAY.? Click on that and you can select one of the four possible orientations.? Close that menu and back at the top find the Compile button, click that.? Then in the very top menu select File, Open Build Folder and you will find the edited .tft file to install in your display.? Hope you find this correct, let me know.
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Allison,
Yes, I see that another thread (Harmonic performance - SSB vs CW) is also discussing the same subject and the plots are "troublesome". No offense, but I hope those plots were taken "correctly" ......50 ohm impedance matching and terminations, proper grounding, etc. Looks like some work to be done. Might be interesting to understand how the original testing was done.
Yes, any filter with x pF connected from input to output screws up the filter performance. I have seen that many times in the testing I have done with my old Marconi SA/TG.??
This will be interesting and fun to resolve.
73 Kees K5BCQ
|
Re: Raduino Clone kit from W0EB-N5IB
#ubitx
Several have asked about sending just the bare board internationally in an envelope and I originally said I couldn't do that.? I have had problems sending PC boards this way in the past but now the USPS has an option to allow envelopes with RIGID contents to be send regular International First Class for a reasonable price and this price depends on the destination country.
I have changed the pricing information on to reflect this.
73,
Jim, W0EB
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MadRadioModder
Arvo W0VRA
Jim Sheldon