Kees,
Did you see the last posting about the filters and the lack of effectiveness?
A few jumpers will not fix that.? Even the filters raw (no relay) are pretty poor.
Imagine a a good filter with a 2pf cap from input to output.? Or better take
one of yours and add that and sweep it.? It degrades the filter significantly.
The telling sweep was in RX mode from the TX (tracking generator) in to t
he relays and the output to the antenna port to the SA.? Its the "blow though"
no relay energized and in RX mode.? That is a serious lack of isolation.
Allison
|
Thanks Allison.? I'm still working my way through Jack's book and C for Dummies, but I see the sketch is right there so it may be possible for even me to go that route soon. Appreciate it.
?
Scott ka9p
?
?
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-----Original Message-----
From: ajparent1/KB1GMX <kb1gmx@...>
To: BITX20 < [email protected]>
Sent: Mon, Aug 6, 2018 10:28 am
Subject: Re: [BITX20] One question only...
Scott,
That may work.? But there will be a lot of switching and what if the filter
does not cover the desired frequency?? You can also use low pass filters?
but the filters have to be switches at the 1/2 to 2/3rds octave and?
again lots of switching and about 5 filters.
I never tried it as the DDS board are cheap and the output is sine wave.
It also makes for less hardware.
Checkout KD1JV site for a design based on that I know works.?
That SWR system uses the Tayloe bridge for SWR and a led.? However the basic DDS output
is very useful as applied to other RF measuring gear.
Allison
|
Re: 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. ?
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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. -- ¡_. _._
|
Hi Bill,
I feel like you. There have being whispers, now it's out.
I don't mind improving on a design by standing on the shoulders of
others,? however I don't have an RF bench, or the expertise to use
the instruments if I did.
(The EFHW thread proves that experts can disagree.....)
However don't throw the baby out with the bath water.
Put it in a shoe box and forget about it, it may take 3 months or
more but ride it out for the time being.
Folks are now taking radical steps finding the route causes, and how
fixes can be implemented to the existing units purchased.
Not every one is in a position to cut up their uBIX however it
illustrates perhaps moving forward the benefits of the modular
approach.
Especially if it's always going to be advertised as a starting point
to something to modify / experiment.
Should we be lacking stage gain or filtering in a signal path we can
hack / replace just that stage.
And not building mezzanine boards top & bottom to overcome the
deficiencies.
It's going to push the kit costs up, we will accept that.
Economies of scale should still make it more affordable than if we
were each doing the same thing on our own.
And we can all continue to do our own builds on a sound design.
(Without a doubt this is probably the reason Farhan did not
find the problems at the modular? breadboard stages.)
For existing kits
The bath water is getting dirty, It was a $109 radio at the time,
for me the fix(s) need to be priced accordingly and integrated.
A box of band selected external filters wouldn't cut it for me.
Before the uBiX came along I looked for alternatives. It's a genuine
question:-
Anyone used / any advice on the N2APB SDR Cube Transceiver? Assembly
only kit @ $209
Alan
On 06/08/2018 15:29, Bill Cromwell
wrote:
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Hi Walt,
From what I have seen in these threads about spurs, harmonics, and
(lack of) filtering the troublesome unintended 'signals' are just
about at the legal limit and slightly over. Over is over.
Unacceptable. The way I use my radio I think the trash can be
sufficiently cleaned up for 'safe', responsible use. It would be
much better if that cleanup took place inside the radio and by
design. It is too late for that. Later I might do some of my own
investigation and attempt to correct the deficiencies. Maybe just
follow what somebody else comes up with. But please don't hold
your breath. I have other irons in the fire:)
I haven't modded mine at all yet and none of the mods for 'more
power' is on my agenda. I like some of the features available in
the CEC software. And something *must* be done about that million
decibel side tone. OMG. I cracked a shop window with that thing!
I have other gear and will be buying more. Hans Summers's QCX and
some other toys from his shop are on my hit list. If uBitx hadn't
shown up in my world I would already be using some of those. When
I decided to buy the uBitx first it was not a rejection of the
QCX:) Those are next.
73,
Bill? KU8H
Michigan QRP Club
On 08/06/2018 09:45 AM, WaltR wrote:
Thanks Bill,
I, as many others enjoyed assembling the bitx40 and the ubitx,
for my
purposes, dragging around a bag full of outboard filters and
other
accessories will not work. Perhaps to some degree I am spoiled
by having
access to high end gear, but I am aware that it¡¯s not prudent to
compare
a Harris to a ubitx. I wish not to besmirch Harris by putting
the ubitx
in the same sentence.
my understanding is the bitx was designed and built as a kit for
those
that wish to assemble, experiment, dabble in Arduino sketches
etc, and
by the number that have been sold obviously has a large
following.
There is a need for a simple solid rig that doesn¡¯t require a
lot of
fiddling about, and is reasonably priced and meets regulatory
criteria.
There should be some warning or reminder that if you plan on
doing any
modifying or hacking that you should ensure that you don¡¯t
produce any
transmitted products that may interfere with other services,
especially
any that might fall in the spectrum allocated to government
agencies and
services, as well as commercial, and international interests.
You might
get away with it in the ham bands but you certainly won¡¯t if you
cause
superfluous transmissions in other spectrum allocations.
Buy filters, there are some great little devices available at
QRP LABS.
Cheers and 73
WRS
IF THE PROCESS IS FLAWED, THE OUTCOME MOST SURELY WILL BE FLAWED
|
Allison,
Why not replace that "troublesome uBITX trace" with RG-174 or RG-188 coax ? Maybe even jumper the ground across the trace to reduce the effect of the "break" in the ground plane.??
i sometimes think I need a second uBITX for "bench experimentation" .....great fun for some of us. This CAN be fixed.
73 Kees K5BCQ
|
Scott,
That may work.? But there will be a lot of switching and what if the filter
does not cover the desired frequency?? You can also use low pass filters?
but the filters have to be switches at the 1/2 to 2/3rds octave and?
again lots of switching and about 5 filters.
I never tried it as the DDS board are cheap and the output is sine wave.
It also makes for less hardware.
Checkout KD1JV site for a design based on that I know works.?
That SWR system uses the Tayloe bridge for SWR and a led.? However the basic DDS output
is very useful as applied to other RF measuring gear.
Allison
|
Bill,
For the sidetone level I replaced R250 with a 10k trimmer to adjust it to a manageable level with headphones. Also check to see what your R253 value on mine it is marked 224 on a V3 board, if yours is the 1k (like the schematic) I would use a larger value trimmer for R250. I also have a V2 board and checked R253 and it is the 224 (220k) resistor too.
Skip Davis, NC9O
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On Aug 6, 2018, at 10:29, Bill Cromwell <wrcromwell@...> wrote:
Hi Walt,
From what I have seen in these threads about spurs, harmonics, and (lack of) filtering the troublesome unintended 'signals' are just about at the legal limit and slightly over. Over is over. Unacceptable. The way I use my radio I think the trash can be sufficiently cleaned up for 'safe', responsible use. It would be much better if that cleanup took place inside the radio and by design. It is too late for that. Later I might do some of my own investigation and attempt to correct the deficiencies. Maybe just follow what somebody else comes up with. But please don't hold your breath. I have other irons in the fire:)
I haven't modded mine at all yet and none of the mods for 'more power' is on my agenda. I like some of the features available in the CEC software. And something *must* be done about that million decibel side tone. OMG. I cracked a shop window with that thing!
I have other gear and will be buying more. Hans Summers's QCX and some other toys from his shop are on my hit list. If uBitx hadn't shown up in my world I would already be using some of those. When I decided to buy the uBitx first it was not a rejection of the QCX:) Those are next.
73,
Bill KU8H
Michigan QRP Club
On 08/06/2018 09:45 AM, WaltR wrote:
Thanks Bill,
I, as many others enjoyed assembling the bitx40 and the ubitx, for my
purposes, dragging around a bag full of outboard filters and other
accessories will not work. Perhaps to some degree I am spoiled by having
access to high end gear, but I am aware that it¡¯s not prudent to compare
a Harris to a ubitx. I wish not to besmirch Harris by putting the ubitx
in the same sentence.
my understanding is the bitx was designed and built as a kit for those
that wish to assemble, experiment, dabble in Arduino sketches etc, and
by the number that have been sold obviously has a large following.
There is a need for a simple solid rig that doesn¡¯t require a lot of
fiddling about, and is reasonably priced and meets regulatory criteria.
There should be some warning or reminder that if you plan on doing any
modifying or hacking that you should ensure that you don¡¯t produce any
transmitted products that may interfere with other services, especially
any that might fall in the spectrum allocated to government agencies and
services, as well as commercial, and international interests. You might
get away with it in the ham bands but you certainly won¡¯t if you cause
superfluous transmissions in other spectrum allocations.
Buy filters, there are some great little devices available at QRP LABS.
Cheers and 73
WRS
IF THE PROCESS IS FLAWED, THE OUTCOME MOST SURELY WILL BE FLAWED --
bark less - wag more
|
Re: Interesting antennas for QRP
Thanks!
The bigger deal is it is a useful addition to the tools we have as amateurs but its not
the only hammer in the box.? As such it has a place.
Allison
|
Re: New "ANTENNAS" group has been formed.
It is not a EFHW only.??
The focus is antennas.
Topics include all antennas, coax/feed lines, matchbox and other tools and instruments.
Allison
|
Re: Harmonic performance - SSB vs CW
So with at least two measurements that concur the filter are useless what's the path?
My suggestion is blow them off the board relays as well. maybe keep K3 if the
external board does not do RX/TX.? Basically a jumper from Tx output to K3 and RX input to K3.
Replace all that with external Low pass board.? Preferably one with decent isolation.
Allison
|
Re: reverse polarity protection (ubitx.net)
Thanks, Allison.
Yes, I believe fuse-first, then diode is what MVS Sarma's solution does, once the reverse polarity of the jack is accounted for.? The wiring diagram on this group's assembly page, however, seems to have no particular dependency.? I guess the fuse would probably go first, assuming it reacts faster than the diode, but the ?BITX would be exposed to the reverse voltage before the fuse blew, and the diode would blow too.
But my understanding of this sort of stuff isn't terribly extensive, so someone probably needs to verify my assessment.? Any suggestions?
Jonathan, KD5CFX
On Mon, Aug 6, 2018 at 11:01 AM, ajparent1/KB1GMX <kb1gmx@...> wrote: A while ago (months?) I stated that fuse first then diode is the preferred way.
You want the diode to block reverse voltage and the fuse to blow to keep from burning
the diode open and destroying the radio.
That needs to be get out to everyone.
Allison
|
Re: New "ANTENNAS" group has been formed.
But we already have very good EFHW & G5RV groups. No need for a center-frd all-band resonant group. ?? Bo W4GHV since '54
|
Re: reverse polarity protection (ubitx.net)
A while ago (months?) I stated that fuse first then diode is the preferred way.
You want the diode to block reverse voltage and the fuse to blow to keep from burning
the diode open and destroying the radio.
That needs to be get out to everyone.
Allison
|
Re: Interesting antennas for QRP
Allison, I've thoroughly enjoyed this discussion here! ?I follow the EFHW group and discussion there is informative.?
It looked like a cute/practical/cheap addition to our ubitx.
I use mine without any SWR concern on all bands with no tuner.
It can be installed in ANY fashion that fits! Mine us a sloping inverted ?V ( actually V, depending on how you look at it).
Having lots of success with it.
Thanks for your informative additions
Bo
|
reverse polarity protection (ubitx.net)
Hi there,
In wiring my ?BITX based on the guides and notes available at , , this group's wiki, and the like, I noticed a discrepancy related to reverse polarity protection.
I believe the diagram with included fuse by MVS Sarma at? has the jack wired in reverse (- tip, + sleeve) of the standard (+ tip, - sleeve).? I suppose wiring it this way could be a good way to test if the fuse will do its job!
I should note that this solution seems preferable to the solution(s) provided in W4RJP's wire-up diagram (v1.9) posted at /g/BITX20/wiki/UBITX-Assembly , where it looks like the fuse and the diode would both blow in the case of reverse voltage, and the reverse voltage would still flow through the ?BITX.? In MVS Sarma's solution, my understanding is that only the fuse would blow, and the ?BITX wouldn't be exposed to any reverse voltage.
Also, I wonder if Mike might consider adding to the reverse polarity page PH2LB's reverse polarity protection solution from here:
I haven't tried it yet, but it seems ridiculously simple, and reasonably effective.? I'd probably still want to add a fuse with that solution, though, to protect against accidental shorts.
Jonathan, KD5CFX
|
Re: 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 TX amp output
and measured at antenna connector.? It is really bad!? What is acceptable is not less
than 70db.? it was also why when I got the amp flat in gain it would oscillate as the output
was more than adequately coupled to the input to support oscillation.? Which is why
I cut the board in half (rear section amp and filters) then that in half with filters separated.
Layout issues abound!
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.
|
To answer the original question, if it might be illegal, make it legal. My solution is using plug and play external low pass filters. And to avoid the issue of spurs pointed out by Allison I don't use SSB on 15 and 12m. For 10 meters I also added a high pass filter.
Il 06/ago/2018 16:42, "Scott McDonald via Groups.Io" <ka9p= [email protected]> ha scritto:
Hi Allison,
?
Do you have an opinion on whether the 5351 with bandpass filters like the QRP Labs set up is good enough for SWR and filter BW?
?
Thanks, Scott
?
?
-----Original Message-----
From: ajparent1/KB1GMX < kb1gmx@...>
To: BITX20 < [email protected]>
Sent: Mon, Aug 6, 2018 8:51 am
Subject: Re: [BITX20] One question only...
I used to use a signal generator (analog), frequency counter, and a diode load
so adding even a digital oscillator DDS or NCO was a giant step forward in
making basic measurements.
If a SA at ~1500$US is out of reach the lowly 9850 DDS and arduino plus a
RF power sensor (8307 or one of the many others) will allow many of the
same measurements at a fraction of the cost in exchange for time to plot
the points.
It is also possible to use the above to plot to a graphic display?
by taking the power sensor output to the analog input of the arduino
allowing graphic display of the results.?
The 5351 is good but the square wave output will mess you up for many
measurements due to the rich harmonic output.? Two common measurements
are SWR and filter bandwidth/cutoff are hard to do with harmonics present.
Allison
|
Re: VU2SPF - TFT_TouchScreen_for_uBitx -- CAT, Split, UP/Down Scan, V2.9BU Released with New User Manual
Hello?SP VU2SPF and Joe VE1BWV,
Im installing your very affordable touch screen. After som trail and error my disply works great.
Untill now I'm impresed with your documentation. I'm almost 68 years old and learning a lot from it.
I got a few questions:
1. Are you still working on improving the software and in which direction?
2. Can I use the KD8CEC LM386 S meter plan as input for pin 66?
3. Could the huge amount of data pins from the Mega 2560 be used to drive a LPB for each of the HAM bands separately??
|
Re: VU2SPF - TFT_TouchScreen_for_uBitx -- CAT, Split, UP/Down Scan, V2.9BU Released with New User Manual
Sorry, No edit posibility...
So you can make an optimal extra LPF board with relay for every Ham Band?
Idea?
Greatings
Rob P J R Bleumer
PA0RBL
|
Re: VU2SPF - TFT_TouchScreen_for_uBitx -- CAT, Split, UP/Down Scan, V2.9BU Released with New User Manual
Hello?SP VU2SPF and Joe VE1BWV,
Im installing your very affordable touch screen. After som trail and error my disply works great.
Untill now I'm impresed with your documentation. I'm almost 68 years old and learning a lot from it.
I got a few questions:
1. Are you still working on improving the software and in which direction?
2. Can I use the KD8CEC LM386 S meter plan as input for pin 66?
3. Could the huge amount of data pins from the Mega 2560 be used to drive a LPB for each of the HAM bands separately??
|
MadRadioModder
Alan de G1FXB
Skip Davis
