Re: Harmonic performance - SSB vs CW
My unit puts out illegal harmonics on SSB on all bands below 20 meters.
WA8TOD
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Re: Front Panel Stereo Socket Board Wiring Layout
Thanks, Ian.? Got it.?
Eddie
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Re: hacking bitx40 for 20 metre
#bitx40
Terry,
You need a separate band pass filter for each band if you want to use the single conversion BitX40. The UbitX uses double conversion that eliminates that requirement. You could use a multiple band pass filter, (QRP Labs has them) but then the cost is getting closer to a UbitX once you do that.?
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Re: New "ANTENNAS" group has been formed.
A search within yahoo groups and groups.io for "antennas" finds dozens of such groups.
Also also some in the www.arrl.org forum, and forums.qrz.com forums, among others.
Some with one or two members.
This one has over 4311 members:
? ??
Once this new group has more than a few thousand members I might consider hanging out there.
Though it might be a good place to move discussions in this forum that veer off topic.
Like this discussion.
Jerry, KE7ER
toggle quoted message
Show quoted text
On Fri, Aug 3, 2018 at 06:23 PM, ajparent1/KB1GMX wrote:
I have not found one.
However:
Antennas? on groups IO is officially open.
Allison
?
There's some well established forums out there regarding antennas.
Might be best to just decamp to one of those for things Maxwellian.
I haven't looked them over much, any suggestions of which?
Perhaps a better solution than creating yet another forum.
Some aspects of the EFHW are contentious, and not just here.
But an established antenna forum would have hashed it all out long long ago,
and likely have an FAQ about it.
So they don't have to deal with doing it?again every couple months.
Jerry
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Mike,
You solved the source issue....
with the counterpoise as suggested I did say the SWR will likely change.
Generally the 1:9 scheme is problematic for RF in the shack unless you have
luck or resort to choking...
You might try a End fed half wave as when the wire is tuned you will have less RF.
Also if the bands of interest are the 40/20 there are a few that do them well.
Though a town home is likely a noisy are a for 80/75M.??
However that picture scares me...? ;)
Allison
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Re: Harmonic performance - SSB vs CW
This is primarily an SSB transceiver, and harmonic suppression seems adequate in
that mode on the stock rig.? Best and easiest fix is probably to either not use CW mode,
or do a minor hack to move the CW mixer injection an earlier mixer so the 45mhz
filter takes out the harmonics?as previously stated.
?
The uBitx relay arrangement is not that uncommon, though would be better
to double the relay count and use separate relays for input and output.
Board layout is important.? This guy definitely knows what he is doing:
? ??
Another solution might be to get an outboard set of filters such as the WA2EBY fllter board:
? ??
LPF's such as seen on the uBitx are usually adequate for use with class C amps
on CW transmitters (which are dealing with high power square waves).??
However the uBitx gets by with as few LPF's as possible by covering multiple
bands with each filter.? The corner frequency of the LPF may be a bit high to?
fully suppress the harmonics of the lowest band of that set.
Jerry, KE7ER
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Re: End Fed antennas w/ uBITX
#ubitx
Iz oos,
TLTs can be made with low loss.? ? However making a matched set may be harder
as they have to have the exact same phase response.
Also the 1:9 is 450 ohms? (50*9).
Allison
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Re: None supprest carrier in TX
Make sure you have adjusted the BFO to the correct frequency.? The carrier will drop.
Allison
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Re: Harmonic performance - SSB vs CW
Allison
Have you shared your past findings here? I did a search and found nothing but I could have missed it. It would seem to me that if you knew the product was illegal for use on the air you would have a responsibility to share that with the group.
WA8TOD
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Re: Harmonic performance - SSB vs CW
Warren,
Latching relays have a higher cost, I like the idea though.? However there are lower power
relays that would do the job.? Since the radio eats power on TX anyway another 200ma is tolerable.
I would want band pass before the TX chain.? The logic is you get cleaner out if you put cleaner in
and it wold fix many of the spur issues.? However that's a lot of relays or diode switching for 9 bands.
Allison
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Re: Harmonic performance - SSB vs CW
Arv,
For bitx20 (or 40) a monoband radio traps and Caur filters are a good solution.
For a multi band radio its a spot solution that is likely to case troubles on other bands.
The fundamental issue was inadequate to non existent filtering for the TX path
before the TX.
Allison
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Re: Harmonic performance - SSB vs CW
Warren,
In my testing I also found the isolation across one relay was barely 45db in one configuration and 50 in another.
Using one relay to switch both ends of a filter will compromise the filter attenuation characteristics.
Most other radios commercial put a spdt relay at each end to avoid common mode and coupling.
You are seeing what I saw....
Allison
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Re: Harmonic performance - SSB vs CW
I am not sure Arv. The real solution here is like a "fork lift" upgrade, replacing everything after T11 in the transmit chain. If I were doing a redesign I would use the same four filters, add five more relays, and decode the three lines to get four lines each driving the pair of relays bracketing the desired filter.
?
I would also use latching relays and move the TR switching to the PA side of the filter bank to allow the filters to be utilized on receive as well.
?
All relatively easy to do...... just takes time and money. And motivation.......
WA8TOD
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Re: Harmonic performance - SSB vs CW
Warren WA8TOD
That is interesting, and a bit disturbing as well.? What might be the effect of adding
a series LC trap to ground at the antenna end of the filter, or maybe at the RF PA
end of the filters??
In the now ancient BITX20A Dan Tayloe added a cap in parallel with one of the inductors
in the LPF to form a notch at the 3rd harmonic frequency.? This worked without degrading
performance of the LPF.? However, this current problem seems more complex as it
involves leakage around the filter instead of a simple filter performance issue.
Are you continuing to experiment to find a workable solution that might be applied to the
uBITX?
Arv? K7HKL
_._
On Sat, Aug 4, 2018 at 6:43 AM Warren Allgyer < allgyer@...> wrote: No one is going to want to hear this but the design of the PA output filter is probably fatally flawed and it is likely due to board layout issues.
I have been puzzled how the high order harmonics of 80 meters, for example, could possibly survive a 7th order filter which should have well over 50 dB of attenuation at the 5th harmonic. So today I set out to test the results with a 9th order filter, figuring more is better. The harmonics remained. But in troubleshooting that installation the source of the issue was revealed.
In the attached screenshot the purple trace is the 80 meter CW output with the harmonics clearly far in excess of the green -43 dBc legal threshold. The blue trace is the output with L20 removed which disables the 80 meter filter and blocks RF output from the finals from reaching the output connector. (Don't worry..... the tests were carried out with the drive reduced so the output was only one half watt. And I have a bag of spare IRF510s on hand......). The harmonics remain! How can that be?
Pic #2 shows the path 80 meter RF follows through all three switching relays in order to reach the filter. It is a very novel and inventive concept to use three relays to switch both ends of 4 filters. Most manufacturers would require 8 separate relays to do this job. And for a very good reason.
In order for a filter to provide the required 50+ dB of attenuation, the filter itself must have 60 dB or more of input-to-output isolation. If it does not then the unwanted products simply bypass the filter and go directly to the output. That appears to be exactly what is happening in the filter complex of this unit.
There is no easy fix for this. No amount of on board filtering and tweaking is going to improve harmonic suppression until the path around the filters is blocked. I suspect that path is via the relays themselves but board layout often is critical as well in such cases. My guess is the only solution would be either extensive external filtering or a carefully laid out daughter card to replace the existing filters and relays.
WA8TOD
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Re: Harmonic performance - SSB vs CW
BTW..... in re-reading this, unfortunately after it was posted, I note that my threshold line is set at -53 dBc rather than -43. In your imagination move the green line up one division. It does not change the outcome or the analysis.
WA8TOD
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Re: Harmonic performance - SSB vs CW
No one is going to want to hear this but the design of the PA output filter is probably fatally flawed and it is likely due to board layout issues.
I have been puzzled how the high order harmonics of 80 meters, for example, could possibly survive a 7th order filter which should have well over 50 dB of attenuation at the 5th harmonic. So today I set out to test the results with a 9th order filter, figuring more is better. The harmonics remained. But in troubleshooting that installation the source of the issue was revealed.
In the attached screenshot the purple trace is the 80 meter CW output with the harmonics clearly far in excess of the green -43 dBc legal threshold. The blue trace is the output with L20 removed which disables the 80 meter filter and blocks RF output from the finals from reaching the output connector. (Don't worry..... the tests were carried out with the drive reduced so the output was only one half watt. And I have a bag of spare IRF510s on hand......). The harmonics remain! How can that be?
Pic #2 shows the path 80 meter RF follows through all three switching relays in order to reach the filter. It is a very novel and inventive concept to use three relays to switch both ends of 4 filters. Most manufacturers would require 8 separate relays to do this job. And for a very good reason.
In order for a filter to provide the required 50+ dB of attenuation, the filter itself must have 60 dB or more of input-to-output isolation. If it does not then the unwanted products simply bypass the filter and go directly to the output. That appears to be exactly what is happening in the filter complex of this unit.
There is no easy fix for this. No amount of on board filtering and tweaking is going to improve harmonic suppression until the path around the filters is blocked. I suspect that path is via the relays themselves but board layout often is critical as well in such cases. My guess is the only solution would be either extensive external filtering or a carefully laid out daughter card to replace the existing filters and relays.
WA8TOD
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Raduino Clone kit from W0EB-N5IB
#ubitx
Check my website, for details, but I now have a completely drop-in Raduino clone available in kit form for anyone needing a replacement for a damaged Raduino that they are otherwise unable to repair or just wanting to have a spare on hand.
It's being offered as a bare board, a complete kit of parts INCLUDING the NANO which will be pre-programmed with Ashhar Farhan's latest factory software from Github (Currently v4.3) or , for a slightly higher price, the kit version is being offered with the Si5351 already soldered in place and continuity checked to insure the connections are good and there are no shorts between the pins.
This card has some extra bypassing capacitors, the 4.7K CW pull up resistor can be directly mounted on the board (or if you are replacing an existing Raduino installation and have already wired it to your key jack you can leave it off the board).
The 7805 regulator has been mounted flat on the rear of the board with a heat sink and input dropping resistor so it runs much cooler.? The clone is just over a centimeter wider than an original but the display mounting holes have been kept to the exact same pattern so that a normal 16 X 2 parallel display will mount properly.? The display is not supplied with the kit to keep the cost lower as most users already have one or more on hand anyway,.
The pre-programmed NANO? will be supplied with the pins loose and not installed so the user can mount it either on the front (not recommended) or on the back of the card to keep it out of the way of the display in the manner of the current factory supplied Raduino cards.
Any software that currently runs on an original Raduino will run on this card including the KD8CEC versions.? (That includes CEC's Nextion enabled versions as well).
The construction manual, pictures of the board and ordering/availability information can be found on my website
Jim Sheldon, W0EB
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Hi!
Has anyone one tried MEMS microphone like these..
Replacement elements for mobile phones are available quite cheap. Some variants come with in built compressor and noise cancellation. Found a link with Youtube video looks pretty good...
Rahul VU3WJM
On Saturday, 4 August, 2018, 8:02:07 AM IST, Jack Purdum via Groups.Io <jjpurdum@...> wrote:
Al Peter, AC8GY, who has a lot more assembly skill than I do, made this mic for me using the stock element and switch:
The case is one of those promo pens that had a small LED and battery in it. It really looks nice and is small enough to pack anywhere.
Jack, W8TEE
On Friday, August 3, 2018, 7:58:43 PM EDT, hirosmb <hirosmb@...> wrote:
I used the same stereo connector which is bundled with the uBitX kit, mic+ to pin #1 and switch to pin #2. // hiro, JJ1FXF
2018/08/04 8:11¡¢Eddie Esserman < ee@...&²µ³Ù;¤Î¥á©`¥ë:
Very nice.? Any hint on the connector wiring, please, Vves?
Thanks.
Eddie WA4JXL
sorry for all these posts and questions.
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None supprest carrier in TX
Hi all. I don't know how to suppres great carrier in TX mode.
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Re: 12MHz xtals and QER Filter
Allison,
Here paralleling of cap arose? due to sheer unavailability of good quality caps in pF range in local mkt. I wanted to optimise the filters to best possible extent on local components so that people assembling uBitx in future can do so with whatever in hand or in junk box. It is very helpful to know the impact of such substitutions on filter response.
I did try out some 8 and 10MHz filters based on half bridge lattice following the work of DL6ZB , OM Rolf here:
?
I found them relatively easy to make, matching non critical and impedance's? easily manageable.?
Also found some HC49U 4.43MHz xtals in my old component bin they must be at least 25+ years old from Philips from my post student and struggle days, matched them now? a lot of about 25 xtals and all within 80Hz,? Talk about Quality..!! I made one QER SSB filter its plot is attached. Planning to give a try to some QER filters on 4.915MHz saw a picture on net for an add on board for K2 based on this topology, but I too would prefer xtals in 8-9MHz range with former being more common value.??
As you recommended to avoid ringing sweep rate is kept very slow by keeping the sample rate high on SNA at 1000 samples it sweeps at about 20KHz per minute.?
More as experimentation goes on ...
TNX and 73
Rahul VU3WJM
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Jim Sheldon
George
