Re: Harmonic performance - SSB vs CW
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On Sat, Aug 4, 2018 at 12:22 PM ajparent1/KB1GMX < kb1gmx@...> wrote: Arv,
That was a narrow cut. ;)?
It would be the 1M band based on blade length. It was a
narrowband effort using a .9mm blade.
Its my signal slicer...? !groan!
Allison
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Re: Harmonic performance - SSB vs CW
There is a good example of such an old school preselector on the AA3SJ Progressive Receiver Page, I think originally designed by W3TS (?).
Pretty much exactly as Allison describes, 2 bands, total HF coverage. ?I¡¯ve built a couple that I use for receiver front ends, and other than getting the matching toroids to track and finding a 2 gang tuning cap of 300 of/sec or greater, they are pretty quick and easy to build, especially when compare ty winding 10 bands of toroids.
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On Aug 4, 2018, at 1:19 PM, ajparent1/KB1GMX < kb1gmx@...> wrote: >>>>Has anybody looked at making those multi-band filters into tunable BPF designs?
That would add some more knobs and possible operator errors but it is an?
interesting thought.<<<
Old school:
A pre-selector.? The form for tha tis a double tuned circuit with top coupling between
elements and link coupling to the adjacent 50 ohnm circuits.? ?It would require a
multi-gang capacitor as varicap diodes may be modulated by RF at that level
(testing required) and switching as you would need a few maybe two bands to
do 3-30mhz.? ?At most one knob as the Raduino can do the band select.
Its adjustment would be fairly uncritical as it would be in the RX path poor RX
set the pre-selector.??? However If a real cap is used a dual section of the 30-365
form is the minimum but would cover 3-30 in two bands with switched coils.?
Varicap diodes do not have that tuning range so 3 bands possibly 4 using switched coils.
I tried that for the RX with good result for some of the spurs and out of band signals.
since it was in place of the 30mhz filter it did have significantly less spur output
as it was bandpass.? I put it aside for a later day as it made for space issues in
the desired box.? ?That and suggesting it seemed a big complex mod for most.
Allison
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Re: Harmonic performance - SSB vs CW
Arv,
That was a narrow cut. ;)?
It would be the 1M band based on blade length. It was a
narrowband effort using a .9mm blade.
Its my signal slicer...? !groan!
Allison
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Re: Harmonic performance - SSB vs CW
>>>>Has anybody looked at making those multi-band filters into tunable BPF designs?
That would add some more knobs and possible operator errors but it is an?
interesting thought.<<<
Old school:
A pre-selector.? The form for tha tis a double tuned circuit with top coupling between
elements and link coupling to the adjacent 50 ohnm circuits.? ?It would require a
multi-gang capacitor as varicap diodes may be modulated by RF at that level
(testing required) and switching as you would need a few maybe two bands to
do 3-30mhz.? ?At most one knob as the Raduino can do the band select.
Its adjustment would be fairly uncritical as it would be in the RX path poor RX
set the pre-selector.??? However If a real cap is used a dual section of the 30-365
form is the minimum but would cover 3-30 in two bands with switched coils.?
Varicap diodes do not have that tuning range so 3 bands possibly 4 using switched coils.
I tried that for the RX with good result for some of the spurs and out of band signals.
since it was in place of the 30mhz filter it did have significantly less spur output
as it was bandpass.? I put it aside for a later day as it made for space issues in
the desired box.? ?That and suggesting it seemed a big complex mod for most.
Allison
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Re: Harmonic performance - SSB vs CW
Allison
Attempts at humor rarely work well on-line, but I have to ask...
"What band is your band saw designed for?"!? 8-)
Arv
_._
On Sat, Aug 4, 2018 at 12:02 PM ajparent1/KB1GMX < kb1gmx@...> wrote: Arv,
All the way to the 30mhz filter.? The first step is inset a set of band pass filters.
Basic scheme is make the board linear layout as you want the input as far
as possible from the output with a mix of low pass and band pass filters at
the input and low pass filters at the output.? Revised amp chain would be in
general form similar with better devices (from the Q90 spot to the drivers)
and revised transformers.? ?Two sided but plenty of top and bottom ground
plane well stitched with vias to improve the ground and limit ground loops.?
I took a band saw to mine and basically the rear half is everything TX and
TR switching and the front half is the IF audio and Raduino.? ?I abandoned
the rear half too many issues and too few ways for lack of room to improve it.?
Allison
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Re: Harmonic performance - SSB vs CW
Allison
I was afraid of that.? This daughter board idea is getting larger and larger.
Arv
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On Sat, Aug 4, 2018 at 11:51 AM ajparent1/KB1GMX < kb1gmx@...> wrote: Arv,
All the way to the 30mhz filter.? The first step is inset a set of band pass filters.
Allison
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Re: Harmonic performance - SSB vs CW
Arv,
All the way to the 30mhz filter.? The first step is inset a set of band pass filters.
Basic scheme is make the board linear layout as you want the input as far
as possible from the output with a mix of low pass and band pass filters at
the input and low pass filters at the output.? Revised amp chain would be in
general form similar with better devices (from the Q90 spot to the drivers)
and revised transformers.? ?Two sided but plenty of top and bottom ground
plane well stitched with vias to improve the ground and limit ground loops.?
I took a band saw to mine and basically the rear half is everything TX and
TR switching and the front half is the IF audio and Raduino.? ?I abandoned
the rear half too many issues and too few ways for lack of room to improve it.?
Allison
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Re: Harmonic performance - SSB vs CW
Has anybody looked at making those multi-band filters into tunable BPF designs?
That would add some more knobs and possible operator errors but it is an
interesting thought.
Arv
_._
On Sat, Aug 4, 2018 at 8:40 AM Jerry Gaffke via Groups.Io <jgaffke= [email protected]> wrote: 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: Harmonic performance - SSB vs CW
Alison
Assuming we could build a daughter board that replaced the RF PA section, how far
back in the TX path would we have to tap in to drive this board with a relatively clean
signal?
Arv
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On Sat, Aug 4, 2018 at 8:22 AM ajparent1/KB1GMX < kb1gmx@...> wrote: 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
I will leave the forklift upgrade to Farhan and his elves in India.? Maybe there
will be a MK-II version of the uBITX someday?
I was wondering about the LC traps as a mod for existing uBITX boards.? Also
might be possible to move the whole RF PA section off to a daughter-board so
it could utilize the existing uBITX and have a new PA section with all your
suggestions.
Arv
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On Sat, Aug 4, 2018 at 8:11 AM Warren Allgyer < allgyer@...> wrote: 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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Bitx40v3 CAT Control firmware?
I have a Bitx40v3 that hasnt been getting much use since I got my ubitx.? I have been thinking about using it for digital modes, but before I do, I need to get firmware on it that will support CAT control.
The ideal situation would be if there was firmware to be found that supported CAT on the USB interface the same way as Ian Lee's CEC firmware for the ubitx.? I have poked around and read through a few of the versions on github and havent found it, so....is there a version of Bitx40v3 firmware out there that supports CAT on the USB interface?
I am a programmer, so I COULD hack together something of a mashup of the bitx40 and ubitx (cec) if it came to it, but looking to see if someone has already done so
Thanks!
Sean
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Re: Harmonic performance - SSB vs CW
Warren & All,
Unfortunately the findings of Alison and others are dispersed over
many different titled discussions.
The topic of spurs / spur reduction has being raised just in the
last couple of months in threads:-
Understanding Spurious Emissions
si5351a CLK drive levels in uBITX #ubitx
Spurs for Dummies? #ubitx-help
I've highlighted mainly the gain flattering threads for my own
attention.? [BITX20] RF power chain mods and improvements..?
/g/BITX20/message/54483
but the thread extends many posts before & after.....
Personally I'm a confused, dumb
bystander. trying to get my head around:-
/g/BITX20/message/53210
and
/g/BITX20/message/52826?
/g/BITX20/message/51802
/g/BITX20/message/51645
that need clarification?
There is a statement that Spurs are not an issue below 20mhz as the
filters work for that range.
The problem is trying to operate on 15,12 or 10M at any power level
on SSB.
CW TX is not an issue due to the way the radio operates, the Si5351
does CW transmit. This is fairly unique and provides a clean CW
transmit.
We now acknowledge at-least some units have issues with excessive
spurs when tested on CW on 80Mtrs?
To the
experts
Is the general spur issue likely to affect most units, or is it an
unfortunate result of component tolerances combining the 'wrong
way' and can be dialled out by attention to bias / signal levels??
I used to think it was salvageable with experimentation on my part
retaining it as a multiband design, but with the fresh
findings.....
It's a shame the
uBix is like effected, as the TX spur problems are what
prevented the Minima & HF1 designs making prime time?
Alan
On 04/08/2018 15:28, Warren Allgyer
wrote:
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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
I always use external low pass filters I have done some years ago. They are six according to the frequencies and can be put in series to increase harmonics attenuation. No relays, just plug and play. I know it is a rudimentary solution but I think it solves many issues in homemade stuff.
Il 04/ago/2018 18:51, "Warren Allgyer" < allgyer@...> ha scritto: Correction -- My unit is not illegal on all bands. Spectrum Analyzer output for each band can be found in the Photos section at?/g/BITX20/album?id=65861. Here is the summary:
80 meters - SSB: OK? ?CW: No
60 meters - SSB: No? ?CW: No
40 meters - SSB: No? ?CW: No
30 meters - SSB: No? ?CW: No
20 meters - SSB: OK? ?CW: No
17 meters - SSB: OK? ?CW: OK
15 meters - SSB: OK? ?CW: OK
12 meters - SSB: OK? ?CW: OK
10 meters - SSB: OK? ?CW: OK
These measurements are for a sample of one. All measurements were made at 2 watts for consistency and to avoid any overload or clipping issues. This does not mean YOUR unit is illegal! I have no way of knowing how consistent this problem is...... I suspect it is the same with all units but it is your responsibility to operate legally and there is good reason to believe if you are using one of the "No" modes above, you might be missing that bar.
WA8TOD
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Re: Harmonic performance - SSB vs CW
Jerry,
if you move the keying to the either of the earlier mixers CW becomes a victim of
the Spur issue.
As to the corner frequency the offending harmonics are 2nd, for 3.5 its 7mhz above the 80m filter
and the third which is particularly strong at 10.5mhz well above the 80m filter.? I did sweep mine
and it was not at all bad for a 7 element filter.? However relay blow by does not help.
FYI the EBY filter was revised to improve it but its still a low pass filter.? However if it were between
the first mixer and the power amp it would help greatly up to 20mhz.
When I look back at Warren's SA out put it shows the harmonics I was seeing while testing for improved
flatness whenever I over drove the amp.? Which is why I asked if he tried lowering the drive to see
if the harmonics drop faster than the power.? ?The unmodified amp has a strong tenancy to run out
of power ( current or voltage limiting) in the predrivier and driver stages even at the low end of the
range.? That sweep goes to 30mhz so there are a lot of higher order harmonics and spur products
visible.? ?Even when your seeing 10W at 80M? its hitting the wall at 10.5mhz (third harmonic)
as well as the higher harmonics.
A reminder for those working with linear amps the power out is the total of all the amplified signals
including those stopped by filters.? There are a lot of milliwatts in those harmonics even if they never
get past filters they still help heat the drivers and finals.
Allison
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Re: Harmonic performance - SSB vs CW
Correction -- My unit is not illegal on all bands. Spectrum Analyzer output for each band can be found in the Photos section at?/g/BITX20/album?id=65861. Here is the summary:
80 meters - SSB: OK? ?CW: No
60 meters - SSB: No? ?CW: No
40 meters - SSB: No? ?CW: No
30 meters - SSB: No? ?CW: No
20 meters - SSB: OK? ?CW: No
17 meters - SSB: OK? ?CW: OK
15 meters - SSB: OK? ?CW: OK
12 meters - SSB: OK? ?CW: OK
10 meters - SSB: OK? ?CW: OK
These measurements are for a sample of one. All measurements were made at 2 watts for consistency and to avoid any overload or clipping issues. This does not mean YOUR unit is illegal! I have no way of knowing how consistent this problem is...... I suspect it is the same with all units but it is your responsibility to operate legally and there is good reason to believe if you are using one of the "No" modes above, you might be missing that bar.
WA8TOD
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Re: Harmonic performance - SSB vs CW
Warren,
Not for harmonics.? The spur issue took precedence.
They were shared in other message threads here.
The spur issue was discovered during power amp improvements.
IT was announced here in the forum and also on the ubitx.net site.
IT was why I suggests keying the modulator as then CW cleans up
leaving only the above 20mhz spurs.??
Basically for any band above 20mhz there are spurs below the cutoff of the 10M filter.
Specific example is at 28mhz the spur is 17mhz (+- offsets).? At 21mhz the spurs
are 24mhz (they move up as you move down).? At 14mhz the 20M filter catches any
spurs but not the 30mhz filter.
That is why I said band pass filter before the transmitter would clean up a lot of issues.
Those being harmonics, spurs and some of the oddball mix products visible.
From my point of view my radio is not going to see an antenna other than as RX.
I am looking at how i can make it suitable for use as transceiver.?
Its up to others on this to evaluate the data made available and use or not use.
Allison
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Re: Ubitx will be here tomorrow. Any suggestions for a Bitx newbie
#ubitx
 This picture shows the 2 way pins can be soldered reverse on the nano, i choose the first one (not on the desktop) leaving plastic on the CH340 side, it allow using the nano either normal or reverse side (if you don't leave the plastic this side you cannot use Nano on the normal side), BUT you have to take care to do nice soldering with metal getting inside the holes.
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Hello,
This email message is a notification to let you know that a file has been uploaded to the Files area of the [email protected]
group.
File: ubitx_cat.ino_modified_KD8CEC_F1MQJ.txt
Uploaded By:
f1mqj
Description:
Modified file for v4.3 original firmware (published on may 23) to include communication with KD8CEC memory manager (very usefull for getting/init settings -calibration/BFO). Only lines between KD8CEC F1MQJ comments are modified (0xDB and 0xDC CAT commands).
Modifications are the same than described in KD8CEC http://www.hamskey.com/2018/01/how-to-use-ubitx-manager-for-original.html but adapted to V4.3 original firmware. (remove all text after .ino in your firmware directory -replacing original ubitx_cat.ino). tnx to KD8CEC
Hope this can help - Remi - F1MQJ
Use at your own responsability
You can access this file at the URL:
/g/BITX20/files/ubitx_cat.ino_modified_KD8CEC_F1MQJ.txt
Cheers,
The Groups.io Team
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Hi Eddie,? it is hotmail.com.?? so it is Ian.radio workshop@ hotmail.Co.UK.? Regards. Ian M0IDR
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Ian,
Thanks, I think the usb lead out the back is the plan.? Didn't get the pot pic.? Or haven't found it yet.? Yes, the shaft on Sunil's pot is too small for the knob.? Did you remove his power switch or parallel the two switches?
ee at eddieesserman dot com will work coming this way.? list server doesn't take to email addresses.
Eddie
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Ian,
Thanks, I think the usb lead out the back is the plan.? Didn't get the pot pic.? Or haven't found it yet.? Yes, the shaft on Sunil's pot is too small for the knob.? Did you remove his power switch or parallel the two switches?
ee at eddieesserman dot com will work coming this way.? list server doesn't take to email addresses.
Eddie
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Alan de G1FXB