CW kits are in but in limited supply, I do have more on the way to cover further demand.
?73
??
--
David
?N8DAH
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I don't see a post yet that clearly spells out how to take care of the spurs. This should include pointers to specific parts, show how they get mounted to the board, include fixes for both the 45mhz-DialFreq and the 12mhz spurs. And not be spread across dozens of different posts over the past couple months. There are still questions about the 12mhz spur fix, do Farhan's notes really result in something that resonates at 12mhz?? Is there a way to avoid knocking out 30m? It's easy enough for some of us to get there with the information provided. But I'd say it's not yet clear enough for the majority of uBitx owners. I'm not finding time to do much other than pontificate here myself. And I suppose that means I'm fair game for criticism, so have at it. But creating easy to follow instructions to cure harmonics and spurs is critical here, and I intend to push the issue now and then if it does not get resolved. Once we have complete instructions down that have been properly vetted, it should be possible for everyone to confidently mod their rig for spurs and harmonics. Till then, it will take a spectrum analyzer to verify the fix is correct. Or a day with a step attenuator and a general coverage receiver Looks like HFSignals is still shipping boards with no mods to address harmonics or spurs. ? ?? /g/BITX20/message/62307In message 62308, Raj does say the Axiom relays do address the harmonics if not socketed. He also states:? "The 45MHz filter fix of mine and the LP filter of Farhans does the same thing." I vote for the LP filter, as the extra 45mhz crystal filter is much tougher to obtain than coils and caps, Note that the new crystal filter would have to match the center frequency of the filter at Y1, these filters are often sold in pairs to ensure a match. Jerry, KE7ER . ?
On Wed, Dec 5, 2018 at 07:37 PM, AndyH wrote:
Respectfully, the point of being a ham is to learn about electronics and RF.? The point of the BITX radios is that we have a base radio to mod and explore and learn from/with.? Toroids are really easy to wind - and Farhan's latest mod was developed specifically because there's nothing critical.? It's easy to build, easy to install, and doesn't require a spectrum analyzer to align.
As for the relays:? I'm guessing anyone that can read in any language can pattern match 'Virtual' and "Axicom" and understand that if their radio doesn't have Virtual relays that it's been upgraded.? We've been photographing the boards, comparing schematics, and noting differences since the BITX40s started to ship - we'll know when it's updated (and Farhan's already stated that the relays have been updated).
Questions from folks are good - we should be encouraging them!? Answers from folks that grok more fully is called leadership.? Calling new hams 'clueless' is not useful.
73, Andy, KG5RKP
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Respectfully, the point of being a ham is to learn about electronics and RF.? The point of the BITX radios is that we have a base radio to mod and explore and learn from/with.? Toroids are really easy to wind - and Farhan's latest mod was developed specifically because there's nothing critical.? It's easy to build, easy to install, and doesn't require a spectrum analyzer to align.
As for the relays:? I'm guessing anyone that can read in any language can pattern match 'Virtual' and "Axicom" and understand that if their radio doesn't have Virtual relays that it's been upgraded.? We've been photographing the boards, comparing schematics, and noting differences since the BITX40s started to ship - we'll know when it's updated (and Farhan's already stated that the relays have been updated).
Questions from folks are good - we should be encouraging them!? Answers from folks that grok more fully is called leadership.? Calling new hams 'clueless' is not useful.
73, Andy, KG5RKP
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On Tue, Dec 4, 2018 at 02:39 PM, Jerry Gaffke wrote:
My point is, most readers of the forum have no idea how to proceed. Having three different vaguely described fixes is not quite putting this to bed. We should have a good simple recommeded fix, probably based on Farhan's recommendations in your link:? ? ? /g/BITX20/topic/28088828#61869Should describe exactly what parts are used and show exactly how to install them. Instructions that are complete enough that somebody having trouble relating schematic to board can complete it. And the fix should be verified by somebody with a spectrum analyzer. We have no idea with what mods a uBitx from HFSignals will currently have. Or how to tell a production board with good relays (if such exists) from one with bad relays.? If this does not get nailed down, we will have thousands of posts here from somewhat clueless uBitx owners wondering if they will get thrown in jail for operating their uBitx. (Nobody has yet reported any such trouble.? And there are several thousand unmodded uBitx's out there.) I'd say it's fair enough to call the current situation "absurd". No way to run a railroad, Jerry Andy wrote: >? Farhan has solved the spur problem twice, possibly three times.? >? As it appears to actually have been resolved, and as Farhan has confirmed >? that production is updated? as fixes are identified, >? I'd have to see a board delivered without fixes to agree that it's 'absurd'. Andy, KG5RKP
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Re: Is push pull hf amp has higher spectral purity
I think there was brief mention by somebody in early 2017 about that spur getting transmitted
now that Brian has jogged my memory.?
But mentioned only once more or less in passing, and then it was dropped.??
I think.
But I don't think anybody ever got around to measuring the spur,
Maybe Brian knows more about this.
Possible that the spur strength varies from rig to rig.?
Whatever might effect the strength of the VFO's 4'th harmonic.
I personally don't think it's a significant issue.
And if it were, going to Allard's v2 firmware and mods is a very easy fix.
Jerry
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On Wed, Dec 5, 2018 at 05:36 PM, Guy WB7SZI wrote:
Have you seen QST¡¯s review of the BitX40? Seemed to pass their analysis.?
I think that was with an unmodded radio.?
Guy WB7SZI?
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Re: Is push pull hf amp has higher spectral purity
Have you seen QST¡¯s review of the BitX40? Seemed to pass their analysis.?
I think that was with an unmodded radio.?
Guy WB7SZI?
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Re: LSB signal looking more like AM
Mindlessly twiddling RV1 on the Bitx40 (or RV2 and RV3 on the uBitx) will blow the IRF510's.
I assume you were watching IRF510 drain current when you did the adjustment..
If not:
Power down, turn that pots full clockwise (it's backwards) for minimum drain current. (it's backwards) and minimum drain current.
Carefully adjust that pot for 100ma of quiescent current through the IRF510
as instructed on the HFSignals tuneup page.
Will be nothing at all for about half a revolution, then the adjustment gets kind of touchy.
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On Wed, Dec 5, 2018 at 04:50 PM, <joshuaclough4@...> wrote:
I've tried adjusting the two pots thinking that something was overdriving the signal to create this, but those in any combination don't seem to change the sideband supression (or lack there of).
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Re: Fw: [BITX20] UbitX audio hiss but no rx
Sean
do check to make sure you don't have a short on the antenna connection.? tuning around one or more bands - do you find evidence of signals that you can tune in?? this would be a BFO that is very far off.? note the frequency dial should show a frequency change with tuning - otherwise you have a misconnection between raduino and main board.? do rule out simple issues.?
Curt
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LSB signal looking more like AM
My SDR shows my BITX40 signal looking more like AM. Has the carrier and USB when it should not. The USB does look weaker than the LSB that's actually supposed to be there, but still way too strong.
I've tried adjusting the two pots thinking that something was overdriving the signal to create this, but those in any combination don't seem to change the sideband supression (or lack there of).
I even tried changing the raduino sketch (which being evidently a clone was fun in itself) without any change.
I've previously tested a lot of stuff already on the board because It stopped transmitting before and stuff tested fine, which drove me nuts. Eventually figured out it was the incompatible microphone type I had hooked up. Had simultaneously changed the power supply and thought that had damaged something and never thought about the mic.
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Re: Is push pull hf amp has higher spectral purity
Jerry,
I agree with what you have written and detailed. The transmit spur varies with frequency. Away from 7.2MHz it is outside of the band. Feeding the Raduino into the disabled vfo is not optimal as regards signal purity.
The start of this thread was a suggestion that the Bitx40 might be easier to get fcc compliant. Being single band that might be true but it is not without its own problems. There has been little reported on the Bitx40 since the uBitx was released.
Brian VK4BAP
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Re: FS: SotaBeams Laserbeam DSP Variable Filter
No apology necessary, David. I just need to use my eyes the way they
were meant to be used. Link showed up fine. - Rich
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On 12/4/18, N8DAH <Dherron@...> wrote: Sorry gents should have made the link more obvious. I sold it this afternoon
to a group member
--
David
?N8DAH
Kit-Projects.com ( )
Shop is open! ( Https://Shop.Kit-Projects.com )
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Re: Desoldering tool suggestion
Just took my relays off in 20 minutes using a? ECG J-045-DS Electric Corded De-Soldering Iron, 420 Degree C Tip Temperature, 45W
From Amazon. Didn¡¯t even need to clean the holes
73
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On Dec 5, 2018, at 3:18 PM, bill@... wrote: I've used the GC Electronics 12-2157 desoldering tool for a number of rework jobs, and it's always worked very well. I have not yet desoldered the relays on my v3 uBITX, perhaps this weekend if some time opens up (I have the Axicom relays ready to go).
Bill N2RKL
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Desoldering tool suggestion
I've used the GC Electronics 12-2157 desoldering tool for a number of rework jobs, and it's always worked very well. I have not yet desoldered the relays on my v3 uBITX, perhaps this weekend if some time opens up (I have the Axicom relays ready to go).
Bill N2RKL
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Using a toothpick to open the holes is a great idea.? -- Lee - N9LO? "I Void Warranties"
?
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On Wed, Dec 5, 2018 at 6:42 PM Rob Bleumer < Bleumer@...> wrote: It was a? very easy swap with the relays. They came to me im Europe from Alibaba in 3 weeks 18$ for 10. 5 for my friend. Taking the old ones out with normal solder pump. Just one of the old relays lost a leg. With wooden toothpiks and soldering iron I opend the holes.
Total work 20 minuts for all 5 relays. I' m not a professional.
So just try and do it! It's not so difficult at all.
Rob PA0RBL
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Re: Is push pull hf amp has higher spectral purity
Regarding the Bitx40 spur, I previously wrote:
>? I'd say the best solution is to use Allard's v2 firmware and mods,?
>? stay with a high side VFO up around 19.2mhz instead of down at 4.8mhz.
It's possible that a low pass filter on the VFO is sufficient, allowing through 4.8mhz
but not the harmonic at 19.2 mhz.? However, the diode ring mixer is non-linear,
might somehow recreate that 4'th harmonic for us.
Jerry, KE7ER
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On Wed, Dec 5, 2018 at 09:56 AM, Jerry Gaffke wrote:
There is a way in which the Bitx40 can produce a spur, as Brian reports.
Look over the last few posts in this thread:
? ??/g/BITX20/message/21998
The thread has to do with images received when using a low side VFO on the Bitx40.
Example:??
When receiving 7.1mhz, the VFO is at 12 - 7.1 = 4.9mhz.??
The 4'th harmonic of the VFO is at 4 * 4.9 = 19.6mhz, effectively a high side VFO.
We will receive an image if there is a shortwave broadcaster at 19.6 - 12 = 7.6mhz
Not stated in that particular thread, but this can happen on transmit as well.
When transmitting at 7.1mhz, we will have a faint spur at 7.6mhz.
When transmitting at 7.21mhz, we will have a faint spur at? ? ?4*(12 - 7.21) - 12 = 7.16mhz
Note that this transmitted spur can easily pass through the 7mhz bandpass filter
and the transmit low pass filter..
The only factor that keeps the spur in check is that the 4'th harmonic of the VFO?
is much weaker than the fundamental of the VFO, and this may vary from board to board,
the VFO drive level programmed into the si5351, and how the VFO wires get routed.
The curious thing is that when transmitting at 7.2mhz, the spur is at 7.2 mhz.
The spur is a valid SSB signal, but on the opposite sideband.
So there's a vague connection with the 7.2mhz Bitx40 birdie,
but the math behind the two is quite different.
I'd say the best solution is to use Allard's v2 firmware and mods,?
stay with a high side VFO up around 19.2mhz instead of down at 4.8mhz.
??
As Brian points out, this cures the spur, but when transmitting an LSB signal
we have the not-so-sharp skirt of the 12mhz crystal filter facing the carrier and opposite sideband.
So we will have additional carrier leakage, and the opposite sideband is not suppressed quite as well.
However, that's a perfectly legal signal anywhere AM phone is allowed.
Especially if only transmitting 5 or 10 watts.
I am of the opinion that if transmitting at 5 or 10 watts, the spur with a stock low side VFO
is likely down far enough to be more or less acceptable.??
But to fully meet regulations with a Bitx40, use Allard's v2 firmware and mods, and a high side VFO.
Jerry, KE7ER
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Re: Is push pull hf amp has higher spectral purity
There is a way in which the Bitx40 can produce a spur, as Brian reports. Look over the last few posts in this thread: ? ?? /g/BITX20/message/21998The thread has to do with images received when using a low side VFO on the Bitx40. Example:?? When receiving 7.1mhz, the VFO is at 12 - 7.1 = 4.9mhz.?? The 4'th harmonic of the VFO is at 4 * 4.9 = 19.6mhz, effectively a high side VFO. We will receive an image if there is a shortwave broadcaster at 19.6 - 12 = 7.6mhz Not stated in that particular thread, but this can happen on transmit as well. When transmitting at 7.1mhz, we will have a faint spur at 7.6mhz. When transmitting at 7.21mhz, we will have a faint spur at? ? ?4*(12 - 7.21) - 12 = 7.16mhz Note that this transmitted spur can easily pass through the 7mhz bandpass filter and the transmit low pass filter.. The only factor that keeps the spur in check is that the 4'th harmonic of the VFO? is much weaker than the fundamental of the VFO, and this may vary from board to board, the VFO drive level programmed into the si5351, and how the VFO wires get routed. The curious thing is that when transmitting at 7.2mhz, the spur is at 7.2 mhz. The spur is a valid SSB signal, but on the opposite sideband. So there's a vague connection with the 7.2mhz Bitx40 birdie, but the math behind the two is quite different. I'd say the best solution is to use Allard's v2 firmware and mods,? stay with a high side VFO up around 19.2mhz instead of down at 4.8mhz. ?? As Brian points out, this cures the spur, but when transmitting an LSB signal we have the not-so-sharp skirt of the 12mhz crystal filter facing the carrier and opposite sideband. So we will have additional carrier leakage, and the opposite sideband is not suppressed quite as well. However, that's a perfectly legal signal anywhere AM phone is allowed. Especially if only transmitting 5 or 10 watts. I am of the opinion that if transmitting at 5 or 10 watts, the spur with a stock low side VFO is likely down far enough to be more or less acceptable.?? But to fully meet regulations with a Bitx40, use Allard's v2 firmware and mods, and a high side VFO. Jerry, KE7ER
On Tue, Dec 4, 2018 at 07:36 PM, Jerry Gaffke wrote:
Brian,
So when operating between 7.1 and 7.3 mhz on the Bitx40 we have a transmit spur at 7.2mhz?
That would be weird, especially if the spur didn't move as we tuned across that range.
The receive birdie at 7.2mhz is due to the? 12mhz - 7.2mhz = 4.8mhz low side VFO
having a 5'th harmonic at 5*4.8=24mhz which beats with the second harmonic of the 12mhz BFO.
Anybody see any way that this might go out as a transmit spur?
Has anybody else seen this spur?
Jerry, KE7ER
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?
On Mon, Dec 3, 2018 at 01:23 PM, Brian wrote:
The stock Bitx40 has a problem with the 7.2MHz birdie not only on receive but also it produces a spur on transmit which does not meet fcc spec.
You could use it on 7.1MHz and below or change the vfo to high side and move the carrier oscillator to the other side of the filter (Allard's software). Whether you can do that depends on the xtal filter in your Bitx40. You may get lots of carrier and poor sideband rejection.
The Bitx is a good entry into homebrew. You might get away with using it barefoot but take care if you want to push to higher power.
73 Brian.
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Re: Is push pull hf amp has higher spectral purity
In Europe the birdey on 7.2Mhz is a nice end of band signal?
Rob
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It was a? very easy swap with the relays. They came to me im Europe from Alibaba in 3 weeks 18$ for 10. 5 for my friend. Taking the old ones out with normal solder pump. Just one of the old relays lost a leg. With wooden toothpiks and soldering iron I opend the holes.
Total work 20 minuts for all 5 relays. I' m not a professional.
So just try and do it! It's not so difficult at all.
Rob PA0RBL
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Don't say that John. It was never our intention to spam him. ?Perhaps he is impatient that Ashar Farhan did not reply to his query, but all others. ?After all he is also like all of us. I was dam impatient in my 20s. ? OK , Let him come out of his feelings. ? All the best to his hobby and HAM operations.
Lee, you're spamming the group. Please stop. John K5MO
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Folks As you modify these PCB's to correct spurs and such remember;
Adding new?PCB's and or daughter boards often inject new noise sources. and may disrupt existing signals.? Placement? and integrity of new boards will affect the UBITX.? So approach this effort with care. 73 Bill de kd5yyk
From: Jerry Gaffke via Groups.Io <jgaffke@...>
To: [email protected]
Sent: Tuesday, December 4, 2018 12:04 PM
Subject: Re: [BITX20] Ashhar Farhan #ubitx
Curt wrote >? Do expect you will need some mods to correct spurious - the conservative approach >? seems to be a daughter board hosting an added set of relays, and some additions to the 45 MHz filter. Harmonics could be fixed by an external daughter board with relays and transmit low pass filters, duplicating what KT1,KT2,KT3 and L11 through L22 are supposed to be doing. Some forum members have created circuit boards that they sell as a kit to do this. Alternately, just replace the KT1, KT2, KT3 relays with Axicom relays, This is probably the preferred method for fixing harmonics if you can figure out how to remove the old relays. Harmonics are unwanted transmissions that occur at integer multiples of the desired frequency. Some might use the term "spurs" to refer to harmonics. Most people here use the term "spurs" to refer to any unwanted transmission that is not a harmonic. Spurs?are addressed in this thread of 60+ posts: ? ?? /g/BITX20/message/61645In that first post of the thread, Farhan writes: >? 4. With the relays that are now used for ubitx,? the harmonics at 3.5, 7 and 10 are in under -45 dbc. we don't need the axicom relays.
From that, I assume that a uBitx shipped today from HFSignals has new relays, appropriate for RF switching.
Unfortunately, no mention there of how to determine if your uBitx has old or new relays.?
The relays on my first run v3 board of a year ago are of the "Virtual" brand,
model VRS2H-S-DC12V-C.
I'd guess that if the relays on your rig are some other brand, then you have the new relays.
None of this is really nailed down yet well enough for somebody with a uBitx and DVM
to be sure his rig is legal.?
We need to know:
1)? Exactly which uBitx boards need the relays swapped out to Axicom?
2)? Exactly what parts should we procure for relay replacements and spur filters?
3)? Exactly how should those spur fix parts be installed on the board?? (With photos)
Farhan recommended toroids for the spur filter inductors,
Raj has found that shielded surface mount inductors work.
Cheap standard issue surface mount inductors are apparently not sufficient.
?
Rather absurd that this has not yet all been resolved
to a recommended list of part numbers and step by step procedure for installing them.
It's been months.
Jerry, KE7ER
?
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N8DAH
Lee
bill wright