Date   
Re: About outta spec signals...

m5fra2@...
 

Thanks Jack, that adds some much needed clarity to the discussion.

 

Colin – M5FRA

 

From: BITX20@groups.io <BITX20@groups.io> On Behalf Of Jack Purdum via Groups.Io
Sent: 09 August 2018 01:15
To: BITX20@groups.io
Subject: [BITX20] About outta spec signals...

 

As most of you know, I'm a champion for good, low-cost, gear for the younger members of our hobby, which is why the recent events leading up to the placement of a warning label on the ubitx.net resource site really bothers me My cohort in crime, Al Peter (AC8GY), and I spent some time today investigating as best we could the harmonics from the µBITX. We do not have lab-grade equipment, but we do have a commercial spectrum analyzer that we used. There are so many parameters that really should be controlled for such measurements, but we can't. In our world, the assumption of ceteris paribus reigns supreme.

Our tests were on a stock µBITX using a 12V supply running into an EFHV antenna. (No, don't even think about it...that can of worms is sealed.) Our tests suggest that the µBITX is about -2dB out of spec on 80M and 40M, but meets spec on the other bands. That's noise level stuff at the margin. We ran the same tests on a $3500+ commercial transceiver and for the bands in question, the µBITX is, worst case, within -4dB or less on all bands. So, am I going to chuck my µBITX and buy a $3500+ commercial rig. Nope...can't afford it. It could be that changes in many factors could work to bring the rig back into spec on the two bands in question. Because the assumption of ceteris paribus really does not apply to all of us, some of us may well be within spec on all bands...who knows.

Al and I are going to follow these tests up later to see if we can detect the harmonics at a distance between our two houses; under 2 miles. I think the FCC's practical worry is that we not generate interference off frequency, thus interrupting someone elses communications. In all practical terms, I don't think this is happening. Has anyone received a notice of same from the FCC?

Jack, W8TEE

Re: Harmonic performance - SSB vs CW

m5fra2@...
 

Thanks Glenn

 

From: BITX20@groups.io <BITX20@groups.io> On Behalf Of Glenn
Sent: 09 August 2018 00:20
To: BITX20@groups.io
Subject: Re: [BITX20] Harmonic performance - SSB vs CW

 

I'm continuing on with my take on the LPF shortcomings. Since others have determined the actual LPF are essentially ok in isolation, I have used the existing scheme but added relays on the ends of each filter. This adds 3 relays to the board.

This may not be the 'ideal' solution but I plan to get a PCB made and see what it does. Initially bench testing. It maintains the existing logic for switching also so no software changes are required in any of the flavours of software available now.

The PCB is designed to fit over the exiting LPF with all of those parts removed and transferred to the new board. A second mounting hole is drilled into the uBITX board for mounting also.   While not ideal mechanically in that I have to remove all of the existing parts, especially the relays will be harder to remove . ( I only have a mechanical sucker and solder wick)

The new pcb has copper pours both sides and extensive vias either side of the tracks etc (195 in total vias)  Obviously this is not a PCB to make at home!   Schematic is attached and some screen shots also for constructive comment.

vk3pe









Re: One question only...

m5fra2@...
 

Alison,

 

And of course any calibration is to manufacturers specs so being precise is always within those boundaries.

 

Colin

 

From: BITX20@groups.io <BITX20@groups.io> On Behalf Of ajparent1/KB1GMX
Sent: 08 August 2018 16:56
To: BITX20@groups.io
Subject: Re: [BITX20] One question only...

 

Colin,

My comments were more global, not in disagreement. 

I do work as a antenna and RF development engineer. mostly research and prototype
development.  So I think after a lot of decades I have a handle on equipment and cals. 
Most calibration is so you can prove the equipment works and for those rare precise
measurements required by spec to be traceable to a known standard even if production
has to tune every one to get it and the application doesn't really need it.

Answer to more than a few significant digits are sometime required 
but when you using reasistors, inductors, and capacitors typically only spec'ed to three
places any more precision is silly and base accuracy of a a few percent is adequate.

Practical knowledge, experience and application says who cares if the filter cutoff
is 5, 897,765.4hz if the real meaningful measure is less than needed attenuation at
third harmonic regardless of the measured value.

Allison

Re: New Warning on uBITx.net

m5fra2@...
 

Exactly!

 

From: BITX20@groups.io <BITX20@groups.io> On Behalf Of Scott McDonald via Groups.Io
Sent: 08 August 2018 12:32
To: BITX20@groups.io
Subject: Re: [BITX20] New Warning on uBITx.net

 

A basic thought could be that a professional radio man would read the statements on Farhan’s website that this is a kit, offered AS IS, not warrantied to any specification, and would not take it on board, eh?

 

The radio and the open collaboration of the people on this reflector to teach others and make it better has been to me one of the most amazing and positive amateur radio experiences I’ve had.  

 

Cheers, Scott KA9P

Make something good happen!


On Aug 8, 2018, at 4:05 AM, Timothy Fidler <engstr@...> wrote:

Boll_ks. there is no fix . there is a maybe fix in the  works. Some people who use or try to  this kit are professional radio men on ships and the like and they don't want their professional blotter compromised by a prosecution from the SMA / FCC and the like .. or even an investigation.  Your statement lacks any level of basic thought IMHO.

Timothy E. Fidler : Engineer BE Mech(1) Auckland , NDT specialist AINDT UT /RT3 , MT2 
Telephone Whangarei   022  691 8405
e: Engstr@...

 


----- Original Message -----

 

To:

<BITX20@groups.io>

Cc:

 

Sent:

Wed, 8 Aug 2018 09:53:37 +0100

Subject:

Re: [BITX20] New Warning on uBITx.net

Bit OTT considering a fix was sorted within a couple of days.

 

 

From: BITX20@groupsio <BITX20@groups.io> On Behalf Of Mike Woods
Sent: 08 August 2018 09:37
To: BITX20@groups.io
Subject: [BITX20] New Warning on uBITx.net

 

I felt that I had no choice but to post a warning for potential uBITx purchasers and existing constructors that there were serious issues with emissions purity.  The following warning now appears on the first (permanently fixed) post:

WARNING:  Issues have been identified recently with the emissions purity of the µBITx.  It is recommended that you study recent posts on this website and avoid operations that could breach emissions requirements.

A reminder that uBITx.net has no association with HF Signals.  It is purely an information site.

I am sorry that the situation has resulted in requiring such a warning.   I have also updated the strengths and weaknesses page with a similar message.

73 Mike ZL1AXG ubitx.net

--
Mike Woods
mhwoods@...

Re: Harmonic performance - SSB vs CW

Henning Weddig
 

Glenn,

one word of caution: I see that You use very broad RF tracks in order to get them as microstrips with 50 ohms impedance. But alongside of these tracks You use only small gaps  (.5 mm ??) to ground. At RF especially on GHz frequencies these small gaps will introduce a capacitive loading, i.e. no 50 ohm microstrip at all! Ok may be for "LF" (30 MHz) may not be an issue.

Why tis word of catuion? Well, a colleague of mine was designing a board  with 50 ohm microstrip tracks surrounded by ground. At 1.3 GHz I had a terrible mismatch which I only could "rectify" after removing some of the surounding ground plane.

Henning

DK5LV 


Am 09.08.2018 um 01:19 schrieb Glenn:

I'm continuing on with my take on the LPF shortcomings. Since others have determined the actual LPF are essentially ok in isolation, I have used the existing scheme but added relays on the ends of each filter. This adds 3 relays to the board.

This may not be the 'ideal' solution but I plan to get a PCB made and see what it does. Initially bench testing. It maintains the existing logic for switching also so no software changes are required in any of the flavours of software available now.

The PCB is designed to fit over the exiting LPF with all of those parts removed and transferred to the new board. A second mounting hole is drilled into the uBITX board for mounting also.   While not ideal mechanically in that I have to remove all of the existing parts, especially the relays will be harder to remove . ( I only have a mechanical sucker and solder wick)

The new pcb has copper pours both sides and extensive vias either side of the tracks etc (195 in total vias)  Obviously this is not a PCB to make at home!   Schematic is attached and some screen shots also for constructive comment.

vk3pe










Re: reverse polarity protection (ubitx.net)

Mike Woods
 

MVS Sarma

Thank you!  I am uploading now.

Mike


On 8/08/18 11:02 PM, Mvs Sarma wrote:
Here is a more meaningful diagram

On Wed, Aug 8, 2018 at 4:17 PM Mvs Sarma <mvssarma@...> wrote:
I got your point Mike
 I shall upload a suitable diagram with jack more understandable.


On Wed, Aug 8, 2018 at 1:17 PM Mike Woods <mhwoods@...> wrote:
MVS Sarma

It is the drawing of the jack that people are referring to, not the positioning of the fuse!
The vertical bar would normally represent the sleeve - and you have this connected to the fuse and on to +12v?   Shouldn't the sleeve and the tip be reversed in the diagram?  Or do you normally have the sleeve positive and the tip negative (some people do - but most don't) in which case the diode is shown incorrectly!

73
Mike

On 8/08/18 12:34 AM, Mvs Sarma wrote:
Sarma surely responds.
 The reverse protection diode has been shown in the ubitx sch , both v3 and v4 perhaps.
 I would only suggest that let us have a fuse in series to dc of say 5 amps. the reverse diode would sit after the fuse to ground.
 Any accidental reverse connection , the fuse would blow and reverse voltage would not continue to the actual circuit, once fuse blows.


Regards
MVS Sarma
 

On Tue, Aug 7, 2018 at 1:56 PM, Mike Woods <mhwoods@...> wrote:
Jonathan

I will add PH2LB's reverse voltage protection solution to that page at your suggestion.  I hadn't noticed that idea previously, but did recognise the distinctive build so I guess it is on ubitx.net somewhere.

I am not sure about the diagram from MVS Sarma.  Let's wait and see whether he responds?   He may care to redraw the diagram if he agrees!  Everybody seems to draw those sockets differently ...

73

Mike ZL1AXG ubitx.net


On 7/08/18 2:58 AM, Jonathan Washington wrote:
Hi there,

In wiring my µBITX based on the guides and notes available at hfsignals.com, ubitx.net, 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 https://ubitx.net/ubitx-fix-reverse-polarity-protection/ 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 https://groups.io/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 µBITX.  In MVS Sarma's solution, my understanding is that only the fuse would blow, and the µBITX 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


--
Mike Woods
mhwoods@...


--
Mike Woods
mhwoods@...


--
Mike Woods
mhwoods@...

Re: New Warning on uBITx.net

Mike Woods
 

Well my ubitx.net warning seems to have generated a few comments ... And I didn't even suggest that people shoudn't buy the µBITx kit!

If you look at the strengths and weaknesses page, there are still almost as many strengths as weaknesses.

I would point out that I have a µBITx and two BITx40's and I have no intention of trashing them.  The BITx40 does not have the problems that the µBITx does with regards to emissions, and the capacitor solution for the BITx40 is fairly easy to effect in dealing with the second harmonic, which is a bit marginal in some rigs.  

I have simply pointed out, using non-emotive language, that the µBITx has issues with spectral purity and that people need to read up on it before they operate the rig.

In fact the µBITx has at least two different known issues with spectral emissions- generated from two different design problems.  People have focussed on the LPFs in the output stage, but the mixer products appear to be as bad or worse on phone above 18MHz than the CW harmonics issues.   The mixer issue  won't be solved by using outboard LPFs.  BPFs or HPFs will need to be series up with LPFs.  BPFs are a bit more tricky to set up and on the output end of the business will probably need larger cores. It seems very unlikely that when multiple people report these issues that the problem is an isolated one affecting only a few units.  We can also observe, again following multiple reports of the problems, that the v4 board seems to have inadequate audio gain and a proportion of constructors (not all) have found that the audio stage causes distortion problems. Fortunately there are easy and low cost ways of fixing the newly introduced issues.

Also, for those of you claiming that mods have already been found for the spectral purity concerns, I would advise you to wait and see.  I would note that both the pop fix and AGC fix took a while to be refined...  And µBITx top boards designed to fix all the short-comings were trumpeted back in January, but have never been heard of again!

If we need to remove components from almost 1/4 of the board's surface area (LPFs and relays) and the 4 toroid 30MHz LPF as well, and substitute two daughter boards - one stuffed with bandpass filters and relays (16 toroids and 20 capacitors), and the other with 4 LPFs (12 toroids, 16 capacitors and 8 relays), then somehow I think only a small proportion of constuctors will deploy these fixes.  For a start that's a lot of parts to buy and find room for off-board.

That leaves many 1000s of pollution generators in people's shacks. 

There are those who have difficulty reading basic circuit diagrams, knowing how to put a fuse in circuit, or sorting out how to load an arduino sketch on their computer ... I am not knocking these folk, just pointing out the facts.  I get a fair few emails from distraught hams too ashamed to admit their mistakes on the list (and who can blame them) - those who hooked up the 12v the wrong way round to the power socket, or who plugged the audio and raduino KF2510 jacks into the wrong socket, who wired up the volume control incorrectly and it seems to no longer work, and those who blew up their raduino by sticking 12v on a pin or shorted out two neighbouring I/O pins, etc. Accidents happen.  It is great that amateur ops are finding out about all this stuff through trial and error, because they are learning the whole time and are not doing it on their $3000 commercial rig. 

But don't tell me that a fix has been found that we can all  implement and simply get on with operating our rigs!  For some of us, moving the parts off the board to another daughter board won't be a big issue.  But for others, finding the money for all those extra parts (probably up to $100 worth of parts in this country), and building those boards will be very difficult indeed.   They need to be warned now that problems have been identified.

For months we have assumed that our rigs were playing nicely with emissions and disposing of the nasties in the LPFs.  Now we find out that this is not  the case.  It doesn't look like the problems are going to be easily solved, and probably not today or tomorrow.  

So putting up a warning message encouraging people to look into the known issues before operating their rig is probably not a bad idea?

I have had an absolute ball building and modding my BITx rigs. I don't intend to stop now.   I am not closing down uBITx.net.  But I am not going to hide my head in the sand and declare that there isn't an issue.  Now, let me look out the BITx40s, because I have some interesting ideas for enhancing these.   It just so happens that a 3.2" Nextion (just off the boat from China and still in customs) is about ready to be installed in one of those BITx40s ...  experimenting continues ... and some coding.

Mike ZL1AXG ubitx.net





--
Mike Woods
mhwoods@...

Re: About outta spec signals... uBitxv4

 

Board No.303/1
Mic In = `100mV
Po = 10W at 7MHz audio drive constant for all bands. Power varies.

Using Narda 30Db atten + Narda adjustable in series.

Only 2 markers, 2nd marker at the NET highest peak.

10M is just under 40db, Rest are as expected.
Emacs!
Emacs!
Emacs!
Emacs!


At 09-08-18, you wrote:
It would be great if more people could run tests on their uBITX transceivers. We seem to have only a few people with spectrum analyzers running test on a small test case of boards. There must be more people with equipment that could run test on a larger sample of radios.

If it turns out there a significant number or transceivers that do meet spec, maybe we could try to figure out why those work. And I agree the margin that the uBITX is out of spec may be in the measurement "noise" figure.

If you look at the spectrum analyzer screenshots the harmonics do not decrease with frequency. Even with no filter the harmonics would decrease with increasing frequency. It would only take a small improvement for the uBITX to be in spec.

Tom, wb6b

Re: Harmonic performance - SSB vs CW

rcbuck@...
 

Jerry,

You are correct. I was looking at Mouser and failed to notice the price was for a qty 500 reel.

Ray,
AB7HE

Re: Good news, bad news

Tom, wb6b
 

Re: Good news, bad news

Tom, wb6b
 

I was googling around some more and it looks like some folks have hacked the DebugWire protocol to create a free Arduino command line debugger.

Tom, wb6b

Re: Help needed with KD8CEC memory manager

a.vision
 

That's exactly what I am getting  I can't understand why any help greatly appreciated thanks .



Sent from my Samsung Galaxy smartphone.

-------- Original message --------
From: Bill <allerthomes@...>
Date: 09/08/2018 04:24 (GMT+00:00)
To: BITX20@groups.io
Subject: Re: [BITX20] Help needed with KD8CEC memory manager

I have gone back to the Hamskey website and tried to follow the directions for the memory manager. My problem right now is that nothing happens when I click "read from ubitx", although I did get it to work at one time, and was able to create a back up file, which I can load into the manager. I have made some changes and hit write to..., after hitting encode. A green bar will slowly run across the screen untill finished. Each time it will show o successful. So it seems I cannot read or write from this program right now. Any thoughts?

BITX40: Qui peut m’aider ? Who can help me ?

f6cxo
 

Bonjour

 

Y at'il des OMs francophones sur la liste

J'ai acheté un BITX40 et je n'en suis pas satisfait, j'ai un tac tac pendant la rotation du bouton Fréquence qui est assez pénible.

Merci de me répondre en direct sur mon adresse : f6cxo@...

 

73 Gégé

 

Re: Harmonic performance - SSB vs CW

Ashhar Farhan
 

The three section 30 MHz filter can incorporate notches for the troublesome spurs and harmonics.

- f

On Thu, Aug 9, 2018 at 11:02 AM, Jerry Gaffke via Groups.Io <jgaffke@...> wrote:
The PX1002 SAW filter (86.85mhz)  is available quantity 1 from Mouser.
At quantity 1 it costs $12, vs $6 at quantity 500.

The PX1004 (82.2mhz)  would work in the uBitx, as noted in post 51172
Cost is $6 at quantity 500, same price as the PX1002.
I don't see anybody selling the PX1004 at less than a full reel of 500.

Jerry


Jerry, KE7ER

On Wed, Aug 8, 2018 at 08:34 PM, <rcbuck@...> wrote:
PX1004 would also work at 1/2 the cost of the PX1002.


Re: Harmonic performance - SSB vs CW

Jerry Gaffke
 

The PX1002 SAW filter (86.85mhz)  is available quantity 1 from Mouser.
At quantity 1 it costs $12, vs $6 at quantity 500.

The PX1004 (82.2mhz)  would work in the uBitx, as noted in post 51172
Cost is $6 at quantity 500, same price as the PX1002.
I don't see anybody selling the PX1004 at less than a full reel of 500.

Jerry


Jerry, KE7ER


On Wed, Aug 8, 2018 at 08:34 PM, <rcbuck@...> wrote:
PX1004 would also work at 1/2 the cost of the PX1002.

Re: About outta spec signals...

Christopher Miller
 

Im going to paraphrase what I said directly to Allison as I didn't get a reply. The way I see it, the problem isn't really able to be noticed unless a person is generally in line of site of a transmitter (objects absorb rf and the emissions are also blocked).

She mentioned the aviation hf and marine bands were at risk.

Well here is the thing, the hf aviation bands are used when an aircraft flys trans ocean. So unless you are off the coast outside the realm of where the FCC can even do anything, as a pilot you are fine. If you are maritime, you are in the oceans or close where guess what the FCC has no rights.

So in the end if no one can detect the issue and the major players aren't under the control of the FCC... uh? Being marginal matters why?

Re: About outta spec signals...

Jerry Gaffke
 

OK, Allison says "We are talking greater than 10DB"
Better make that a 200W rig.


On Wed, Aug 8, 2018 at 08:52 PM, Jerry Gaffke wrote:

On present units it would be best to clean them up, though our power levels are low enough
that they may cause less bother than a 100W rig that does meet spec.

Re: Harmonic performance - SSB vs CW

Jerry Gaffke
 

I have gotten a part to just fall out.

Late 1970's I was working on a new memory mapped video graphics board
(a very very early CGA sort of thing driven by a Z80 that sold for $5000).
The 7489 RAM's used in the colormaps were dropping bits when they got hot.

Got some different ones, we installed those DIP16 parts into a board to test.
I played a heat gun on them to see if they would fail like the old ones.
Worked good, then suddenly, darn, they were failing again!
Looked away from the video screen to see I had melted the solder, the parts had
fallen to the floor.

Jerry



On Wed, Aug 8, 2018 at 07:49 PM, ajparent1/KB1GMX wrote:
Oh,  never ever got a part to just fall out even with the Pace.
Solder has enough surface tension to never get it all as a thin film
will hold a part well.  Either that or SMT parts have to be glued down.

Re: About outta spec signals...

ajparent1/kb1gmx
 

Gordon,

Glad to help.  I doubt anyone else has removed relays on one of these.
I've had to help friends do it because of suspected failed relay.  To not fry
the board its controlled heat and patience. 

Oddly its the third time hat picture was posted to day and I think this is the third thread.

Allison

Re: About outta spec signals...

Jerry Gaffke
 

The regs make it pretty clear, any harmonics or spurs that have more power than 43dB down from the carrier are out of spec.
If you measure exactly -43dB then get a more accurate instrument, I doubt it is exactly -43.0000000000000000000000dB.
I doubt *they* care about exactly, and exactly where *they* would care on a 10W rig I don't know.

If a manufacturer sells 10,000 units and 5 are out of spec, then those 5 are out of spec.
But some of the caps dried out in transit?  Those rigs are still out of spec.
And your graduate level statistics class is not going to do us any good here.   ;-)

Bottom line:  Future uBitx's should meet spec.
On present units it would be best to clean them up, though our power levels are low enough
that they may cause less bother than a 100W rig that does meet spec.
I for one will clean mine up.

Jerry, KE7ER
 


On Wed, Aug 8, 2018 at 08:06 PM, Jack Purdum wrote:
When I hear a target of -43dB, what does that really mean? That number or lower? That number plus or minus 3 sigma? I don't know and probably don't want to find out. Still, within -2dB of the target? I wonder.