Date   
Re: One question only...

Tom Cooper
 

I promise to let everyone here know if the FCC informs me of poor harmonic control.  Until then, I will assume that not being heard on any band by a RBN skimmer means that I am not interfering with anyone.  

Perhaps we should worry about how many angels can dance on the head of a pin with a head diameter of .01234455".  

Re: One question only...

Mike Short
 

I have had one of the HFProjects lpf boards, and they are very nice.

--
Mike
AI4NS

Re: One question only...

Gordon Gibby <ggibby@...>
 

Yet another thing to fix, in the long list that Alyson and others have been making.  


On Aug 5, 2018, at 22:10, Glenn <glennp@...> wrote:

There seems to be a rather unfortunate placement of the LPF output from K3, running right back along the common of each LPF switching relay common point. Possibly causing less than optimum LPF responses.?

<uBITX_LPF_RELAYS_BOTTOM.JPG>

Re: One question only...

Glenn
 

There seems to be a rather unfortunate placement of the LPF output from K3, running right back along the common of each LPF switching relay common point. Possibly causing less than optimum LPF responses.?

3,2: Nextion Display

Terence Taylor
 

Is there anyway to logically 'flip' the the orientation of the 3.2" NX4024K032_011 display? I am using the front panel on my EF01 case
(https://www.thingiverse.com/thing:2961880)
and when the Nextion display is oriented properly in the front panel, the display is upside down.

I suppose I could edit the front panel .stl file, just wondering if anyone had and answer.

Re: One question only...

ajparent1/kb1gmx
 

Kees,

Better or more low pass filters do not solve the 10M problem and may reduce
power for the CW problem while making it passible.

There are several band pass filters available including your site when placed before the
amp will clean it up to the limits of the ground loops.

It will need switching for each band.  

Allison

Re: Harmonic performance - SSB vs CW

Warren Allgyer <allgyer@...>
 

Today I attempted to measure the passband of the output filters. In order to do it with minimal intrusion I coupled the tracking generator output to the input of the filter bank with two turns looped through T11. The input to the spectrum analyzer came directly from the antenna connector of the uBitx. I then removed PA power, turned the drive all the way down and keyed the rig to engage the relays. I then offset the nominal reading within the passband to zero so I could get an idea what the baseline attenuation of the filters is after cutoff.

It is a very consistent -20 dB or so for both the 80 and 40 meter filters. What this means is the filter bank only attenuates high order harmonics by that amount. This is clearly the source of the harmonic issue on my unit. If we are getting only 20 dB of rejection from the filter then that means any spur at -23 dBc or higher is going to cause compliance problems.

Screenshot of the 80 meter filter is attached with markers at the 3rd, 5th, and 7th harmonic frequencies.

As an aside but worthy of mention: In response to my similar post about this issue on the uBitx Facebook page one owner claims to have tested his unit, packaged in a metal box, and found no spurious outputs higher than -52 dBc. Testing methodology was not disclosed. The point is, and I want to reinforce it, we need more spectrum analyzer tests of different units in order to be sure this is not an issue isolated to one or a few units. And we need to do this before sending everyone on multiple schemes to fix what is not yet a confirmed general problem in my opinion.

WA8TOD


Re: Harmonic performance - SSB vs CW

ajparent1/kb1gmx
 

Arv,

Its easy to fool one self.  For example a medium high dipole may be heard well at 400 miles but 
not at all 5 miles down the road.   A vertical may work better but what is the take off angle?
An NVIS  antenna may work for below 5mhz but whats the setup.

Been through this all before at 40M 1 KW into a Delta loop I had to be at least
25 miles away to hear it weakly.  Yet he could hear the 100W into a mobile
8ft center loaded whip 5x5.

Not hearing it becomes as much antenna pattern and propagation then.  However
it doesn't mean its not radiated.  

The easy way is put a 50 ohm power attenuator on the matchbox and tune it up and measure that.
Least then you have an accurate idea for that specific setup of how bad someone else is likely
to use a different tuner and get a different result. 

The official test is at the jack if anyone asks the question.  Not what is or is not radiated.
Is it me or are we dancing around the problem to avoid it.

Allison

Re: Harmonic performance - SSB vs CW

Arv Evans
 

Farhan, and others....

It might be interesting to install a full-spectrum receiver at some distance from a
uBITX transceiver and measure the primary versus spurious signals at that location.
This of course would take into account the filtering effect of ATU and antenna
resonances.  This would be a real test of what is being transmitted and what is not.

Arv
_._


On Sat, Aug 4, 2018 at 10:22 PM Ashhar Farhan <farhanbox@...> wrote:
I have been following this thread, I have to add three things here :

1. Unike commercial products where no criticism is encouraged, ubitx is an open source radio, So, Warren, we all do want to hear and correct whatever goes wrong with this design. We all hope it gets bette with time. As Linus Travolds reminds us "Given enough eyeballs, all bugs are shallow".

2. The reason for the convoluted relay system is that we ran out of pins on the Arduino to directly switch the LPFs. Instead, we should use a 1-of-N decoders to drive the relays, increase the number of LPFs to six (from the current count of 4). Bad economics. It will also lead to a differently sized board as it will be difficult to fit two more relays AND decoder onto the same sized board. This will mean putting the people like Sunil out of business until they retool their boxes. 

3. Another possibility is to split up the design into multiple boards. It makes sense for the solder happy hams, it is  nightmare for those who'd rather ragchew and chase dx than get under their race car's hood for months.

Given that there are non-technical considerations and a few thousands of ubitx already in use, we must be careful to not break backward compatibility of these radios. Any sugggestions?

- f

On Sun, Aug 5, 2018 at 8:45 AM, Gordon Gibby <ggibby@...> wrote:

Jerry wrote:

"Looks to me like a good part of the problem is board layout.
Each LPF is fed from a relay, then has a trace from the far side of the LPF
coming back right under the LPF to get back into the other set of relay.contacts."


The photo of a dpdt relay that I enclosed was just the only internal image I could find.   I haven't found one of the actual relays used.

Enclosed is a backlit photo to show theground plane --- which covers just about everything --- and the LONG return trace  from the other end of the filter.

I don't quite know how to "read" the rigol display that Warren put up, but since some of his bands hit the -43 dBm requirement of 97.307(d) (first part):  (d) For transmitters installed after January 1, 2003, the mean power of any spurious emission from a station transmitter or external RF power amplifier transmitting on a frequency below 30 MHz must be at least 43 dB below the mean power of the fundamental emission.​....

then I'm guessing that a few dB more isolation and more bands would "pass".    The return trace comes nicely close to lots of components!   The ground plane is available almost below everything.    drilling through and adding a tin metal shield between the return trace and the remainder of the circuit with a couple of solders to the ground plane might add some dB of isolationwithout having to tear into the relay.   It is probably advisable to run the "shield" tin metal right up to the relay in hopes of possibly even improving by a tiny bit the isolation there.   dunno.   brighter people than me, and those with the nice spectrum anallyzers (or Ashar) might have to figure this one out!

cheers,

gordon





From: BITX20@groups.io <BITX20@groups.io> on behalf of Jerry Gaffke via Groups.Io <jgaffke=yahoo.com@groups.io>
Sent: Saturday, August 4, 2018 10:07 PM
To: BITX20@groups.io
Subject: Re: [BITX20] Harmonic performance - SSB vs CW
 
Looks to me like a good part of the problem is board layout.
Each LPF is fed from a relay, then has a trace from the far side of the LPF
coming back right under the LPF to get back into the other set of relay.contacts.

One possible solution:
Rip out that return trace on each of the LPF's.
Add a set of straps at the far end of the LPF's to select one of them for connection to the antenna jack.

I haven't been following closely, has anyone reported any numbers on just how bad
these harmonics are during SSB ops?   

Jerry


On Sat, Aug 4, 2018 at 06:28 PM, ajparent1/KB1GMX wrote:
Using two of the current ones would yield a very good result as on would be literally physically
on the other side of the filter for a good layout.


Re: One question only...

n2vdy
 

Can't speak about all the Russians on eBay but after seeing some stuff there I ended up buying from https://www.rv3yf.store and got everything I expected to get.

One thing to note. The filter kits I bought don't use toroids for the coils. They use slug tuned coil forms.

On Sun, Aug 5, 2018 at 09:22 PM, Timothy Fidler wrote


There are plenty of "maybe dodgy" Russkies etc on Ebay offering stuff but whether it turns up once you have paid ?? 

Re: One question only...

Kees T
 

QRP Labs offers some nice LPF filter kits (good for up to 10W) for all the bands for $4.60 each. Sounds like an excellent solution to me. Go Hans !

73 Kees K5BCQ

Re: One question only...

Timothy Fidler
 

Kees et al  - Virgil at "HF projects for radio amateurs" in the Old Glory has a relay switched filter board rated 100W for $90 as a kit.  V used to offer a 50W compact filter with a rotary switch .. possibly still has the PCBs for it.

Fred at Far circuits can sell you the PCB for the filter from the Kossor 40W HF amp for $11 but with no other parts. Diz, AKA  the toroid king in FL can make up the difference  (Fred is pretty flexible and not US amateurs may  be able to get him to ship the PCB to Diz and then Diz ships the whole works including Silver mica caps to you ).  Fred May be able to sell you the rotary switch . If you want relay control you would have to build a daughter board to interface to the switch wire in points .

Fred also sells the 200W LPF filter board from the Sabin amp. That uses switched relays from a jejeune cct. Ie rotary switch switching one in at time.. There No default relay set ie if the switch is parked then the Tx sees an open cct. He has the relays to suit.  He can send you out an excel spreadsheet of the LPF component settings.

There are plenty of "maybe dodgy" Russkies etc on Ebay offering stuff but whether it turns up once you have paid ?? 

Baruch Z, RF engineer in Israel may offer LPF sets to go with his super high power amps. (as in 2.2kW RF out S/state) . He does not seem to advertise them separately.  https://www.ebay.com/str/4z4rb/   ie. what is inside those fully made up amp cabinets ??  But these Filter sets are of course overkill for the task at hand if they can be had.

Re: Harmonic performance - SSB vs CW

ohwenzelph
 

Pretty much all the Nano pins that go to the external Raduino connectors 
could have a series 1k resistor and still function perfectly well...
Even 100 ohms could be enough to prevent damage.”
”pretty much all” says that some would not, so, which ones would not?
thanks,
-also Jerry

Re: One question only...

Arv Evans
 

Jerry

A several months ago I purchased one of the Blue Pill boards but it is just sitting
here on the workbench waiting for a suitable project.  It does look nice though.

Arv
_._


On Sun, Aug 5, 2018 at 3:05 PM Jerry Gaffke via Groups.Io <jgaffke=yahoo.com@groups.io> wrote:
Hmm,  
Any tone from the second harmonic would move twice as fast as the fundamental.
And 3x for the third harmonic etc.
So distinguishing that stuff in software, we might get by without that 86.85mhz IF filter.
And no front end LC.

So same as your schematic, but a $2 Blue Pill ARM board for the processor?
Something with a 16 bit ADC to listen to the audio with?

Jerry


On Sun, Aug 5, 2018 at 01:29 PM, Jerry Gaffke wrote:
Of course, my suggestions make it not so simple.
And somehow anything capable of phase noise measurements
must also deal with a very powerful carrier, not trivial.

On Sun, Aug 5, 2018 at 01:19 PM, Jerry Gaffke wrote:
Arv,

I like it, nice and simple.

I'd consider a 50mhz LPF up front, another mixer, mmic amp, and one of these 86.85mhz SAW filters:
    https://wireless.murata.com/RFM/data/px1002.pdf
Then no worries about those harmonics.

Fully analyzing the audio tones using an FFT on an ARM processor should give
sufficient resolution for stuff like evaluating phase noise.

The simple direct conversion mixer means you get both sidebands.
But that software on the ARM could figure out which audio tones go up and which go down
as your VFO moves, and thus separate out high from low sidebands.

I've been thinking of building something like this for a couple years,
have not yet tried.
 
Jerry, KE7ER

Re: BITX QSO Afternoon/Evening, Sunday, August 5, 3PM & 7PM Local Time, 7277 kHz in North America, 7177 kHz elsewhere.

Denis
 

Dan,

I copied you here in Murray, Ky. I scanned 40M and there wasn't many signals. Not good conditions tonight. Will try next Sunday.

73

Denis, WB8SKP


On 8/5/2018 6:50 PM, Daniel Conklin wrote:
Just had a complete QSO with Rick, KN4AIE in Sale Creek, TN on 7.277 MHZ. 53-57 with lots of QSB. - 647.7 mi.
1940hrs. EST.
Dan, W2DLC

Re: BITX QSO Afternoon/Evening, Sunday, August 5, 3PM & 7PM Local Time, 7277 kHz in North America, 7177 kHz elsewhere.

Doug W
 

On Sun, Aug 5, 2018 at 06:52 PM, Doug W wrote:
20m seems to be much cleaner by me.  I am going to be working FT8 calling CQ BX AC9RZ EN52 on 14.074 for a little while.
No luck.  I am lighting up pskreporter but hitting the coasts better than the middle.  Did have one person politely message me on JTAlert asking what BX was at least!
 
--
www.bitxmap.com

Re: BITX QSO Afternoon/Evening, Sunday, August 5, 3PM & 7PM Local Time, 7277 kHz in North America, 7177 kHz elsewhere.

Doug W
 

20m seems to be much cleaner by me.  I am going to be working FT8 calling CQ BX AC9RZ EN52 on 14.074 for a little while.  Hope to screech at you.
--
www.bitxmap.com

Re: BITX QSO Afternoon/Evening, Sunday, August 5, 3PM & 7PM Local Time, 7277 kHz in North America, 7177 kHz elsewhere.

Daniel Conklin <danconklin2@...>
 

Just had a complete QSO with Rick, KN4AIE in Sale Creek, TN on 7.277 MHZ. 53-57 with lots of QSB. - 647.7 mi.
1940hrs. EST.
Dan, W2DLC

Re: BITX QSO Afternoon/Evening, Sunday, August 5, 3PM & 7PM Local Time, 7277 kHz in North America, 7177 kHz elsewhere.

John P
 

On Sun, Aug 5, 2018 at 07:16 PM, John P wrote:
Nothing heard on 7277. I'm going to try FT8. I'll call "CQ BX".
Well, so much for that idea! See you all next week!
 
--
John - WA2FZW

Re: One question only...

Kees T
 

Good "One Question Only..." question you asked,  Brian L. Davis.

73 Kees K5BCQ