Date   
Re: Stone Soup

Lev
 

On Wed, 05 Sep 2018 09:55:42 -0700
"Jerry Gaffke via Groups.Io" <jgaffke=yahoo.com@groups.io> wrote:

Nothing logical about building a new one-off homebrew HF transceiver.
But it can be fun!

None of these are necessarily bad ideas, but here's my yeah-but's:
:-)

1. Tuned IFs
Both IF's are tuned by crystal filters already.
Yes, but if we didn't amplify unwanted signals, the XTAL filter has easier task. :-)

2. Filter the output of the LOs
Diode ring mixers are commutating switches, not exactly the same as the
true multipliers of a Gilbert cell. So work best with a square wave as
the local oscillator, not a sine wave. We could use higher levels at the
local oscillator port of the mixers, perhaps just need changes to those
resistors. 
Okay, but the harmonics can cause unwanted products.

3. Push-pull preamplifier ( https://www.sv1afn.com/j310preamp.html )

More gain in front of the first serious crystal filter on RX is not
necessarily a good thing for a wideband HF receiver, just makes it
easier to overload on some local AM broadcast transmitter.

4. RF transistors (BFS17P)
Yes, we could use something better than 2n3904's in places.
Though using buckets of $0.02 2n3904's/mmbt3904's (at lower gain where
appropriate) has a cost and stocking advantage.
I guess the BFS17P is also cheep... but whatever.

5. PA redesign (normal push pull design, two stage of IRF530 ) use
BFQ19S for drivers I plan to look very hard at the G0UPL linear, sounds
like it will be clean and flat and robust and cheap.

6. More filters on the output

If we're talking transmit LPF's, the only failing on the uBitx is
routing there, not the filters themselves.
Ok.

7. Maybe change of the mixers to JFET mixers
Perhaps, but what are we trying to solve?
To be honest, nothing! I just want to build a JFET based mixer. You can
balance JFET based mixer easily. Or we shall use DBMs.

Raj's result suggests the spurs are not caused by the mixers, but rather
by harmonics entering the mixers also stuff getting coupled into the IF
amps from the nearby power amp due to board layout.
Okay. So that is why we shall filter the signals of the LOs.


73s de HA5OGL

--
Levente Kovacs
Senior Electronic Engineer

W: http://levente.logonex.eu

Re: Right-sided relay harmonic attempted fix for v3/4 ubitx

Kees T
 

By the way....those blue butterfly "Non Machinable" $0.72 stamps, while no upside down Jenny airmail stamp, say Non Machin..e..able". 

73 Kees K5BCQ 

Re: Personal Best Distance, SSB Phone #ubitx

 

Don:

Your AGC circuit calls for RF-out to go to K1 pin 12, and RF-in to K3 pin 14. I have scanned the version 4 schematic, and I cannot find anything labeled as K1 or K3. I could guess, but I don’t want to make a mistake and cause any damage. Can you please clarify?

David A Posthuma, WD8PUO

1 (616) 283-7703

 

From: BITX20@groups.io <BITX20@groups.io> On Behalf Of Don, ND6T via Groups.Io
Sent: Thursday, August 30, 2018 11:53 AM
To: BITX20@groups.io
Subject: Re: [BITX20] Personal Best Distance, SSB Phone #ubitx

 

First SSB contact with new uBITX was with JE6EHP on 20m with an end-fed random wire. Nice long chat. Well over 8,000 Km. -Don

Re: Right-sided relay harmonic attempted fix for v3/4 ubitx

Gordon Gibby <ggibby@...>
 

​Oh my!!!!  Kees....ya wanna take over this one??????


I ordered 25 more boards.   Apparently their 10-board price is a very nice one....to do anywhere close to that I had to jump up to 25 board, but probaby eventually that many will wish to work on the harmonics.    Or else someone will have an even better solution.   I just wanted the LEAST WORK POSSIBLE.


cheers!

gordon



From: BITX20@groups.io <BITX20@groups.io> on behalf of Kees T <windy10605@...>
Sent: Wednesday, September 5, 2018 2:04 PM
To: BITX20@groups.io
Subject: Re: [BITX20] Right-sided relay harmonic attempted fix for v3/4 ubitx
 
Gordon,

I think that's great (especially if the 45MHz spur problem is fixed by Raj) and I figured you would sell out quickly. Those "non machinable" stamps worked out well. Just beware.....it can REALLY take off due to the uBITX popularity and I sold 896 of those AGC and Click kits before I called it quits. 

73 Kees K5BCQ

Re: Stone Soup

ajparent1/kb1gmx
 

On Wed, Sep 5, 2018 at 11:09 AM, Lev likely copied:

4. RF transistors (BFS17P)
Yes, we could use something better than 2n3904's in places.
Though using buckets of $0.02 2n3904's/mmbt3904's (at lower gain where
appropriate) has a cost and stocking advantage.

If used right but they are not good at high currents.

The BFS17P  is a really weak device.  Max collector current of 25ma,
FT of 1.4ghz, 15V mac collector voltage.  Good enough for q90 only!

I suspect very few have an idea of how amplifiers in RF power chains work.

What missed is RF from the power amp has a path into the IF and that should
not be so tuned or filters are a bandaid.

If it were simple...

Allison

Re: Right-sided relay harmonic attempted fix for v3/4 ubitx

Kees T
 

Gordon,

Noooooooo !!!........  I think it's great to SHARE the fun of providing partial kits.

73 Kees K5BCQ

Re: W0EB/W2CTX Firmware Source Code Sketches #ubitx

Jim Sheldon
 

Try the full url.  http://www.w0eb.com and see if that doesn't work.  

Jim

Re: W0EB/W2CTX Firmware Source Code Sketches #ubitx

Dr. Flywheel
 

Thanks Jim. This one worked... :)

--Ron    N7FTZ

On Wed, Sep 5, 2018 at 11:26 AM Jim Sheldon <w0eb@...> wrote:
Try the full url.  http://www.w0eb.com and see if that doesn't work.  

Jim

Re: Personal Best Distance, SSB Phone #ubitx

ajparent1/kb1gmx
 

David,

I pulled a copy of the V4 schematic and guess what.  They are marked, and at the bottom
of the page and K1 is extreme left and k3 is extreme right.  So no need to guess.

K3 is next to the antenna connector and it says so right next to it. The writing is
between the relay and the antenna pin plug.

K1 is on the opposing side next to the power connector and it is also labeled!

I wear glasses to read (+1.6) and if I can see that without them then one hasn't looked closely.

Allison

Re: Personal Best Distance, SSB Phone #ubitx

ajparent1/kb1gmx
 

David, by the way the topic is  "Personal Best Distance, SSB Phone #ubitx"

Why did you post about not finding things about the schematic here???????

Allison

Re: Stone Soup

Jerry Gaffke
 

Lev,

> Yes, but if we didn't amplify unwanted signals, the XTAL filter has easier task. :-)

Raj is suggesting a crystal filter to fix our transmit spurs, right up front after the first mixer, before any rx amp.
Doesn't get much more filtered than that.

> Okay, but the harmonics can cause unwanted products.

The design is blocked out such that the primary unwanted mixer products are much higher in frequency,
and easily filtered.  We've been having trouble with unwanted products that are low in frequency,
but Raj's extra crystal filter may have nailed all of that.


> To be honest, nothing! I just want to build a JFET based mixer. 
A perfectly acceptable answer!

>> Raj's result suggests the spurs are not caused by the mixers, but rather
>> by harmonics entering the mixers also stuff getting coupled into the IF
>> amps from the nearby power amp due to board layout.
> Okay. So that is why we shall filter the signals of the LOs.

I believe we're best off leaving the LO's as a square wave so the diode rings
switch as quickly as possible.
Though there are lots of unexpected things going on around those mixers,
and you are more than welcome to experiment with additional filters.
For example, perhaps a harmonic of the 12mhz clk0 BFO is creating havoc
in some other part of the radio due to layout issues and lack of shielding.
That might be fixed by adding a 12mhz bandpass filter on the raduino board.
But I think clk1 and clk2 are both high enough in frequency to not cause that kind of trouble.

The harmonics that Raj fixed are of the 45mhz IF signal itself, not harmonics of the clk2 LO.
where 2*45mhz mixes with the vfo  going into that mixer is the  45mhz-DialFreq spur that Allison found. 
Note that   vfo = 45mhz + DialFreq,   so   2*45mhz - (45mhz+DialFreq) = 45mhz-DialFreq.

The other crud in Warren's plots is low frequency rumble from parts of the power amp
coupling into the IF and then going into the first mixer, but Raj's extra filter also fixes this.

Jerry, KE7ER



On Wed, Sep 5, 2018 at 11:09 AM, Lev wrote:
On Wed, 05 Sep 2018 09:55:42 -0700
"Jerry Gaffke via Groups.Io" <jgaffke@...> wrote:
Nothing logical about building a new one-off homebrew HF transceiver.
But it can be fun!

None of these are necessarily bad ideas, but here's my yeah-but's:
:-)

1. Tuned IFs
Both IF's are tuned by crystal filters already.
Yes, but if we didn't amplify unwanted signals, the XTAL filter has easier task. :-)

2. Filter the output of the LOs
Diode ring mixers are commutating switches, not exactly the same as the
true multipliers of a Gilbert cell. So work best with a square wave as
the local oscillator, not a sine wave. We could use higher levels at the
local oscillator port of the mixers, perhaps just need changes to those
resistors. 
Okay, but the harmonics can cause unwanted products.

3. Push-pull preamplifier ( https://www.sv1afn.com/j310preamp.html )

More gain in front of the first serious crystal filter on RX is not
necessarily a good thing for a wideband HF receiver, just makes it
easier to overload on some local AM broadcast transmitter.

4. RF transistors (BFS17P)
Yes, we could use something better than 2n3904's in places.
Though using buckets of $0.02 2n3904's/mmbt3904's (at lower gain where
appropriate) has a cost and stocking advantage.
I guess the BFS17P is also cheep... but whatever.

5. PA redesign (normal push pull design, two stage of IRF530 ) use
BFQ19S for drivers I plan to look very hard at the G0UPL linear, sounds
like it will be clean and flat and robust and cheap.

6. More filters on the output

If we're talking transmit LPF's, the only failing on the uBitx is
routing there, not the filters themselves.
Ok.

7. Maybe change of the mixers to JFET mixers
Perhaps, but what are we trying to solve?
To be honest, nothing! I just want to build a JFET based mixer. You can
balance JFET based mixer easily. Or we shall use DBMs.

Raj's result suggests the spurs are not caused by the mixers, but rather
by harmonics entering the mixers also stuff getting coupled into the IF
amps from the nearby power amp due to board layout.
Okay. So that is why we shall filter the signals of the LOs.


73s de HA5OGL

Re: Stone Soup

Robert D. Bowers
 

True, and any radio can be improved.  I've done it... reduced the noise floor in one by using shottky diodes for instance - noticeable reduction in the background static (way better SNR) - in an old Galaxy I used to have.  I used to mess around with stuff like that all the time.


I rather cringed when I learned that there is no ALC in the uBITX radio (at least, I think none) - I've seen too many CBs with the alc diode hacked out - and with it gone, the radios splattered something fierce - even shut down a police repeater in town one evening, 'way back when' (I was out trying to locate the culprit with a loop, like others in the area).  The jackass was splattering all the way up to the input of a UHF repeater! 


If I got one of the uBITX radios, that would be the very  first mod I'd make - adding ALC.


Another radio story (true) about ALC - In 1980 I even was (via radio) unable to help prevent a death because of the lack of ALC in a radio (cut diode).  A CB'er was blathering away on Channel (as I remember) 14... and his splatter was destroying communications from above 19 down to 8 or lower.  I was part of REACT back then, and we'd heard a call (via some form of 'skip') that a young girl had been badly bitten by a rattlesnake and they needed help getting out of the back country (a state park) where they were at and needed an ambulance to get her ASAP.  We tried to talk to the CBer and get him to move up or cut back so we could hear, but he went ballistic and ranted about having a right to talk wherever and however he wanted and how dare we interrupt his 'conversation' - and we never found out where they (the girl's family) were at because of splatter.  It was frustrating because we could hear her dad crying for help, but couldn't understand him.


The next day one of my friends called me and said that the girl died, because they couldn't get help to her or get her out in time (thanks to the motormouth with cut ALC).  I don't remember the state or park now (in a different state), but it was a good lesson in what NOT to do and what the consequences could be - for others.


Those are two classic cases why ALC is much more than a good idea, and why "more talk power" is NOT always a good idea.


Anyway,


Lakeland is halfway between Tampa and Orlando, in Polk county.  It's always had a bit of a reputation... if you know what I mean.  I came here with my folks as a kid, and we now dream of escaping someday.



On 09/04/2018 05:01 PM, Gordon Gibby wrote:

​Robert -- i see that you are in Lakeland.   Isn't that somewhat in Sumter county?   I thik there are a bunch of folks into emergency ham radio commuications down there.   Anyway, that Alnico HF radio looks pretty good!!   I hadn't heard of it but one of my friends has an Alnico for HF and he is happy with it.


Yes, I think while we want to get correct information out there, different societies may have different "baselines" for what they consider "good" or "poor" and it doesn't do a lot of good to criticize some one elses radio or work..   Rather, the more useful parts of this group have been the identification of problems and then the IMPROVEMENT of those problems.   I've learned a lot, but I think some people don't grasp how their words can wound.   In print it is difficult to judge the heart of the person making the keystrokes. 


Keep up the good work!!!    Ham radio has a zillion different facets and not all of them will appeal to everyone, but we all may find something interesting next year, that we didn't, THIS year.


cheers,

gordon


Re: W0EB/W2CTX Firmware Source Code Sketches #ubitx

MadRadioModder
 

I concur. 

MRM

 


On Sep 5, 2018, at 1:16 PM, Dr. Flywheel <Dr.Flywheel@...> wrote:

Excellent choice about releasing the source code to the public domain. This is keeping with the true spirit of "open source" and open contribution sharing.

The caveat -- I am getting "404 page not found" upon clicking on the link in your email message.

--Ron    N7FTZ 

On Wed, Sep 5, 2018 at 9:06 AM Jim Sheldon <w0eb@...> wrote:
Due to the fact many people were having a bit of a problem compiling some program sketches after the TSW group changed over to using the Teensy 3.6 for the MPU, we chose to publicly release only the HEX files for each subsequent release. The source code was still available to anyone on request with the caveat that if you modify it, you are on your own (still applies here as well) as we can't know your hardware configuration and don't really have the time to go through your source code as well as ours to see what you did. If it doesn't work when you modify it, you will have to figure out why and fix it yourself. All our source code is well documented and commented to the point the routines should be easily understood by anyone familiar with the C language and the Arduino/Teensy programming IDE's capabilities.
 
Today we decided that providing the source code only on request wasn't really in keeping with the true "Open Source" concept of software and so the source code files to all of our recent and ongoing uBITX software will now be in an openly available "Latest Source Code sketches" directory in the "Files" section of the TSW website (www.w0eb.com)
 
Feel free to download and try any of them. All the programs are complete with PDF files containing the necessary instructions for use (and wiring mods if they are needed).
 
Also, because of the necessary modifications to the Arduino's "TeensyDuino" portion of the IDE to allow our Teensy 3.6 based versions to be compiled, please read the following carefully. This information is also contained on the main page of the www.w0eb.com website and again in the MANDATORY LIBRARIES directory in the "Files" section of the webpage as a README file.
_________________________________________________________________
 
Because we moved the I2C bus from "Wire" (SDA0/SCL0) to "Wire2" (SDA2/SCL2) on the Teensy for more efficient circuit board trace routing on our Teensy 3.6 based "BITeensio" card, more than a few programming headaches were encountered. It appears that nobody has an I2C library for the displays that uses other than SDA0/SCL0 since the Arduino family only has one I2C port. The Teensy 3.6 has four I2C ports but the currently available libraries don't have the other ports (Wire 1,2 and 3) well defined. This makes it difficult to use anything other than "Wire" (SDA0/SCL0) to communicate with and control the Si5351 clock chip and the I2C display(s). (Yes,multiple displays ARE possible.)
 
Since we were already committed to using "Wire2" for all the I2C stuff (Si5351 clock and the displays), our chief programmer W2CTX bravely undertook the monumental task of re-writing one of the libraries to make it all work. We are happy to report that went well and software compiled for the BITeensio is working nicely with the new hardware.
 
The reworked library is now available in the "MANDATORY_LIBRARIES" directory of this website and in order to use it, the Arduino IDE (with "Teensyduino" additions) will have to be modified a bit to keep things compatible.
 
First, you have to remove the library named "Wire" from the Arduino/hardware/Teensy/avr/libraries directory. Next, run the IDE and under the "Sketch" pull down menu, click on "Include Library" and then under the list that opens, click on "Add ZIP Library". Point it to where you have the "Newliquidcrystal_Wire2_1.3.5.zip" file saved, select that file and click "Open". The new library will be saved to the proper place.
 
In order for this library to work properly the "Wire" library in the Teensy's hardware libraries directory (see above) MUST be deleted. Don't delete the one in the "Arduino" hardware libraries directory though or you won't be able to compile a lot of Arduino programs. (This "How to use the library" information has been included in the MANDATORY_LIBRARIES directory as a "README" file.)
 
Jim Sheldon
for the TSW team
09/05/2018


--

…_. _._

Re: Stone Soup

MadRadioModder
 

One off?  Why would i announce a one off project here?  A group project is another thing. And of interest. 


MRM

 


On Sep 5, 2018, at 12:55 PM, Jerry Gaffke via Groups.Io <jgaffke@...> wrote:

 

Nothing logical about building a new one-off homebrew HF transceiver.
But it can be fun!

None of these are necessarily bad ideas, but here's my yeah-but's:

> 1. Tuned IFs
Both IF's are tuned by crystal filters already.

> 2. Filter the output of the LOs

Diode ring mixers are commutating switches, not exactly the same as the true multipliers of a Gilbert cell.
So work best with a square wave as the local oscillator, not a sine wave.
We could use higher levels at the local oscillator port of the mixers, perhaps just need changes to those resistors. 

3. Push-pull preamplifier (https://www.sv1afn.com/j310preamp.html)

More gain in front of the first serious crystal filter on RX is not necessarily a good thing
for a wideband HF receiver, just makes it easier to overload on some local AM broadcast transmitter.

4. RF transistors (BFS17P)
Yes, we could use something better than 2n3904's in places.
Though using buckets of $0.02 2n3904's/mmbt3904's (at lower gain where appropriate) has a cost and stocking advantage.

5. PA redesign (normal push pull design, two stage of IRF530 ) use BFQ19S for drivers
I plan to look very hard at the G0UPL linear, sounds like it will be clean and flat and robust and cheap.

6. More filters on the output

If we're talking transmit LPF's, the only failing on the uBitx is routing there, not the filters themselves.

7. Maybe change of the mixers to JFET mixers
Perhaps, but what are we trying to solve?
Raj's result suggests the spurs are not caused by the mixers, but rather by harmonics entering the mixers
also stuff getting coupled into the IF amps from the nearby power amp due to board layout. 

Jerry, KE7ER



On Wed, Sep 5, 2018 at 09:12 AM, MadRadioModder wrote:

Don’t be so obvious and logical with this group!

 

 

toggle quoted message. . .

 

From: BITX20@groups.io [mailto:BITX20@groups.io] On Behalf Of Lev
Sent: Wednesday, September 5, 2018 8:00 AM
To: BITX20@groups.io
Subject: Re: [BITX20] Stone Soup

 

So why don't we create a new design? Slightly more expensive, but a good one. My thoughts:

1. Tuned IFs

2. Filter the output of the LOs

3. Push-pull preamplifier (https://www.sv1afn.com/j310preamp.html)

4. RF transistors (BFS17P)

5. PA redesign (normal push pull design, two stage of IRF530 ) use BFQ19S for drivers

6. More filters on the output

7. Maybe change of the mixers to JFET mixers

 

I started to put together my own design, so I have some sketches. I can share if you interested.


--

…_. _._

Re: Personal Best Distance, SSB Phone #ubitx

 

Allison,

 

Well my eyesight is not as good as it used to be. However, the ND6T schematic did not identify K1 and K2 as relays so I was not sure where to look. Plus, the “K” for K1 on my board was obliterated by being screened over a hole so all I can read is “1”. Regardless, thanks for pointing me in the right direction.

 

David A Posthuma, WD8PUO

1 (616) 283-7703

 

From: BITX20@groups.io <BITX20@groups.io> On Behalf Of ajparent1/KB1GMX
Sent: Wednesday, September 05, 2018 2:35 PM
To: BITX20@groups.io
Subject: Re: [BITX20] Personal Best Distance, SSB Phone #ubitx

 

David,

I pulled a copy of the V4 schematic and guess what.  They are marked, and at the bottom
of the page and K1 is extreme left and k3 is extreme right.  So no need to guess.

K3 is next to the antenna connector and it says so right next to it. The writing is
between the relay and the antenna pin plug.

K1 is on the opposing side next to the power connector and it is also labeled!

I wear glasses to read (+1.6) and if I can see that without them then one hasn't looked closely.

Allison

Re: Personal Best Distance, SSB Phone #ubitx

 

Sorry, I was trying to connect with Don specifically as I was instructed by Kees, but I didn’t have his email. His name led the post so I hoped he would see it and respond.

 

David A Posthuma, WD8PUO

1 (616) 283-7703

 

From: BITX20@groups.io <BITX20@groups.io> On Behalf Of ajparent1/KB1GMX
Sent: Wednesday, September 05, 2018 2:37 PM
To: BITX20@groups.io
Subject: Re: [BITX20] Personal Best Distance, SSB Phone #ubitx

 

David, by the way the topic is  "Personal Best Distance, SSB Phone #ubitx"

Why did you post about not finding things about the schematic here???????

Allison

Re: Stone Soup

Bill Cromwell
 

Hi Richard,

It's not a good idea to violate FCC regulations if you are licensed and/or operate in the U.S.A. If you annoy somebody you will know by the loud moaning and whining.

73,

Bill KU8H

On 09/05/2018 11:20 AM, RICHARD wrote:
So it’s OK to violate FCC regulations , if you do not annoy anybody? How
do you know?



Sent from Mail <https://go.microsoft.com/fwlink/?LinkId=550986> for
Windows 10



------------------------------------------------------------------------
*From:* BITX20@groups.io <BITX20@groups.io> on behalf of SM6MOJ
<@Aeronaut>
*Sent:* Wednesday, September 5, 2018 3:29:45 AM
*To:* BITX20@groups.io
*Subject:* [BITX20] Stone Soup


At last, my µBITX is configured and I can use it for local contacts on
80 m, together with a Pi-filter antenna matcher and a G5RV antenna. The
band is quiet at 09.00 local time and I am not likely to annoy anybody
with spurious emissions.

The discussions about filters and spurious emissions go right over my
head, since I do not have access to a lot of expensive lab gear. This
can be left to those who have access to equipment and better knowledge
than I have.

I bought a Wehrmacht receiver about 20 years ago. Although it was then
about 50 years old, its calibration was still spot-on. It was quite
simple, electrically, but was ruggedized and field-serviceable. Many of
the components were located in individual diecast aluminium enclosures.
Thinking about the discussion about µBITX filters, I realised that it
would be reasonable to assume that the cross-talk etc. that people
complain about could be cured or reduced by putting each filter unit in
its own metal box.

So I offer the challenge to those who know better than I do - please
install metal shields round each individual filter and tell us what happens.

While you are at it, you could also test rigs like the HW-7 or HW-8 and
tell us about their spurious emissions.

--
bark less - wag more

Re: Stone Soup

Arv Evans
 

Allison

Somehow your earlier information got lost in others old timer stories about 11 meters
and such.  Now that Raj has suggested a good fix along these same lines maybe we
can continue the focus on that as a solution to the spurs issue. 

Progress is wonderful when it actually happens.   8-)

Arv
_._


On Wed, Sep 5, 2018 at 8:03 AM ajparent1/KB1GMX <kb1gmx@...> wrote:
The idea of tunable traps is impractical. 
Another example of its simple, it will fix everything. NOT!

Unless you have a inline spec ana how do you know its properly tuned and 
adeqauate suppression????
At best its a poorly applied bandaid, at worst a bad hack.

What does work is a band pass filter as it passes what we know we want.
Another approach is suppress the trash getting into the IF and contributing 
signals we do not want.  See the posting Raj has made it goes more aggressively
down a path I tried and has a significant impact.

Allison

si5351 crosstalk #radiuno

ajparent1/kb1gmx
 

Another stone turned.

While testing VFO/BFO replacement for an Atlas210 I came across a spur at the BFO frequency 
while looking at the VFO signal quality.  I first figured it was layout or some error.  Sadly it was not.
As the Atlas210 was a high performance radio for ts day this would compromise it.  For that the
crystal oscillator BFO goes back in.

So I went to the Raduino and did some research and built two other commercial SI5351 breakout
boards to test for CROSSTALK.   Indeed if you load (resistive load) a oscillator port you will see
it as a weak spur on the other operating port.  The amount of the spur is proportional to the
load current for that oscillator.  Its chip level not board level.

Two oscillators 0 and 2 operating with 0 set for 4.0000mhz and 2 set for 5.520mhz.

The output hooked to SA via 3db pad.  Its output is measured as 8.94 DBM, I expected 13!
Not a big problem and clean.  Add a 50 ohm laod to osc-2 and there it is at 5.520mhz, a
signal exactly 58dbc.  Move SA to osc-2 and big as life and 8.94 DBM again (where is the 13dbm?)
and sure enough a -58dbc spur at 4.0000mhz.  Take the load off the 4mhz osc-0 and
the spur drops into the noise about -90dbc down.

Seems running multiple oscillator lowers the output power of any one too.

Make the load resistor 25ohms and it gets about 6db worse and at 240ohms its about -70dbc.

These do not effectively cause spurs of consequence for TX output. 

However this does help explain why an external crystal osc was needed to get
carrier leakage to a expected level.  Also where the receiver birdies are coming
from.  Its not the Raduino its the 5351 chip.   This makes it a poor LO replacement
unless its the sole operating oscillator as even the lowly AD9850 DDS 
has about the same SFDR (spurious free dynamic range).  IF only one oscillator is
in use the signal has no spurs only harmonics.

In short for higher performance radios only use one oscillator in the 5351 and
use multiple 5351s is you need more oscillators.

Allison

Re: si5351 crosstalk #radiuno

Gordon Gibby <ggibby@...>
 

What a cool discovery!


On Sep 5, 2018, at 15:31, ajparent1/KB1GMX <kb1gmx@...> wrote:

Another stone turned.

While testing VFO/BFO replacement for an Atlas210 I came across a spur at the BFO frequency 
while looking at the VFO signal quality.  I first figured it was layout or some error.  Sadly it was not.
As the Atlas210 was a high performance radio for ts day this would compromise it.  For that the
crystal oscillator BFO goes back in.

So I went to the Raduino and did some research and built two other commercial SI5351 breakout
boards to test for CROSSTALK.   Indeed if you load (resistive load) a oscillator port you will see
it as a weak spur on the other operating port.  The amount of the spur is proportional to the
load current for that oscillator.  Its chip level not board level.

Two oscillators 0 and 2 operating with 0 set for 4.0000mhz and 2 set for 5.520mhz.

The output hooked to SA via 3db pad.  Its output is measured as 8.94 DBM, I expected 13!
Not a big problem and clean.  Add a 50 ohm laod to osc-2 and there it is at 5.520mhz, a
signal exactly 58dbc.  Move SA to osc-2 and big as life and 8.94 DBM again (where is the 13dbm?)
and sure enough a -58dbc spur at 4.0000mhz.  Take the load off the 4mhz osc-0 and
the spur drops into the noise about -90dbc down.

Seems running multiple oscillator lowers the output power of any one too.

Make the load resistor 25ohms and it gets about 6db worse and at 240ohms its about -70dbc.

These do not effectively cause spurs of consequence for TX output. 

However this does help explain why an external crystal osc was needed to get
carrier leakage to a expected level.  Also where the receiver birdies are coming
from.  Its not the Raduino its the 5351 chip.   This makes it a poor LO replacement
unless its the sole operating oscillator as even the lowly AD9850 DDS 
has about the same SFDR (spurious free dynamic range).  IF only one oscillator is
in use the signal has no spurs only harmonics.

In short for higher performance radios only use one oscillator in the 5351 and
use multiple 5351s is you need more oscillators.

Allison