Date   
Re: Blown Finals AGAIN!

R.Putnam
 

Hi Alan,
Thanks for your response. You have made me dig deeper! I have downloaded The Fault finding pages for transmit signal path and also the transmit block diagram.
73
Richard G0ILN.

Re: New kit: 50W PA for QCX

Art N4EZZ
 

There is a selection of english dictionaries for libreoffice.

Somewhere along the way it turns out that I have installed all of them.

https://extensions.libreoffice.org/extensions/english-dictionaries

Art N4EZZ <n4ezz@...>
GnuPG key ID 0x6712DD0E
=============================
Greed and hate have caused most of the misfortune in the world
throughout history, so we should all examine our motives continually.
Me

On 12/13/19 1:36 PM, Richard G4TGJ wrote:
My LibreOffice (6.3.3.2) has English (UK). This is on Windows 10 - are you on Linux? I don't know if that makes a difference.
--
73
Richard
G4TGJ



Re: New kit: 50W PA for QCX

Richard G4TGJ
 

My LibreOffice (6.3.3.2) has English (UK). This is on Windows 10 - are you on Linux? I don't know if that makes a difference.
--
73
Richard
G4TGJ

Re: New kit: 50W PA for QCX

harleyleenuke
 

Seems like someone added a Hillbilly Spell Checker to the pdf software.  

No worries,  I can understood that whut ya right.

Re: New kit: 50W PA for QCX

Hans Summers
 

Hi Richard

I found the problem with my spellchecker... my document was configured as "English (UK)" but LibreOffice only has an "English (US)" dictionary available. The spell check gave NO complaints... I should have been suspicious about that of course, but missed it in my excitement. So now I have taken the easy solution and configured the language as "English (USA)" then ran the spellcheck and fixed lots of complaints; and ignored when it complained about "colour" hi hi. 

So all fixed now... latest document is uploaded. 

73 Hans G0UPL

On Fri, Dec 13, 2019 at 10:53 PM Hans Summers via Groups.Io <hans.summers=gmail.com@groups.io> wrote:
Thanks Richard

I will correct those errors.

Spellcheck... I did run a spellcheck! Why didn't it find any of it. Arrghhh... will try again...

73 Hans G0UPL 

On Fri, Dec 13, 2019, 22:50 Richard G4TGJ <rpt@...> wrote:
Hi Hans
Another masterpiece and I really enjoyed the circuit explanation especially about the PIN diode switching.But (version 1.00e):
  1. On page 64 section 7.3 you suggest powering the QCX from a 7805. I think you mean 7812 - it says this in section 7.2.
  2. On page 48 "it does occur at 5V for lower voltage settings" should say 5A.
  3. There are very many typos throughout. A spell check would spot these.
--
73
Richard
G4TGJ

Re: New kit: 50W PA for QCX

Hans Summers
 

Thanks Richard

I will correct those errors.

Spellcheck... I did run a spellcheck! Why didn't it find any of it. Arrghhh... will try again...

73 Hans G0UPL 

On Fri, Dec 13, 2019, 22:50 Richard G4TGJ <rpt@...> wrote:
Hi Hans
Another masterpiece and I really enjoyed the circuit explanation especially about the PIN diode switching.But (version 1.00e):
  1. On page 64 section 7.3 you suggest powering the QCX from a 7805. I think you mean 7812 - it says this in section 7.2.
  2. On page 48 "it does occur at 5V for lower voltage settings" should say 5A.
  3. There are very many typos throughout. A spell check would spot these.
--
73
Richard
G4TGJ

Re: New kit: 50W PA for QCX

Richard G4TGJ
 

Hi Hans
Another masterpiece and I really enjoyed the circuit explanation especially about the PIN diode switching.But (version 1.00e):
  1. On page 64 section 7.3 you suggest powering the QCX from a 7805. I think you mean 7812 - it says this in section 7.2.
  2. On page 48 "it does occur at 5V for lower voltage settings" should say 5A.
  3. There are very many typos throughout. A spell check would spot these.
--
73
Richard
G4TGJ

Re: Low pass filters

Richard G4TGJ
 

Hi Luc
Yes, I had assumed I could but hadn't yet looked into it. I like your arrangement and will do something similar. Thanks.
--
73
Richard
G4TGJ

Re: New kit: 50W PA for QCX

Michael St.James
 

Hans,
You are one of a kind and much appreciated. 👍

MikeinMinnesota N0WDM

Re: Quadrature modulation: The signal behind digital communications | EDN

ajparent1/KB1GMX
 

Based on 50 years of doing the engineering thing 11th year math (applied algebra, trig,
and calculus) covered most of the cases in the slide rule era  for all but the most
exotic, computers solved the rest.  

On average a solid understanding of arithmetic helps.  Why?  The most common
problems rely on add subtract, multiply and divide and take a occasional square
root or log.  The latter two were made easier to do with a slide rule and later
pocket calc. The most often use application on my iPhone is the calculator!

For the missing part it is how is that applied and what does it mean.
RFD and EMRFD and SSD are classics that can answer better than 97%
of engineering level questions, the rest you need the antenna design books.
the Radio Amateurs Handbooks over the years were remarkable in the breadth
of subject matter.  As a kid in the 60s they supplied the answers or a good
idea where and what to look for in the library (long before before Altavista
and later google).

Allison
--
Please reply on list so we can share.
Off list email goes to trash, I had to due to scrapers.

Re: Quadrature modulation: The signal behind digital communications | EDN

jjpurdum
 

Takes me back to when I was getting ready to go into the 9th grade. My home town was a small farming community and after the 8th grade, you and your parents went in to meet with the counselor to decide whether you were going to go into a pre-college or vocational track. The counselor asked what I wanted to do (I had my General class license). I told him I wanted to be an Electrical Engineer. He looked at me, then told my parents I wasn't smart enough to go to college and that I should plan on fixing farm equipment.

I can't even begin to relate the impact that had on me. On the plus side, my parents and I ran into him about 10 years later after I got my Ph.D. and he asked if I went to college. I said "Yes" and he asked what I was doing. I said I was teaching at Creighton University. His eyes went as big as pie plates, and he said rather sternly: "You know you'll have to get your Ph.D. to keep teaching." I said: "Yep, already got that." He said: "No shit!" and then apologized to my parents for the foul language. It was a good day.

Jack, W8TEE

On Friday, December 13, 2019, 1:22:49 PM EST, Eric KE6US <eric.csuf@...> wrote:


There was a recent question in, I think, QRP-Tech group (now on groups.io) asking what level of math is required to understand W7ZOI's Radio Frequency Design.

This article shows that much of it was covered in high school math (OK, what would be called AP Math today). That doesn't in any way detract from the level of math used by practicing engineers in some cases, but it shows that the level needed to understand and successfully homebrew some very interesting designs is well within the reach of most hams.

Thanks for posting the article.

Eric KE6US

On 12/13/2019 9:17 AM, SkipF, NT1G wrote:

Re: Low pass filters

ajparent1/KB1GMX
 

I'm with Hans on this.

Experience is two T37-2 toroids wound with 20 turns had a  15% variation
in measured inductance at 7mhz using a calibrated P4191A.   One tight 
and closely spaced to maybe 65-70% of the space the other loose and 
covering near 95%.  When stripped and measured the loose one also
had a significant amount more wire, inductance free space or on a
former is dependent on the amount of wire used.  As to pulling hard
enough to break #28 you are likely pulling way to hard.  ;-)

Since iron powder is not spec'ed as exact or even 5% seeing variations 
is nominal case.  Most have a Temp coefficient  +35-50ppm!/degree-C.

What does that mean, if shown a picture of how the sample was wound
one might want to consider that a strong suggestion.  The other is if told
there may be tuning likely because its not a wide band design and can't
be with class-E amp.  Do the tuning.

The tolerances of ferrite (actually its iron powder Txx-xx part not FTxx-xx) ,
caps, and winding style can easily fall out of range.  The first two are verifiable
the third tends to map widely.

Add to that the unknowns like small difference in lead lengths and distributed
capacitance all tend to gang up.  Further L4 and C30 are critical  values
for class E performance and they do interact with the low pass filter.

As to Tonne software and experience while I have always seen errors
when I went back and measured and then plugged in the real values it
was always correct.  One of the items you can plug into models is the
real effect of circuit traces!

What are the real values... inductance of the coils at the operating frequency
(It does change with frequency due to distributed capacitance and mu of the iron
powder inductors).  The actual value of the capacitors, and additional capacitance
of the board or wiring.  If all are 5% (in electronics that is pretty good!) consider
the effect on Fc of a low pass filter, that can push the Fc around by 350khz easily
at 7mhz!

Allison
--
Please reply on list so we can share.
Off list email goes to trash, I had to due to scrapers.

Re: Quadrature modulation: The signal behind digital communications | EDN

Bill Cromwell
 

Hi Eric,

I don't have that book yet but I can get by if I take my shoes off so I can count on my toes as well as my fingers. The 'old' math.

73,

Bill KU8H

On 12/13/19 1:22 PM, Eric KE6US wrote:
There was a recent question in, I think, QRP-Tech group (now on groups.io) asking what level of math is required to understand W7ZOI's Radio Frequency Design.
This article shows that much of it was covered in high school math (OK, what would be called AP Math today). That doesn't in any way detract from the level of math used by practicing engineers in some cases, but it shows that the level needed to understand and successfully homebrew some very interesting designs is well within the reach of most hams.
Thanks for posting the article.
Eric KE6US
On 12/13/2019 9:17 AM, SkipF, NT1G wrote:
https://www.edn.com/electronics-blogs/fun-with-fundamentals/4462467/Quadrature-modulation--The-signal-behind-digital-communications
--
bark less - wag more

Re: Low pass filters

ON7DQ Luc
 

Richard,

You do know you can measure Inductance with your nanoVNA very well ?

I made a small "component-adapter", and use it very frequently (see picture).
It's a 4 pin header, two pins to ground, two pins to center of the SMA connector.
I also made a simple 4 pin CAL set,first two pins shorted, center pins open, and a 49,9 Ohm resistor between the last two pins.
(50 Ohm CAL shown in the picture)
The two center "hooks" are bent up slightly to measure SMD components.
Put the nanoVNA in single frequency mode on a low frequency (I use 50 kHz, but using your "working frequency", e.g. 7 MHz,  works too).
73,
Luc - ON7DQ

Re: Quadrature modulation: The signal behind digital communications | EDN

Eric KE6US
 

There was a recent question in, I think, QRP-Tech group (now on groups.io) asking what level of math is required to understand W7ZOI's Radio Frequency Design.

This article shows that much of it was covered in high school math (OK, what would be called AP Math today). That doesn't in any way detract from the level of math used by practicing engineers in some cases, but it shows that the level needed to understand and successfully homebrew some very interesting designs is well within the reach of most hams.

Thanks for posting the article.

Eric KE6US

Re: 100+ Amp kits...

Michael N6MST
 

I hope one is in the queue for me! Sister-in-law was asking for ideas on what to get me for Christmas yesterday. I simply sent her the link to the amp page and didn't hear anything back from her :)

Re: Low pass filters

Richard G4TGJ
 

Hi Hans
Thanks for the thorough reply. I tried squeezing the turns but could not get the response to match the expected. I think your point about loose turns is a good one although I did try to make the windings as tight as I could.

So it does sound like their is a toroid issue. Not with the toroids themselves but with the calculations.

I will have to get myself an LCR meter for Christmas.
--
73
Richard
G4TGJ

Quadrature modulation: The signal behind digital communications | EDN

SkipF, NT1G <skip.flem@...>
 

Re: Low pass filters

Hans Summers
 

Hi Richard

There is a lot of variation, but I believe more of it is in winding styles than in the toroid characteristics.

The theoretical values for the number of turns are often quoted. But these are calculated assuming somewhat perfect conditions, including equally distributed winding around the circumference of the toroid. Practically we are often told to leave a from start to end, which some say is for the purposes of minimizing capacitative coupling; the recommended gap is sometimes 30-degrees or 10% (36-degrees) for example. Squeezing turns together increases the inductance; leaving a gap is like squeezing turns together. 

Another thing that increases inductance is looser windings. It's very difficult to wind so tightly that the wire touches the toroid surface all the way round. With fine wire such as the AWG #28 (0.3mm) used in QCX, if you try to pull it too tight, it snaps. With thicker wire, it doesn't bend so easily so it's even harder to get it wound tightly. This also increases the inductance. 

I feel that all this variation in winding style is more to blame for inductance variation than the material tolerances themselves. 

I can't remember having seen a real world measured inductance that is LOWER than the predicted inductance from the calculation. The calculated number of turns always seems to result in too high an inductance value. It makes no difference whether the cores are original micrometals or not. 

I think these differences are all down to the gap between theoretical models and real world situations. 

73 Hans G0UPL 


On Fri, Dec 13, 2019, 13:08 Richard G4TGJ <rpt@...> wrote:
A number of people have had problems with the power output of their QCX and the solution has often been to remove a turn or two from L1-L3. I have been working on my own transceiver and I have been using the W3NQN CWAZ LPF designs from the GQRP Club datasheet. I've been analysing the 20m LPF with my nanoVNA and have had to remove 2 turns from L2 and L6 and 1 turn from L4 to get a satisfactory passband return loss and insertion loss. That's a change in inductance way beyond the 5% tolerance of AL or the 5% capacitance tolerance. Has anybody else done similar tests? Is there a widespread problem with the toroids? Mine came from GQRP Club Sales so I assume they are Micrometals.
--
73
Richard
G4TGJ

Re: Low pass filters

Arv Evans
 

It is difficult for on-line resonnance calculator programs to know how much distributed capacitance and distributed inductance is present in the actual circuit.  This sometimes causes the calculated values to be incorrect.  

Arv. K7HKL
_-_


On Fri, Dec 13, 2019, 4:00 AM Richard G4TGJ <rpt@...> wrote:
Sorry, have you woken up after a bad night?

I've used Tonne Software's Elsie to analyse the W3NQN design and it should work well but my measurements do not match it. So I've hardly instantly come to any conclustions. It was a question for the community to give their considered and informed response.

The problem isn't solved because it means designs may not be repeatable.
--
73
Richard
G4TGJ