Date   
Re: SWR Meter Recommendations for QCX

Chris Herd
 

Hi

Try this one

https://www.tindie.com/stores/NM0S_qrp/

It is his store. 

Best regards 

Chris

Re: Measuring output watts with an oscilloscope

Tim
 

I snorted my coffee when I read this....


If I hadn't there would no doubt be a pack of tightly-coiled pedants ready to spring into action. For everyday use there's absolutely no need for anything like that level of accuracy.
Brilliant!

cheers

Tim

--
VK2XAX : QF56if : ITU59 : CQ30 : BMARC : WIA

Re: Measuring output watts with an oscilloscope

Eric KE6US
 

It still is 99.08723% of the time.

Eric KE6US

On 1/23/2020 9:24 AM, geoff M0ORE via Groups.Io wrote:

Some amateurs, especially those new to the hobby, don't appreciate the difference between accuracy and resolution.

Just because an instrument gives a resolution to several decimal places does not mean that it is accurate to that degree. When we all used moving coil multimeters, to get within a few per cent was plenty good enough.


On 23/01/2020 12:44, Ronan Cantwell wrote:
On Wed, Jan 22, 2020 at 09:23 AM, Alan G4ZFQ wrote:
= 5.0625 Watts
Close enough for government work.....
Ronan,

I wish people would recognise that such precision is not needed.
I'd think +/-5% for a scope reading even disregarding waveform linearity
would make that about 5 Watts. If you really want decimal points around
4.8 to 5.3 Watts?
And who really knows how accurate their readings are?

73 Alan G4ZFQ
Agreed 100% (+/- 10%) Alan...... That's kind of why I put all the loose change in the result - to make a point. If I hadn't there would no doubt be a pack of tightly-coiled pedants ready to spring into action. For everyday use there's absolutely no need for anything like that level of accuracy.

Cheers,
Ronan MM0IVR

Re: Measuring output watts with an oscilloscope

geoff M0ORE
 

Some amateurs, especially those new to the hobby, don't appreciate the difference between accuracy and resolution.

Just because an instrument gives a resolution to several decimal places does not mean that it is accurate to that degree. When we all used moving coil multimeters, to get within a few per cent was plenty good enough.


On 23/01/2020 12:44, Ronan Cantwell wrote:
On Wed, Jan 22, 2020 at 09:23 AM, Alan G4ZFQ wrote:
= 5.0625 Watts
Close enough for government work.....
Ronan,

I wish people would recognise that such precision is not needed.
I'd think +/-5% for a scope reading even disregarding waveform linearity
would make that about 5 Watts. If you really want decimal points around
4.8 to 5.3 Watts?
And who really knows how accurate their readings are?

73 Alan G4ZFQ
Agreed 100% (+/- 10%) Alan...... That's kind of why I put all the loose change in the result - to make a point. If I hadn't there would no doubt be a pack of tightly-coiled pedants ready to spring into action. For everyday use there's absolutely no need for anything like that level of accuracy.

Cheers,
Ronan MM0IVR

Re: SWR Meter Recommendations for QCX

Al Clark
 

The order link on the NM0S website works for me.  When I click on it I get a good Ebay page.  Perhaps it was down temporarily.
--
Al W4KY

Re: SWR Meter Recommendations for QCX

Bernard A. Poskus
 

I emailed him to ask about it after having the same experience.  Here is his reply:
Just search for QRPOMETER on eBay.
73 de Bernie, KF0QS

Re: !/2 Voltages On QCX 20

ajparent1/KB1GMX
 

Great!  That's the desired result.

-------------------------------
Please reply on list so we can share.
No direct email, it goes to bit bucket due address harvesting in groups.IO

Re: Measuring output watts with an oscilloscope

ajparent1/KB1GMX
 

At one point in time I was doing a fair amount of metrology as I was a resident engineer.
Someone show me U for V and justifiably laughter broke out.  Seriously, whats wrong
with V as in electronics V, A, W are SI units.  Unless you ant to work in columbs, joules,
and Newtons/seconds.  ;-)

Me I did a lot of antenna design (employed!) and Si units there were not common
save for I could it much easier to work in meters.  It was painful as old papers
from teh teens 20 and 30s (1910) were often in feet.   ;)

Allison
-------------------------------
Please reply on list so we can share.
No direct email, it goes to bit bucket due address harvesting in groups.IO

Re: Measuring output watts with an oscilloscope

Evan Hand
 

Thank-you for the response.  When I looked up SI voltage symbol I got v, reason for my question.  I did not want to use it if not appropriate.

Again Thank-you.
73
Evan
AC9TU

Re: QCX CAT Questions .... #cat #qcx

jmh6@...
 

Hi Rick,

I soldered two 330 resistors to the LCD pins. I also brought out gnd.

I used 3 clipped leads to connect from there to an Arduino with its DIP 324 chip unplugged. Works great.

I run Linux and used minicom to talk to the Arduino and then on to my QCX20.

Lots of fun :).

On Wed, 22 Jan 2020, Rick Williams - VE7TK via Groups.Io wrote:

I'm about to do the CAT and PTT mods to my QCX20 and have a couple of questions concerning the CAT mod.
Is the best place to pick off the DVM, LCD_4 and LCD_5 directly off of IC2 - pins 25, 2 and 3 respectively? Or would the LCD pins 4 and 5 and the junction of R56, R57 and
R58 (for the DVM) be more appropriate?
With respect to the USB to Serial Converter I have a USB TTL Serial Cable PL2303TA. It "claims" to have a real PL2303TA chip and works with WIN10. The actual title of the
cable is USB TTL RS232 Convert Serial Cable BUT the pin-out is all at 5 VDC level suggesting TTL.
For an external connection my plan is to take the TX, RX and GND from the QCX to a 3.5 mm stereo jack on the case and then, via 3.5 mm plug, to the converter.
If others who have completed the mod have any hardware suggestions please advise!
Thanks.
--
73, Rick
VE7TK

Re: SWR Meter Recommendations for QCX

Gregg Myers
 

On Thu, Jan 23, 2020 at 7:21 AM <KC1KNC@...> wrote:
Trying to place an order from the NM0S web site leads to an Ebay page that no longer exists:
https://www.ebay.com/itm/QRPoMeter-Digital-15W-QRP-Wattmeter-Dummy-Load-VSWR-Meter-Kit/254303433148?hash=item3b35aa71bc:g:fgAAAOSwlY1ZMMdT

Re: SWR Meter Recommendations for QCX

KC1KNC@...
 

Trying to place an order from the NM0S web site leads to an Ebay page that no longer exists:
https://www.ebay.com/itm/QRPoMeter-Digital-15W-QRP-Wattmeter-Dummy-Load-VSWR-Meter-Kit/254303433148?hash=item3b35aa71bc:g:fgAAAOSwlY1ZMMdT

Re: Measuring output watts with an oscilloscope

Roy Appleton
 

That's a great chart but there's nothing small about it. I was going to print it and it was going to be 9 pages!

Roy
WA0YMH

On Wed, Jan 22, 2020, 8:42 AM James Daldry W4JED <jim@...> wrote:

Hi, Folks

The University of Hamburg Germany has a nice little chart to print out and stick on the wall of your shack. It starts at the top at -180 dbm and ends at the bottom at +60 dbm in 50 ohms. It lists dbm, watts, volts rms, volts peak, and volts peak-to-peak in 1 dbm increments. The url is:

http://wera.cen.uni-hamburg.de/DBM.shtml

Cover it with a sheet of plastic so you can wash off rosin-y fingerprints.

73

Jim W4JED

On 1/22/20 2:23 AM, mike.carden wrote:
Do I square it or halve it? Is it 1.414 or 0,707 or root two over Pi over e to the power of your grandmother's birthday?

I'm only half joking. A forum thread is a *terrible* place to look for established simple calculations. It's the place where typos, inattention, miscommunication and ignorance conspire to get almost, but not quite, everything wrong.

-- 
MC
VK1MC


Re: Measuring output watts with an oscilloscope

George Korper
 

Thank you Hans. That is a mice addition to the website and my documentation. 
😁
Squeezing out the last watt has been one of my problems, and really it is STUPID.
From now on I will take my hands and give myself a slight jolt on the noggin when I look at 
a wattmeter. Old age doesn't always amount to maturity. The paper you wrote actually
applies some lacking discipline. 

On Wed, Jan 22, 2020 at 7:12 AM Hans Summers <hans.summers@...> wrote:
Hi all

Thanks to the many good folks who have contributed to this thread. 

This topic crops up from time to time. Along with people who use the QCX RF Power function and see much higher power at middle points of the LPF; or 5.2W at the drains of the BS170s... all of which are incorrect. A lot of confusion exists and is multiplied when well-intentioned people add typos in their posts or ambiguities through haste or inattention. 

To resolve the matter once and for all, and draw attention to all the issues involved, which can result in inaccuracy, I hereby present my new article:
"The definitive guide to RF Power measurement"
at:

In future, whenever this question crops up, all we need to do is point people at this page, rather than regurgitate the same confusions all over again. 

73 Hans G0UPL


Re: !/2 Voltages On QCX 20

George Korper
 

Allison, thank you very much. There was a problem with a connection under T1 which goes back to the solder I was 
using on my first QCX build. I purchased the Kester solder you recommended and have not had these problems since.
So thank you on two accounts!

Re: Measuring output watts with an oscilloscope

Ronan Cantwell
 

On Wed, Jan 22, 2020 at 09:23 AM, Alan G4ZFQ wrote:
= 5.0625 Watts
Close enough for government work.....
Ronan,

I wish people would recognise that such precision is not needed.
I'd think +/-5% for a scope reading even disregarding waveform linearity
would make that about 5 Watts. If you really want decimal points around
4.8 to 5.3 Watts?
And who really knows how accurate their readings are?

73 Alan G4ZFQ
Agreed 100% (+/- 10%) Alan...... That's kind of why I put all the loose change in the result - to make a point. If I hadn't there would no doubt be a pack of tightly-coiled pedants ready to spring into action. For everyday use there's absolutely no need for anything like that level of accuracy.

Cheers,
Ronan MM0IVR

Re: Measuring output watts with an oscilloscope

Alan G4ZFQ
 

Do you have a reference to the SI use of U for voltage?  When I search for it, I get v or V and not U.
Evan,

I'm not sure it is a SI unit

"NEW SI UNIT ADDED
a non-SI unit called “unit,” symbol U, equal to plmol/min, which is not coherent with the SI, has ..."

73 Alan G4ZFQ

Re: QCX CAT Questions .... #cat #qcx

G4GIR
 

Hi Rick
 
I've carried out the mod on all my QCX's and all works well.
 
I tapped onto the rear of IC2 for all the connections.
Fitted a 15 way D connector to the rear panel of the case, this accommodates the GPS connections, the Firmware up grade connections and the CAT connections.
 
The CAT resistors and diode are directly soldered into the buckets of the D connector pins.
As for the TTL Serial connector I made a mistake by ordering a 3.5v level cable, it seemed to work but was quite erratic at times, the 5v cable cured the problems.
The cable is an RS Stock No 6877770 Manufacturers Part No TTL-223R-5V, Guess you could compare what you have with this one.
 
Hope this is of use.
 
CU in the QSO Parties some time.
 
72/3
 
Ian G4GIR
 

----- Original Message -----
From: Rick Williams - VE7TK via Groups.Io <ve7tk@...>
Reply-To: <QRPLabs@groups.io>
To: <QRPLabs@groups.io>
Sent: 23/01/2020 00:24:29
Subject: [QRPLabs] QCX CAT Questions .... #cat #qcx

I'm about to do the CAT and PTT mods to my QCX20 and have a couple of questions concerning the CAT mod.

Is the best place to pick off the DVM, LCD_4 and LCD_5 directly off of IC2 - pins 25, 2 and 3 respectively? Or would the LCD pins 4 and 5 and the junction of R56, R57 and R58 (for the DVM) be more appropriate?

With respect to the USB to Serial Converter I have a USB TTL Serial Cable PL2303TA. It "claims" to have a real PL2303TA chip and works with WIN10. The actual title of the cable is USB TTL RS232 Convert Serial Cable BUT the pin-out is all at 5 VDC level suggesting TTL.

For an external connection my plan is to take the TX, RX and GND from the QCX to a 3.5 mm stereo jack on the case and then, via 3.5 mm plug, to the converter.

If others who have completed the mod have any hardware suggestions please advise!

Thanks.
--
73, Rick
VE7TK

Re: Measuring output watts with an oscilloscope

Evan Hand
 

Marcus,

Do you have a reference to the SI use of U for voltage?  When I search for it, I get v or V and not U.

Trying to be sure that I understand.

Thank-you
73
Evan
AC9TU

Re: Measuring output watts with an oscilloscope

Charles Wells
 

I recall U from the few, mandatory EE classes I had to take in the late 80's.  It seems to have never caught on over here aside from some PhDs I know.

Also, don't most of the basic electrical term transcend the SI/USCS squabble?  Volts, amperes, watts (electrical) are mainly in the universal system, n'est pa?


On Thu, Jan 23, 2020 at 5:06 AM Alan G4ZFQ <alan4alan@...> wrote:
>     U stands for V (Voltage)

  Markus,

Maybe, but most have forgotten or never learnt SI-Units. I do remember
some dispute about it when it was introduced but "U" never seems to have
made it to electronics.

73 Alan G4ZFQ