Saturday, 14 May 2016

U3S Beacon Kit (2) - I search for more RF Power

I have been running the new G0UPL U3S Beacon Kit I built last year for some months now, and I'm very pleased with it's performance.  On 30 metres, I have been seen by W4HBK in Florida, EA8BVP in the Canary Islands, KL7L in Alaska, and SA6BSS in Sweden.

I have been running a pair of BS170's on 5V, and on 30M they produce 270mW of RF to the antenna.

I had read an article by Hans Summers G0UPL, the kit's designer, regarding the efficiency of the U3S PA, and a method he had tried to increase the RF Power from the unit without modifying it too much.  This consisted of changing the configuration of L1 the inductor  feeding the Drains of the PA MOSFET's.  See Hans' original article HERE.  I could easily reproduce his "safe Power" limits on 40M and 30M, but further reading elsewhere convinced me I could get more from these limits by increasing the efficiency of the PA.  A couple of sources I used were HERE and HERE.

I used a single Amidon BN43-202 2 hole Balun Core with 2T of miniature 50 ohm coax wound in it.  The inner of one end was joined to the outer of the other end and became the centre tap. The free outer was connected to the 5V rail and the free inner at the other end to the output coupling Capacitor C5.  The Centre Tap was connected to the 2 BS170's Drains.  The core lies on it's side, there is plenty of space for it on the board, without touching the board above, the OCXO.  I anchored it in place with a piece of double-sided sticky tape.
Drawing of new L1

With 5V on the BS170 drains (See how to set drain current by Hans' Summers "Safe Quiescent Current"), however I set the Quiescent Current to just 0.0 mA I get:

40 Metres                 420 mW
30 Metres                 390 mW

I replaced the spare toggle Switch with a single pole 3 position switch, and added a 7809 9V regulator, as per my earlier Blog.  I can now switch the PA to "Low power" - "Off" - "High power".

With 9V on the BS170 drains (Quiescent Drain Current set as above) I get:

40 Metres                1100 mW
30 Metres                1050 mW

In either case the 2 BS170's are running well within their limits, only getting warm to the touch.  No finger tips or BS170's were harmed in this experiment.

Pete Mulhare
14 May 2016

Sunday, 17 January 2016

Using ON7YD's "QRS" PC Software to key QRSS Beacons.

ON7YD’s QRS Software is available HERE .  It enables an Operator to use a PC running up to Windows10 to key a QRSS Beacon with little further hardware required.  These instructions are to get the Beacon keying in a 10 minute Sequence that is “Stackable” for a Grabber Operator, further enhancing your chances of being seen on air.  I refer here to V4.14 of QRS.

See my Web Site HERE to find out more about "Stacking" Grabber Frames. 

To get the Callsign transmitting every 10 minutes starting at DELAY after the hour:  Note: DELAY can = 0.

Port         = Your choice.
Speed      = 6 seconds. (QRSS6) - ie 6 second Dots.
Text 1      = Your Call - QRS gives the time it takes to send your Call time at “Speed
Repeat    = 0 minutes, Interval = 10 minutes.  (0 minutes = repeat for ever)
Mode       = QRSS, dash-dot ratio = 3.
Alarm      = 0 seconds.
Sound     = CW & QRSS - disable when in use!  Use as a monitor.
DFCW     = Ignore settings unless using DFCW.
CW ID      = Start disabled, Stop disabled.
Sync        = Disabled.

Later = Start Time (HHMMSS). 
The next time interval; from now.  Enter the time as DELAY time past the hour, or a 10 minute interval after the hour (plus DELAY).  For example: 090030, 091030, or etc.  This gives a (say) 30 second DELAY before the (say) 6 minutes 30 seconds for your callsign and another 3 minute 00 seconds at the end of the callsign send time.  Your Callsign is 6 minutes 30 seconds long at QRSS6 (6 second dots) which is quite adequate for most bands. The DELAY pushes the Callsign to the right in the displayed Image. (Each callsign will take a different time to send!)

So what happens?  At 00 minutes past the hour, or 10 mins or, etc.....
1          QRS starts and waits for DELAY time (say) 30 secs.
2          Sends your call for the (say) next 6 min and 30 secs.
3          Waits 3 minutes and 00 Seconds (0:30 + 6:30 + 3:00 = 10:00 minutes)
4          Restarts at the next 10 minute interval.
5          Note that on the first frame QRS may misreport the next interval by 
           1:00 minute.  This will be correctly reported for subsequent frames.

Your Computer Clock must be synchronized to UTC, use “Dimension4” (nice easy little program to keep your clock in sync from an internet NTC Time Server!   -  Google is your friend!   This is so that your clock and mine, and any other Grabber Station is sync'd to the same time......Check, that it is in sync with WWV, “At the tone, the time is…….!”

Your call will now be “stackable” with all your other grabs.

18 Jan 2016

Thursday, 14 January 2016

The things I have learned about SpectrumLab (3)

Programming SpectrumLab's spare Buttons:

Clearing the Waterfall:

Ever wanted a button in SpecLab, that would (say), Clear the Waterfall? Or perhaps Resize the screen to your particular Standard Size?  Well you can program some of the spare buttons on the mains screen of Spectrum lab to do just that, and you can specify a short-cut key to press, for the same action you specify in each button.

Click to enlarge

Normally the buttons numbered #6 to #11 are not programmed, so I have used Button #6 to "Clear the Waterfall", I used the words "Clear Screen" to give me room to add "(F10)" to the Button top.  Here's how to do it.

Right Click Button #6; this menu should open, and fill out the text as shown below:

Click OK when done and Button 6 will now Clear the Water Fall.  If you press F10 on the keyboard the water fall will also be cleared.  

Don't forget to do a save to your "Config" file, before you exit SpecLab!  Otherwise you will have to do this all over again....

Setting a Standard Screen Size:

I deduced that a SpectrumLab screen size of 1247 x 699 pixels would give me a Screen Capture size of exactly 1100 x 640 pixels - a convenient size to show on a modern wide screen monitor with space to spare, and also fit into the screen of the older squarer faced monitors, when viewing my Web Site.  So for convenience in setting the Screen Size, and more importantly the Screen Capture size for both the Screen Captures I display on my Web Site Grabber pages, I used Button #7 to set this automatically for me.

Here is how I programmed Button #7.  Firstly it is important to note, that you have to turn OFF the lock window size parameter in SpecLab **View/Windows**Lock Window sizes** otherwise this button will not work!

Right Click Button #7; this menu should open, and fill out the text as shown below:

Click OK when done and Button #7 will now correctly size the on-screen size of SpecLab to 1247 x 699 pixels, if you press F11 on the keyboard the screen size will also be set.  More importantly the online Captures will be exactly 1100 x 640 pixels allowing you to correctly set the picture size within the html coding for your Web Site.

Do turn ON the lock window size parameter in SpecLab *View/Windows**Lock Window sizes* after resizing the screen as this will prevent inadvertent changes in Screen size occurring at embarrassing moments!

Don't forget to do a save to your "Config" file, before you exit SpecLab!  Otherwise you will have to do this all over again....

Pete Mulhare
15 Jan 2016

Saturday, 9 January 2016

The things I have learned about SpectrumLab (2)

Adding a DSP Noise Blanker:

I have been using the Grabber on 40 metres recently, and had a terrible time with QRN crashes from lightning in thunderstorms around the Oceania Region.  The crashes are so bad they obliterate incoming QRSS signals completely at times.

SpecLab has a secret weapon to combat QRN!  I have learned that SpecLab has built in DSP Noise Blankers, which are completely configurable!  After reading the help file on the NB's and learned how to configure them correctly, I was utterly amazed at how effective they are.

How to configure a DSP Noise Blanker and get it up and running:-

You will need to reconfigure the default setting of Speclab in the **Components**Circuit Window** menu.  The default setting for the input to Spectrum Analyser1 is circuit point L1, this needs to be changed to circuit point L2 to include Blackbox1.  To do this click the box with "L1" in it shown wired to Spectrum Analyser1 (lower/centre).  In the pull down menu that appears click "L2=Left Blackbox1" then click OK.  You should have what is shown below on screen.

Spectrum analyser1 is now connected to the output of the left hand Blackbox1, this is where a Noise Blanker resides and can now be enabled.

Click left hand Blackbox1, and a pull down menu appears, select Noise Blanker, and enable it by clicking Noise Blanker and then Mode in the further pull down menu.  Blackbox1 between L1 and L2 should now turn green showing a NB is enabled.

You now need to configure the NB parameters to make it work effectively.

You need a receiver with an antenna connected to it, and setup on the band you want to use.  The noise spectrum from the receiver should fill the lower 5dB or so of the onscreen frequency spectrum.

Go back into the NB pull down and click "Trigger peak/avrg = xx" this will open a further pull down.  Now click "Connect to slider" then "OK".  In the 2 text boxes at lower right on the Components screen - the top one should now say "Noise Blanker Trigger Level L1" and beneath it you will see the level - xxdB.
On the far right of the components Screen there is a vertical slider, now slowly adjust the slider up and down until the yellow frequency Spectrum display just disappears.  Now readjust the slider until the Freq Spectrum reappears just back to it's normal level, now set the lower scale to read +1.0 dB above that normal level.  That is the most important parameter now set.

The rest of the parameters need to be set to the following list:-

Ramp Time = 0.01 sec
Pre-trigger blanking time = 0.0005 sec
Post-trigger blanking time =0.3 sec
Average detector RISE time const = 0.01 sec
Average detector DECAY time const = 0.01 sec

The figures below the dotted line in the NB menu are the current figures for the spectrum you are currently viewing and will change with time.

You can use the slider to adjust the values (don't forget to check the slider box to bring the slider up for that particular parameter) or just enter the figures given into the parameter box directly.  These figures certainly work on 40 Metres for me even with a full blown local thunderstorm raging around me!

The Post Trigger blanking time for me was the trickiest to set.  It needs to be long enough to just completely blank one lightning flash, and 0.3 seconds or slightly shorter seems to be best for me - too little time and you see the end of the noise pulse - too much time, left a black vertical line on the Spectrum screen.  Thicker vertical black lines on the waterfall are where the NB has blanked off multiple strikes, being retriggered several times during the Noise Spike so the shorter this can be, within reason, the better.  You will hardly notice the blanking caused by a single lightning strike - you will hear the spike in the receiver, but it will not show on the waterfall.

The lack of highly coloured vertical lines certainly makes better reading of the waterfall, but the NB will block only short rise time spikes - not QRM from CW, phone or telegraph transmissions.

Don't forget to do a save to your "Config" file, before you exit SpecLab!  Otherwise you will have to do this all over again....

10 Jan 2016

Things I have learned about SpectrumLab

Adding Band, Date/Time to a filename automatically:

I have been using SpectrumLab for my Grabber Software for some years, and I'm still learning new things about it, as I strive to improve what I show on my website.

File naming and saving:

There are a number of ways of saving files automatically in SpectrumLab.  The first is available in the **Options**Screen Capture** tab.

Here you can add in the "Filename" text box, the Drive, route, and filename, for instance "D:\Spectrum\30M\Kapture\Argo.jpg"  This tells SpecLab where to save the file to, and the filename.  SpecLab will then append a "File index", to the filename, so they are not overwritten each time a new file is saved with the same filename.  The File index can be edited by simply over typing the number on the text box.  This all occurs when a **Periodic Action** takes place, which can be programmed to occur at given intervals (10 mins, or 4 hours, say).  See **Options**Periodic Actions** Tab.

I use the extremely simple FTP upload program by ON7YD, ArgoUpload.  Everytime a new file ends up in the directory, this Routine, at the time it uploads the file, strips the filename back to the first 4 characters in the filename.   A File named "Argo1234" will end up being FTP'd to the website as just "Argo" which is exactly what we want!  This action overwrites the older file with the same name already on the website, effectively updating it. 

The above method is fine if you only want a simple file name, because you cannot stop the addition of the file index process.  

I wanted to put in the filename, Band, Date, and Time, for future reference and ease of searching a particular file at a later time.  The appended index number was too simple.  However I was able to come up with another method of doing this, while retaining the name stripping feature of ArgoUpload to handle the overwriting of the file on the website.  This is how I did it.

A feature in SpecLab's Options, will allow the program to carry out specific actions at regular intervals (like every 10 minutes, or 4 hours, say).  See the **Options**Periodic Actions** Tab.  To activate the periodic action you must first tick the "Active" check box. 

Here above I have setup a Periodic Action which will happen 24 hours per day at regular intervals of 10:00 minutes.  Note the a periodic Action is activated by ticking (clicking) the Active box.

I have also added in the Action macro(s) text box a Periodic Action to Capture a Screen Shot, every 10 minutes, saving it to D:\Spectrum\40M\Kapture\..

By using this method of Capture, as a screenshot Periodic Action, you can pre-name the file using the internal programming facilities of SpecLab itself.  At every interval you can command SpecLab to capture a file, by entering what you want to happen in the Action (Macros) Text Box.

I have entered the command Capture and in brackets after the command the Filename, location to save the file, the filename, and the file type (either .jpg or .bmp).

I'll explain the procedure here:
There are 3 commands in the instruction, marked in orange Text:

Capture("D:\Spectrum\40M\Kapture\Argo 40M" +str("DDMMYY hhmm",now)+"z.jpg")

Capture - tells Speclab to initiate a screen capture.

" " - Quotes deliminate text in the filename.

+  - command - "Append"

str - command that says:  the String that follows should be converted by the command now to Date/Time format.

The instruction ends up like this:

D:\Spectrum\40M\Kapture\Argo 40M 100116 2340z.jpg

The file ends up in - D:\Spectrum\40M\Kapture\

With a filename - Argo 40M 100116 2340z.jpg

At upload time ArgoUpload strips the filename back to Argo.jpg and everything happens as before!

Don't forget to do a save to your "Config" file, before you exit SpecLab!  Otherwise you will have to do this all over again....

10 Jan 2016