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

Saturday, 7 November 2015

U3S Beacon Kit

I have spent a couple of days modifying my U3S, and tidying up the wiring to make it look presentable inside the case.  I also used the spare panel switch to switch the power to the amplifier on and off.


As built from the Kit Instructions, and powered by a single 5V supply, the U3S will change frequency, when transmitting a Callsign or WSPR Frame.  Or indeed any other mode of transmission.  This can be quite problematic on WSPR as it can cause the receiver to fail to decode an otherwise good signal, due to excessive Drift.  On QRSS it causes an ugly 'sag' in the frequency, which has been likened to Bow's or Hook's.
After hearing about WA5DJJ's problem of Bow’s at full power and when he decreased the power output, the Bow’s decreased.  Bow's are frequency shifts caused when the U3S is transmitting, it occurs on WSPR, and QRSS.  These shifts look like bows or hooks on a 4 hour QRSS Grabber image.  I remembered my earlier tests when setting up the OCXO/Si5351, without any voltage on the amplifier, there were no Bow’s.  On analysis, this led me to believe the problem lay with RF from the Amplifier being fed back into the OCXO and causing frequency shifts, via the common 5V supply rail.  In fact that is how I frequency lock my IC-R75 receiver!  Fortunately the 3 supply rails can be easily separated (it is a feature of G0UPL's design), by simply removing 2 links installed at assembly time.

This is how I did it:

1.    I added three L7805CV, TO220 cased voltage regulators, inside the case to minimize voltage drops in the supply leads to the equipment itself.  See photographs below.
2.    The 7805’s are bolted to the inside of the lower outer-case half, and in a line just under the front edge of the installed GPS.  My GPS board is mounted component side up.  I use an external 3V3 amplified Antenna, not the supplied patch antenna.  The supplied antenna wont work inside the aluminium case!
3.    There is no need for an insulating washer under the mounting screw or a mica washer under the 7805 case; the cases are grounded, anyway. 
4.    Each 7805 has a 33µF 50V Tantalum capacitor directly across its input and ground, and a 0.1µF 100V Mylar capacitor directly across its output and ground.  Each capacitor is soldered onto the leads of the 7805’s to minimize lead inductance.

5.    The capacitors across the terminals of the Regulators are essential to stop the RF getting back into the other supply rails, and indeed into the Regulators themselves. No other bypass capacitors are required.

The three, 7805 Regulators feed:

1.    The Amplifier (PA) – but could be exchanged for a 7809 or 7812 as the need arises.
2.    The Logic Board and OCXO (+5 Volt rail).
3.    The OCXO Oven Heater (Heat).
To feed these three sections separately, remove the 2 links adjacent to C1 on the main board.  One connects the PA to the +5V rail and the other connects the Oven Heater to the +5V rail.  I installed a 4 way plug on the outer row of holes in the main board marked +PA/+5V/Heat/Gnd.  I added a 5th wire to the loom which is connected to the Filter/Relay board ground plane, and the 2 earth wires are connected to a common earth point at the 3 Regulators.  The 3 regulators are bonded by their mounting screws to the case bottom half.
I installed a couple of Ferrite beads over the 5 wire supply cable (just in case) where it is routed over the top of the Display, the beads (and cable) push neatly into the gap between the Panel Facia and the Display board.  
I’m currently using a mains power supply whose output is 12V; it is capable of 10 amps, but a supply that is capable of 2 amps would be entirely adequate.  The output voltage is 12V, and it does not change when running 250 mW from the U3S.  
Soak testing the unit today I have found there is minimal temperature rise from any 1 of the three 7805’s used, even when using the 12V supply.  It will remain there.
I am very pleasantly surprised!  The U3S no longer displays any tendency to cause Bow’s, Hooks, or what-ever you want to call them.  The output frequency remains constant for the whole 7 minutes it takes to send my call, and restarts at the same frequency every time.  Even when running full power.  The PA can be switched on/off/on while it is transmitting and the unit will not reset, a problem I discovered when using a common supply rail!  
Photos of the 'guts' below.  I hope this answers a few problems and you find it useful.

Pete Mulhare

Click to enlarge

Side view

Top view

Case - Radio & GPS removed
View showing, three 7805 5V regulators and associated wiring.
MCX to SMA GPS external Antenna connector and lead.
SMA to BNC HF Antenna Connector and lead.

Sunday, 1 November 2015

40 Metre Band QRSS Frequencies

There is a major problem with the current QRSS slot on 40 metres.  Here in the South West Pacific, after dark we have huge amounts of USB phone signals on 7000.0kHz coming from Asia which are pirating the International Amateur Bands.  These signals have become so intrusive that they completely obliterate the The QRSS Groups low power signals entirely.

I propose that as a group the QRSS Knights Group 'move house' to a quieter part of the band.  It would be convenient to be just below the WSPR Band on 40 metres as the Group does the same on 30 metres.  The likelihood of mutual interference is small and short term and like we do on 30 metres, it can be largely ignored.  This portion of the band is usually reasonably quiet.

Old QRSS Frequencies:
7000.700kHz ---7000.800kHz----7000.900kHz

Proposed QRSS Frequencies: 

For comparison WSPR frequencies are:

I have recently had discussions with Bill Houghton W4HBK regarding this problem and he is saying that he is having the same problem, with pirate SSB signals emanating from the Caribbean area, and he also agrees that a change is necessary.

4 hour Grab showing QRM starting 0700UTC

Since the troubles in the Middle East have escalated, there are now a number of OTHR's using this area of the band for surveillance purposes, and they are adding to the problem as well.  The sooner the change is agreed to the better for our hobby in the long term.

Pete Mulhare