Sunday, December 23, 2012

HPSDR on 70MHz WSPR again

Overnight I remembered that it is possible to control the HPSDR under Cat control. It can emulate the TS-2000. So I went into HPSDR setup and changed Cat control to 4800-N-2 on COM17  and enabled it:-


In the WSPR program under station parameters PTT method was changed to CAT, enable cat was ticked and Kenwood TS-2000 4800-8-N-2, no handshake chosen:-


Remember N8VB VCOM previously set up a virtual com cable between com7 and com17
Now the HPSDR is controlled without DTR etc. WSJT can also control the frequency.
Efforts were rewarded. My signals were heard in Holland:-

 2012-12-23 19:12  G4FRE  70.092501  -23  -1  IO82uc  5  PA0O  JO33hg  614  74 
 2012-12-23 16:08  G4FRE  70.092507  -17  -2  IO82uc  5  PA0O  JO33hg  614  74 
 2012-12-23 14:56  G4FRE  70.092474  -16  -1  IO82uc  5  PA0O  JO33hg  614  74 
 2012-12-23 14:22  G4FRE  70.092485  -18  -3  IO82uc  5  PA0O  JO33hg  614  74 

And in the UK:-

 2012-12-23 15:54  G4FRE  70.092522  -20  0  IO82uc  5  G3SHK  IO90dx  131  162 










 2012-12-23 12:00  G4FRE  70.092501  -25  -1  IO82uc  5  G0MJI  IO83ni  144  344 
 2012-12-23 10:32  G4FRE  70.092521  +12  1  IO82uc  5  G3LVP  IO81wv  26  154 
 2012-12-23 09:24  G4FRE  70.092451  -15  3  IO82uc  5  M0NKA  IO92  95  63 


And I heard a signal from Holland:-


 2012-12-23 14:02  PA0O  70.092501  -30  -1  JO33hg  50  G4FRE  IO82uc  614  261

Saturday, December 22, 2012

HPSDR on 70MHz WSPR

Tonight I decided it was time to work out how to interface the HPSDR to the K1JT WSPR programme and try it on 70MHz. My Penelope board has a -20dB coupler on the output giving 0dBm which is fine for driving my DEMI L70-28 transverter http://downeastmicrowave.com/PDF/VHF-UHFXVERT_pd.pdf (serial number 1!) to 35W maximum. The normal 0.5W output of the Penny board should be terminated in 50 ohms to protect the output stage

I use the W5WC dual RX version of POWERSDR as this allows me two 96kHz chunks of the band to be seen at the same time. Usually one is on the beacons and one is on the calling channel
First I installed my paid for copy of Virtual audio cable which will allow the audio to be connected between the 2 programmes. It was configured to support VAC1 and VAC2.
Next a copy of N8VB's VCOM programme was installed with 2 pairs of cables, COM6>COM16 and COM 7>COM17
In the HPSDR Setup, CAT control TAB the port is set to COM 16, RTS and enabled:-  


Next the VAC setup in HPSDR. VAC1 is setup as VAC2 as the input and VAC1 as the output:-

Next the WSPR programme needed setting. Audio IN is set to VAC1 and audio OUT is set to VAC2. Note these settings are the REVERSE of the HPSDR ones


Drive level to the transverter was set to produce 5W output. The 10MHz reference for the HPSDR was produced by a Thunderbolt GPS unit,  which also, with the help of KE5FX "Lady Heather" Monitoring programme http://www.ke5fx.com/heather/readme.htm was used to set the computer clock every 15 minutes. The 70/28MHz transverter Local Oscillator is not yet GPS locked; an upcoming project based on the G4HUP DFS design

The system was allowed to run whilst packing the Christmas Candy

Looking at the WSPRNET spot database http://wsprnet.org/drupal/wsprnet/spots it was pleasing to see the signal had been seen:-

 2012-12-22 22:16  G4FRE  70.092565  -15  0  IO82uc  5  M0NKA  IO92  95  63 
 2012-12-22 22:16  G4FRE  70.092534  -22  -1  IO82uc  5  PA0TBR  JO22pi  517  84


The PA0BTR spot was the ODX for the days spots on 4m; not bad for my Indoor Halo!

Sunday, December 16, 2012

ADS-B using the R820T USB Dongle and VirtualRadar

Having managed to produce the Data I also wanted to try displaying it with virtual radar. This is available from http://www.virtualradarserver.co.uk/  To use it with ADSB# server some parameters have to be changed under options. Data source to "AVR or Beast raw feed", Address to 127.0.0.1 and port to 47806

Start ADSB# first 


then Start Virtual radar which will show incoming activity


To see the data in map format click on the link to http://127.0.0.1:VirtualRadar. The following is the map after running for a few hours showing the airplane tracks; not surprisingly all to the east of me. Currently 39 planes are being tracked:-


Looking back at the virtualradar window the above "connection" can now be seen listed:-


Comparing the plots produced by the same data using Virtualradar and PlanePlotter Planeplotter captures more planes, but it is not free! 

ADS-B using the R820T USB Dongle and PlanePlotter

G4VXE recently alerted me to software capable of producing ADS-B data under windowshttp://sdrsharp.com/index.php/a-simple-and-cheap-ads-b-receiver-using-rtl-sdr. I downloaded the executable and after installing the R820T driver using Zadiq from http://rtlsdr.org/softwarewindows we were in business. Connecting the homebrew 1090MHz colinear on the window ledge data packets were being produced.


Note that the driver only needs installing once, not as some have tried after every reboot

Next we needed something to display the data

I already had the paid for planeplotter installed on the computer so I would try that first. A couple of changes to the setup used with the Modesbeast were needed. The mode S receiver option needs setting to "AVR receiver"


The IP address and port then needs to be set:-



Finally the input/output settings need to be set to AVR receiver TCP


Planeplotter was started and left running for 6 hours:-



Not as good as the ModeSbeast but very good for the price of the USB dongle.

Friday, December 14, 2012

Hermes as a VNA: Reflection

Next task was to look at filter return loss. In addition to hermes one needs a reflection bridge. This has a port for RF input, a port for reflected output and a port to connect the device under test. Looking in the RF goodies box I found a commercial Wiltron 80NF50 5MHz to 2GHz SWR bridge which would be ideal. To try it out a filter in the 0.005-2Ghz HF bands was needed so looking in the MW2I contest parts box I found one of the two W3NQN bandpass filter box that was built on the PCB from 5B4AGN and decided to test the 15m filter
To make sure it still worked i first configured the system for transmission measuring 3 to 30MHz as described yesterday. The results were as follows:-



Which showed it still worked. Next the system was configured for return loss. The Hermes transmit output was connected through the 6dB attenuator to the bridge RF input. The Reflected RF output from the bridge was connected to the receiver input of Hermes. The device under test port was left open circuit. The software mode was changed to reflection chart , It was time to calibrate.
For return loss a calibrated open circuit, short circuit and 50 ohm load are needed. I had purchased a suitable set from SDR-Kits with SMA male connectors so these were used, being attached as prompted by the software.
The filter box, terminated in a 50 ohm load  was then connected to the device under test port and the following measurement produced:-


This showed that the filter had around 20dB return loss over the whole of 15m. To expand the vertical scale I clicked the "auto range" button under "display":-
 To further expand the horizontal axis the start and stop frequency boxes under the plot were changed to 15 and 25MHz:-

This showed how good the return loss was. Obviously it is still working fine.
All results (measurements AND calibrations) can be saved to disc to allow later use.

Thursday, December 13, 2012

Hermes as a VNA: Transmission

Tonight I found a short time to try out the VK6APH VNA code to use my Hermes Board/ANAN  10 as a VNA.  

As suggested in the V1.9 user manual I put a 6dB attenuator on the Hermes TX output to define the source impedance for measurements as 50 ohms

First I connected the TX output through the 6dB attenuator to the RX input and carried out the calibration routine. Just to check it had worked alright, i left the connection in place and hit the measure button, which resulted in the following result


Which is what I expected to see

Next I needed a filter to measure. The first filter that I found was my LF lowpass filter that I used in front of the SDRIQ to keep high power MW stations out of the front end while listening to 136 and 500kHz. This was connected between the TX and RX ports of Hermes still with the 6dB attenuator in circuit. The result is as follows:-

When I can find the necessary adaptor cables, the next task is to use a reflection bridge to measure return loss


The KX3, the fridge and the hairdryer

In my post on Jul 7 2012 I noted that frequency stability of the KX3 was not good enough for digital modes even on 40m. It had been pointed out that the KX3 was designed as a portable mountain top rig for use on SSB and CW and it was never designed to be highly stable

Since that time Wayne N6KR has done some investigation and has come up with a procedure to generate a custom frequency offset versus temperature table for the KX3 that the KX3 can use to adjust the offset. The procedure is at http://www.elecraft.com/manual/KX3%20Custom%20VFO%20TC%20rev%20A8.pdf

To do the procedure,  a highly stable (the XG3 isnt good enough!) 50MHz signal source is needed. Elecraft will sell you a suitable XG50 for the purpose but there has to be something in the shack. The K3 runs off a GPS locked 10MHz source so the fifth harmonic could be used? Initial tests showed the 50MHz level was not high enough, I needed a harmonic generator. Searching the parts bin I found an LF minicircuits mixer with connectors (intended for my 477kHz TRUE transverter). These contain diodes so they must generate harmonics. I found that driving the IF port with 10MHz and connecting the RF port to my 6m antenna produced a healthy 50MHz signal. good enough for the procedure

After making sure that I understood the procedure the KX3 was put in the fridge for 30 minutes. When removed the KX3 starts to warm up and the KX3 records the audio frequency of the tone against temperature (actually temperature a to d value...you can see what is happening in the KX3 utility programme as well as on the KX3 LCD) and stores it. To calibrate the upper temperature range (above KX3 ambient temperature) a hairdryer is used to heat it up. The procedure suggests until 52C but, being winter mine stopped at 43C which is adequate for the UK so I stopped calibration there.

After applying the calibration table It was great to hear the note of the 50MHz signal stay at around 550Hz all the way back down to 25C. The process was speeded up by putting the KX3 on a bag of frozen peas!

Next to see what the KX3 looks like on LF QRSS


Wednesday, December 5, 2012

KX3 Maintenance

Time to take the KX3 apart and address a couple of issues

I finally got hold of the KXBC3 Battery charger/Real time clock that was ordered Dec 28 2011 (11 months!). Took about 30 minutes to fit. Now I do not have to take the batteries out of the case to recharge them, but there is enough backup power on the board for the clock to remember the time for up to 5 minutes if the batteries are taken out.

While it was apart I took out the RF board to do the upgrade to take care of the lower dynamic range on 80/160m that was identified in the ARRL QST KX3 review. This involves removing 4 surface mount Inductors and replacing them with different values. The Inductors cost under $1 from Mouser Electronics. The modification took just 30 minutes. For the squeamish you can get Elecraft to do the changes for you  for $50 plus shipping each way as they consider it an "improvement" not a "defect correction"

Next I will do the extended temperature frequency calibration procedure to see if I can make it work on HF QRSS/WSPR without drifting. Fortunately this has to be done with the covers on