Sunday, 16 July 2017

WSPR spots while using dummy load

QRP-LABS U3 1Watt into dummy load
Having destroyed the BS170 FET in my QRP LABS U3 I decided to press a small driver amp I'd made into service instead of replacing it.  Wasn't sure what power out I would get and was pleasantly surprised with the easy 1 Watt it produced driven directly by the  Si5351A synthesiser.  The driver was running in class A so no easy way to turn the power out down but nevertheless I decided to soak test and left the U3 running into a dummy load for several hours.  Really don't know why I decided to check WSPRnet for spots and was amazed when several came back.  As you can see in the photo nothing was screened. Perhaps there is a warning there for the next time I start whistling into a dummy load
The spots I received

Sunday, 4 June 2017

Pskreporter and DX

Don't you just love PSKreporter, tells you all the DX you've missed while your out and about. Here's what my radio received today on Six. Best of the bunch A6VQ TY2AC AB1NJ. Oh well, most likely wouldn't have worked them anyway.

Friday, 23 December 2016

Successful EME contacts

Massive EME array?  8 element DK7ZB
 Success

After several weeks of trying I finally got lucky and had two QSOs via EME.  Below are several screen shots from the contacts. The only thing that was different this time was the antenna. I used my 8 element DK7ZB instead of the thirty year old 9 element Tonna.  The Tonna is showing signs of it's age and I'm wondering if the corrosion is affecting it's gain.

Equipment

Modified Kenwood TM255E (SI570 LO, IF tap)
Homebrew SDR tuned to TM255E IF
Homebrew 300 Watt amp (Freescale MRFE6VP6300 mosfet)
8 element DK7ZB  (gain 12 dBd)
Software;
WSJT-X v1.7.0-rc2
PowerSDR-IQ


So I'm pretty happy with that and looking forward to more contacts.

Transmitting RO
Completed QSO
The second contact was an answer to my CQ, pretty suprised I can say
Second contact
And a card

Saturday, 5 November 2016

EME, to the Moon

 Inspiration

It's the ultimate challenge of amateur radio, Earth-Moon-Earth also known as moon bounce but is it possible with a small station like mine? Until recently I would have said no but after using MAP65 from K1JT I'm starting to think that maybe it is possible.
I've been using SDRs for some time now on VHF, so I already had available the IQ output needed to use MAP65.  This allows the decoding of all JT65B signals within a 90kHz bandwidth.  I've used the software to monitor beacons on Two with good success, at times being able to decode four beacons at the same time, GB3WGI, GB3NGI, GB3VHF and F5ZRB. But it never occurred to me to try and hear anything off the Moon. That was until one evening while watching an art programme an item appeared about artist Katie Patterson's Earth- Moon - Earth.




Katie used EME to record Beethoven's Moonlight sonata complete with gaps due to fading and then replayed it on a modern player piano. This romantic idea of radio waves going to the Moon and back was an inspiration so I started reading all about EME. I soon discovered that with JT65B, on Two, small stations were having success with single yagis and no elevation.

 Help needed


Ground gain or in this case sea gain


Apparently, EME is possible with 100 Watts and a single Yagi using JT65B.  It is often achieved at Moonrise or as the Moon is setting when ground gain is available.  I took this photo of the Moon over the sea a while ago and if I've got this right it should help to illustrate the principle.  Light from the Moon is taking two paths to the viewer, direct and that reflected from the surface of the sea. The reflected light adds to the overall illumination. In radio that can add as much as 6db to the signal at 144 MHz.  There's much more about ground gain online as a search will reveal but it's just like having four Yagis, not just one. Of course, it's only available when to Moon is at low angles as in the photo. ↗

 First monitoring


So with this in mind, I started to monitor off the Moon. Pointing my small 9 element beam towards Moonrise I left MAP65 running overnight.  Moonrise would occur in the early hours so I wouldn't know if anything had been received until the following morning. Come morning there was just one line in the band map, "73", time, signal strength, etc.  So to see if anything else had been received I opened up the text file Map65-rx found inside the MAP65 folder.  It contained all decoded data received through the night and to my amazement several stations had been received, two Russians and an Italian. Pretty encouraging but I had in the past, while monitoring beacons, seen false decodes so to be sure I turned off the Deep Search and renamed the CALL_3 file to be sure that I was indeed hearing off the Moon.
Once again I pointed the beam towards Moonrise, left MAP65 running and waited to see what might be decoded with the Deep Search disabled.   Once again there were several stations decoded and this time they could not be false decodes.


 More monitoring

 

 Over the following weeks, I continued to monitor and I soon started to realize that signals could be heard from Moon elevations of just 1 degree to as high as 25.  Outside this range decodes are few and far between but they did occur even 1 degree below the horizon on one occasion and at 60 degrees above.

Next.......

 I've improved receive performance by building a new preamp.  I'm looking very carefully at the transmitted signal as getting audio harmonics to a low level seems important to me. I need to familiarize myself with the operation of WSJT JT65B. Just monitoring is easy but TXing is going to be more demanding. I need to test my amp at the high duty cycle of JT65B........etc...etc....... but hopefully I'll soon be ready for that first contact.  I'll post here if I make it.

Cheers & beers

Dave G8TTI

UPDATE
15/12/2016
Well, I keep trying but not had much luck so far.  Was spotted on Livecq by a Dutch station but can't help wonder if that was tropo.  Also had a QRZ, well I think it was for me.  I'll just have to keep trying. Amp works fine and I have a 12dBd antenna to try, hopefully, that will help.
73


Saturday, 24 September 2016

G3VRE Mini Rally

Rally was a great success and will return in 2017

NOTE POST CODE SHOULD BE SN15 5NJ

Friday, 16 September 2016

Some success with 1296MHz WSPR

Had some success with 23cms WSPR but found that transmit with my old transverter will not work as there is far to much drift even tough I've ovenized the LO.  Needs more work on the oven.