VHF ANTENNA'S AND OTHER BITS
 

The main bands of interest are VHF with a bias towards 6M when the Solar cycle 23 was at it's best. With the fall of cycle 23 I have taken more interest in the 144MHz band again. With the rise of the current cycle 24, more interest will be shown on 50MHz. At the time of writing I have 709 WW grids squares worked and 167 DXCC entities on 50MHz. On 144MHz I have an interest in all modes of propagation, in particular, Sporadic E (Es) Meteor Scatter (MS) and "Earth Moon Earth" (EME). On 2 Metres 69 Countries and 456 WW Grid squares have been worked. 70cms is used but not in a very serious way. 83 locators and 18 countries have been worked on this band. I have only been active on 4M for a short while but at this time (2011) I have 22 DXCC countries and 68 locator squares.

I am a member of the UK Six Metre Group (UKSMG) & the Radio Society of Great Britain (RSGB)


        

                                                                                             Some of the QSL cards for 50MHz

The "Versatower" showing the VHF antenna installation. For 50MHz, 7 Element Msquared. For 432MHz, a single 19 Element Vargarda. For 144MHz, 2x12 Element Msquared in a bayed configuration are used. All fed with Andrew LDF4-50 Heliax. GaAs FET Masthead preamps are mounted at the top of the tower for both 144 and 432MHz. The lower antenna is a recent addition, 5 element yagi for the 4M (70MHz) band.

VHF EQUIPMENT

The equipment used on the VHF bands is the Icom IC 7600 for 50MHz (also used for HF) and the Kenwood TS2000 for 144MHz and 432MHz. On 144 I now run a Linear Amp UK "Discovery" amplifier with a GS35 triode PA. On 432 the TS2000 is used "barefoot". For 50MHz I use the Icom IC-PW1 Solid state PA. This runs the full UK legal output from 1.8 through to 50MHz.

     

The ICOM IC-7600 used on HF and 50MHz & the Kenwood TS2000 used on VHF.

My VHF Logs.... Have we worked on VHF? Take a look at my VHF logs for the past 5 Years. Click HERE


Linear Power Amplifiers for the 6 Metre Band

300 Watt Linear Amplifier Module.

Over the years I have had several designs for Linear Power Amplifiers published in the RSGB publication," RadCom". There are 2 designs for the 6M band and another article shows semiconductor design principles for a PA based on the 2M band. The articles for two 50MHz solid state Amplifiers are available in these pages as individual sheets or if preferred may be downloaded as 2 separate zip files. The largest of the designs is a 17 page article and unfortunately, due to the jpg format of the scanned images is 1.9MB. It covers the complete design of a 600W solid state PA for the 6M band and is very flexible as individual modules can be made, if required, to give a high performance 300W Amplifier, or if lower power is needed, the driver will provide a very high linearity 50W PA. The other design is for a single stage 100-150W Linear Amplifier for the 6M band using the same BLW96 bipolar transistor as is used in the high power design. A regulated 48V PSU is also described in this design. The complete single stage article may be downloaded as a 750KB zip file or read individually from my web pages. The choice is yours! All of these files and pages may also be accessed from the pull down menu's on the left of this page. QRZ.com will provide you with my address/email details.


VHF Meteor Scatter Propagation

Meteor Scatter is a specialised mode of propagation that relies on the reflection of VHF radio waves from the ionised trails of Meteors entering the Earths atmosphere. I have written a separate page on the subject of Meteor Scatter which you can go directly to from the "MS Page" button below. This describes some of the theory behind MS and provides links to other sites for downloading MS software. WSJT, written by K1JT is for the co/decoding of WSJT burst data transmissions. WSJT stands for “Weak Signal communication, by K1JT.” Also available is the popular software, "Compact MS-Soft for PC" written by OH5IY. This software enables the peak time for a given shower to be predicted as well as doing all the calculations for optimum MS propagation in any given direction.

The other mode used for MS contacts is High Speed CW. HSCW is generally transmitted at speeds between 1000 and 2500 letters per minute (LPM). This permits information to be obtained from very short bursts with decoding done on a digital tape recorder or similar PC based software. Unfortunately the arrival of WSJT has almost killed of the use of HSCW, a great shame, but that's progress !

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Current Solar Status Monitor

Information updated every 10 minutes
Click on the status squares for detailed graphs of current Solar Data from NOAA.
Solar X-rays:

Geomagnetic Field:
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  From n3kl.org
If you would like to listen to a CW signal that has been reflected from the Auroral curtain, then a small .MP3 file can be heard by pushing the button below. The file is only 68Kb, and is a recording of CW signals from GM4COK in a strong Auroral event. Typical Phase distortion is very evident. It can be played on almost any media player.
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Other VHF related sites of interest

Aurora Auroral oval colour pictures and lots more. More Aurora More good Aurora Information and ovals
Hamradio-online More propagation and Aurora info
Propagation Loads of propagation info including full colour Greyline map
Spaceweather Lots of Solar info and Space Weather.
U.K. Six Metre Group (UKSMG) Home page of the UKSMG
Tropospheric Ducting Forcast William Hepburn's forcast maps
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Page last updated: 17 December 2011