VHF ANTENNA'S AND OTHER
Some of the QSL cards for 50MHz
"Versatower" showing the VHF antenna installation. For 50MHz, 7 Element Msquared. For 432MHz, a single 23 Element Flexa. For 144MHz, 2x12 Element Msquared in a bayed configuration are used. All fed with Andrew LDF4-50 Heliax. Phempt 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.
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.
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
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Other VHF related sites of interest