[VHFcontesting] Pre-amp questions

[Harry Brown]

Jeff and Mike,

For contesting obviously more power gets you the contact in the least 
amount of time however until you get amps, don't despair. I was at Joe, 
K1JT's house a year or so ago and he demonstrated WSJT off  the moon on the 
horizon. He was operating with 4 small 7 element beams and received echos 
off of the moon running somewhere around 40 watts out. More power and no 
ground gain certainly would be better but you should have fun even with low 
power.

Use the largest coax you can scrounge.

73, Harry, W3IIT

At 06:06 PM 7/25/2004 -0400, jeff millar wrote:
>I made some different choices on my 90 Ft Rohn 25 tower
>
>Most important, bought a house on a hill overlooking a vally in my primary 
>direction (SSW)
>
>Tied off the top guy 10 ft below the top of the tower to leave room for H 
>frames with antennas below the top
>Placed the tower against the house, short run for feedlines straight into 
>the shack.
>Feed lines come in through 6 inch PVC pipe through hole drilled in 
>wall.  Enter at ceiling of basement shack
>House mount bracket at first point where guys would go.
>
>Water  got into rotor cable at top and ran down though cable and poured 
>out over shack table, had to put a drip hole in the sheath.
>
>Plan on stacking 432, 1296 antennas vertically using H frame
>
>M2 5 elements on 50, decided against 7 el due to wind load
>Cushcraft 13B2 on 144, upgrading to M2 this summerSurplus 7/8  or 1/2 inch 
>heliax for all feedlines
>Homemade FO22 on 432
>
>Surplus 7/8  or 1/2 inch heliax for all feedlines
>Separate feedlines for each antenna, no preamps (yet)
>Preamps create lots of failure modes and introduce connector and jumper loss
>Preamps fail a lot due to lightingSurplus 7/8  or 1/2 inch heliax for all 
>feedlines
>Big used  coax seemed like a better choice than complex preamps
>
>With good feedline, preamps on 50 , 144, and 222 MHz just hurt the dynamic 
>range
>Preamp on 432 would probably help a bit, but the station preforms just as 
>well as the 144 under most propagation
>
>Running the rig barefoot clearly puts me at a disadvantage.  Can't work 
>WSJT, can't work the weak big gun stations
>Will add an 700-1500 Watt amplifier before adding preamps
>Antennas may not take take 1500W...need to power divide and stack them
>
>hope this helps...
>
>jeff, wa1hco
>
>Michael A. Urich wrote:
>
>>In approximately a year or so, we are selling and moving out into the
>>country where I can grow steel and aluminum.  I am not going to have the
>>problem of being burdened with too much money, so like many radio
>>projects, putting a station on the air is going to have to be done in
>>stages.  The trees where we are looking at land are in range of 70-80'
>>tall so the first order of business is a good tall tower. I'm considering
>>going up with a 100' Rohn 45G tower.
>>
>>The rig in use will be my Yaesu FT-736r equipped with 50/144/222/430
>>bands.  And at the moment my antenna choices are:
>>50 MHz = C3i C7-50
>>144MHz = C3i FO 15-144
>>222 MHz = C3i FO16-222
>>432 MHz = C3i FO22-432
>>
>>My vision is to run a single LMR-600 feedline to the top of the tower and
>>then switch it to masthead pre-amps with LMR-400 runs to the antennas.  I
>>intend to use a NEC weatherproof box at the top of the tower for the
>>pre-amps and switch. The LRM-600 will terminate in the shack into another
>>switch with LMR240 going to the four modules of my FT-736.  Somewhere in
>>the future I will be adding RF amps for each band as the $$$ permit.
>>
>>My question is, have any of you, or do you know of anyone who has tackled
>>a similar project?  I am also looking for suggestions on mast head antenna
>>switching and recommendations for pre-amps.  I'm also wanting ideas for
>>lightening protection area as well.
>>
>>Mike Urich, KA5CVH
>>www.ka5cvh.com
>>
>>Mike Urich, KA5CVH
>>www.ka5cvh.com
>>
>>Mike Urich, KA5CVH
>>www.ka5cvh.com
>>
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>>
>>
>
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