Matt,

You can't go wrong with the ARR P432 GasFet preamp ($79). I used one on 2m for eme until getting my current preamp. Be sure to remember that you do not transmit into it...just once and the transistor is history - no second chances.

At 11:06 PM 3/6/2007, Jonny 290 wrote:

OK, let's take a bite out of this.

RE, the preamp: I agree that it is likely a weak point. I wanted to check it out, though, and for $22 I couldn't go wrong. It'll still prove useful at some point down the road.

If one of the mast mount preamps are what the situation requires, I"m ready to take that step.

The eggbeater is actually designed with radials to 'pull' the signal towards the horizon. It almost seems as though the radials may be working too well - I've got moderate to great copy up to a few degrees, then it falls over dead. Due to my 'beater's design, it's trivial for me to replace the loops and/or the radials without messing with the phasing harness or antenna mount, so I can try an antenna that doesn't have a by-design null at high elevations. I'd almost like to do this just as a lark, as it'd cost me a grand total of $7 to go buy another 10 foot piece of 1/4" fridge tubing.

I think you may find that the antenna works much better when you get the preamp hooked there.

I can also experiment with putting the 435 eggbeater on a nonconductive PVC mast. Also a cheap experiment, couple of bucks for 15 feet of PVC. That might get it up high enough with no metal above or near it, save for the feedline.

Here's my main issue with the TV rotator, and you'll think this is silly and trivial, but it's a major sticking point, and why I've been going at this with omni antennas so far. My main mast sits _directly_ outside my roommate's window, due to overhead power line and tree location. It's the only place where I can safely have a structure above 10 feet, that is less than 75 'coax feet' from my shack window.

Mount the mast/rotator/antenna on a $33 Radio Shack tripod (Buy a 4x4 foot square of plywood to bolt the legs thru and weigh down with rocks or something heavy on three sides. I used 3 cinder blocks and the antenna survived 50-mph winds.

I'm concerned that spinning the rotator at night will bother him. If the mast is solidly mounted to the house just a few feet away, how much will one of these inexpensive TV rotators conduct into the building? Could I cut that down by putting some rubber between the mast and clamp, something of that nature?

Most LEO satellite passes last only 20-30 min. You will probably have to move the antenna about five times for a pass (max) - or computerize it. Check out WB4APR, Bob Bruninga's cheap radio shack rotator system with software (free). Very simple and cheap!

The next step, and I'm ready to move to this point if I can address the noise issue to my satisfaction, is to build a small cross yagi, 4 to 7 elements, and mount it at fixed elevation on a small TV rotator. I believe that an antenna in this size range will prove a big advantage over the omnis, should have a wide enough beamwidth such that I will get away with fixed elevation, and should only have to crank the rotator every 60 to 90 seconds, except for the extremely high angle passes.

Naw. More like every 3-5 min.

If that works on receive, but I'm having uplink problems, I can put a 2 or 3 element CP yagi for 2 meters on the same boom, which should let me hit most of the satellites with 10-15 watts of power, max.

3-elem 2m + 6-elem 70cm fits on a 3-foot boom. Google WA5VJB for simple/cheap home built yagis. Mount elements a right angles and no interaction. You have basically built an Arrow.

I'm very eager and willing to design and play with antennas - love homebrew in general, I just can't design a circuit to save my life - and know how to model and build good quality antennas. I'm fairly certain that I can get crafty enough to get around what restrictions this environment does have.

So, here's what I'm looking at, I think.

1: Mast mount preamp 2: Beam with rotator 3: Hamtronics downconverter (435.5 - 437.5 MHz, somebody tell me if I'm getting the wrong frequency range choice - my HF radio stops at exactly 30.000.000 so I want to make sure I can hit the 437+ frequencies)

The beam will require design and construction time (I don't believe in buying antennas except in rare circumstances); I can throw green paper at the preamp and get it out of the way, since store-bought is the best option for that at this time. In addition, I don't want to have to install the beam and rotator and preamp all at once; it'd be nice to have the preamp ready to go by the time I put up the beam and rotator.

Buy the preamp first! You should get it in 3-days ground-UPS.

I'll be honest, I'm generally an impatient person, and I'm busting my chops and treating this station in a rent house as a challenge. I was serious about hitting the Phase 3E sats when they go up, but I do _not_ expect to do it at my current QTH. If all comes together, I move into a house this fall, at which I hopefully will have clear space and the ability to put up a "real" antenna support. Once that happens, either a roof mount or small tower, I'll build a long yagi array and get it under computer control. But I'm not at that phase yet, and I want to get experienced at this level before I think about trying to work the high orbit satellites.

Go for a short ground mount as you will want easy access to tinker with things, often. On a pitched roof will become a pain!

I actually grew up a ham in my early teen years back in the early 90's, and remember poring endlessly over AO-13 articles. It seemed like the zenith of technical accomplishment in our hobby. I came back to ham radio last year and was disappointed to find that we had no high orbit satellites currently, but the LEO satellite 'scene' seemed active and I figured I could get my feet wet with them before I tackle the big ones when they go up.

P3E may only be a year or so off. Get started with LEO and add better antennas, later! For HEO you will need SSB, so the 435/28 xvtr is a better investment for the future. Then all you need is a 2m SSB radio. You will want 11-elem 145-MHz and 16-20 elem 435-MHz for mode-U/S. You will need a 2m preamp for that mode and at least 10w on 435-MHz (50w is better if you have a long coax run).

73, Ed - KL7UW ====================================== BP40IQ 50-MHz - 10-GHz www.kl7uw.com 144-EME: FT-847, mgf-1801, 4x-xpol-20, 185w DUBUS Magazine USA Rep [email protected] ======================================