Indeed....a preamp can be a good thing. I own one myself. But, in my current location, a preamp is causing too much compression and I end up with lots of unwanted noise and other products that make it worse. It is true that I get a good amplification of the received signal, but the total, overall result is worse. Sigh.....the term location, location, location is so true. I overlook the city of Frankfurt, Germany and there is simply too much high power RF that gets sucked into my amp, along with the signals I do want.
I have a WACCOM cavity filter for both VHF and UHF that I'd like to use at the mast head, but they are too big to get up there (and they are not weather proof). Oh, and they are only a couple dozen KHz wide, which makes tuning to a different frequency a bummer.
My moral, if it works, by all means do it. But from my experience, attenuation is just as valuable as amplification. It all depends on your individual situation. Maximum gain doesn't always mean maximum useable signal. Maximum total system noise figure can be a bit daunting to achieve. I sometimes need to keep reminding myself that this is only a hobby and I am getting way too serious!!
Gary, N7BRJ/DA1BRJ
-----Original Message----- From: amsat-bb-bounces@amsat.org [mailto:amsat-bb-bounces@amsat.org] On Behalf Of Jim Jerzycke Sent: Tuesday, September 18, 2007 6:26 AM To: Bob Stewart; Amsat-BB Subject: [amsat-bb] Re: New Preamp
Welcome to the wonderful world of mast-mounted preamps! 90% of the people who get involved with satellites (INCLUDING myself) think they don't *need* a preamp. After doing all you can (better antenna, lower loss feedline, etc) to get your receive setup maxed out, you finally decide to "just try one; I can always sell it on eBay", and are usually amazed at the improvement it gives you. The _first_ thing I suggest to newcomers is to buy a good preamp. Sadly, most are like I was, and stumble around for weeks or months worrying about other things before finally buying one. Congrats, and enjoy your preamp! 73, Jim KQ6EA
--- Bob Stewart bob@evoria.net wrote:
My new 70cm preamp came in today! I got the ARR mast-mount version. I wasn't sure I'd hear any improvement, but it's very noticeable. I was able to hear QSOs on SO-50 down to about 15 degrees tonight, whereas before, 20 was really stretching. I am using a turnstile in the attic with reflector elements at about 9.25" below the radiators. I can see that I'm eventually going to have to build more robust versions of my turnstiles and put them on top of the roof.
My power supply is a bit odd, so maybe someone will get a kick out of it. I have an Atlas 210X left over from years ago, and the PSU will power either of my bricks. The 210X slides into the PSU which an SO-239 on the back of it. In order to get the power up to the preamp, I added a fused switchbox and sent the power through that SO-239. This allowed me to just screw on a Radio Shack 50 ft length of RG-58 without having to cobble up a connector on the rig end.
Bob - AE6RV _______________________________________________ Sent via AMSAT-BB@amsat.org. Opinions expressed are those of the author. Not an AMSAT-NA member? Join now to support the amateur satellite program! Subscription settings: http://amsat.org/mailman/listinfo/amsat-bb
_______________________________________________ Sent via AMSAT-BB@amsat.org. Opinions expressed are those of the author. Not an AMSAT-NA member? Join now to support the amateur satellite program! Subscription settings: http://amsat.org/mailman/listinfo/amsat-bb