[amsat-bb] Masthead RF preamp suggestions?

[Stephen E. Belter]

Ken,

Highly directional antennas will outperform omni antennas by a significant margin, assuming you're using azimuth and elevation rotors.  Not only are you getting a much stronger signal from the satellite, you're attenuating the noise from all directions except where you're pointing.

To try to measure the difference, I've been comparing the number of packets of telemetry I can decode from the Fox satellites using omni antennas vs. steered directional antennas.  All of the antennas used mast-mounted preamps (SSB-Electronic GmbH, www.ssb.de) and FUNcube Pro-Plus receivers.  The directional antenna system typically copies 5-7 times as many packets as the omnis.

You didn't specify your application:  Are you only planning to *listen* to satellites, or are you building a transmit/receive station?

If you are building a transmit/receive station, you'll also want a preamp that has RF transmit detection and automatic switching (from transmit to receive).  You'll also want a preamp with good front-end filtering to reduce the impact of the transmitter on the received signal.

I agree completely with putting the preamp at the masthead.  The role the preamp usually plays is to overcome the loss of the coax from the preamp to the radio and to improve the sensitivity of a deaf radio.  If your radio has good sensitivity and the coax run is less than 3 meters, a preamp won't help or won't help much.

Unfortunately, a preamp with automatic RF switching and good front-end filtering isn't reasonably low-cost.  If you're building a listen-only station, you can get much less expensive preamps that work well.

I've had very good luck with the SSB-Electronic GmbH preamps sold by www.ssbusa.com in the United States.  Since you are in Canada, you may want to go directly to the factory in Germany.  The SSB preamps come in a weatherproof case.  

Advanced Receiver Research (ARR, www.advancedreceiver.com) has less expensive preamps that are also popular, but you'll need to build the weatherproof housing.  The front-end filtering isn't as good as the SSB.

Good luck!

73, Steve N9IP
--
Steve Belter, seb at wintek.com

On 1/24/19, 7:33 AM, "AMSAT-BB on behalf of Ken M" <amsat-bb-bounces at amsat.org on behalf of va7kbm at outlook.com> wrote:

    Hello all,
    
    I am seeking suggestions for reasonably low-cost (but reasonably effective) masthead preamps for 2m and 70cm to go along with a pair of omni QFH antennas. Kit or commercial is fine.
    
    Also any thoughts on how effective preamps might be on omni antennas vs highly directional antennas.
    
    Thanks -
    
    73 Ken VA7KBM
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