[amsat-bb] preamps

Michael Heim kd0ar at sbcglobal.net
Sun Aug 31 09:59:33 PDT 2008

A recent post mentioned the need for a preamp.  This reminded me of something I want to share with the group.

Station here consists of an FT-817ND and an FT-857D.  The 817 is pretty sensitive on UHF, but the 857 is a little lacking in comparison.

I was looking for a preamp online that would help, especially with the 857.  I went and ordered a Ramsey PR40.  I figured for $15 I couldnt go wrong.  Although its not a GaAs device, (its a bipolar), it works pretty well.  I actually didnt want a GaAs because I was afraid of blowing the device anyway, being I'm running a homebrew "Arrow style" antenna on a fixed elevation mast, and the 144 MHz leakage getting into the preamp would probably blow the device the first time I keyed.

I am not using any TR switching on the preamp. (I only work the FM birds at this time).  

After building the kit, I put it up, worked a pass on AO-27, then goofed and sent 432 TX energy up the line, blew the amp.  I ordered replacement transistors from MCM for $.52 each!

Although I cannot measure noise figure, it specs at 1dB, 15 dB gain.  I know it makes a HUGE difference on my end.  Satellites that were noisy before are now full quieting and armchair copy

I have found this item a very cost effective solution.  I wanted to share this experience with the group.  I'm just pleased with the preamp and of course, receive no personal gain by recommending this product.

 Michael Heim

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