Paul, High Sierra Microwave has some small passband filters for the FUNcube dongle which might be of help:
http://hsmicrowave.com/FUNcube%20Dongle.html http://hsmicrowave.com/Model146M2PBPF_101011.PDF Full disclosure. I know the owner, N6GHZ though his work with AMSAT, but otherwise have no connection. 73s, Alan WA4SCA <-----Original Message----- <From: Paul Stoetzer [mailto:n...@arrl.net] <Sent: Thursday, October 03, 2013 11:02 AM <To: apbid...@mailaps.org <Cc: Alan; amsat-bb@amsat.org <Subject: Re: [amsat-bb] AMSAT Broadband Preamp Specs < <Alan, < <Thanks for the "real world" example. My receiver is an Icom IC-R10, <which the specifications say has a 0.25 uV sensitivity on 144 MHz and <0.32 uV on 435. I operate portable, so I'm not using the <preamp for the <high gain to overcome cable loss, but to overcome the relatively high <noise figure of the receiver. The preamp works great for FO-29. When I <have a clear horizon, I can hear it down to 1 degree or so <with an Arrow <antenna. My problem is the horizon (and a military spread spectrum <radiolocation system that causes "clicking" noises all over the 70cm <band here in Washington). < <On 2m, the preamp also helps greatly, but the preamp also amplifies <countless out of band signals that desense the receiver. I have a PAR <electronics notch filter to notch out the pagers at 152 MHz (two <kilowatt pager transmitters are a quarter mile away from me), but that <doesn't completely eliminate the problem. I have used a 10 dB <attenuator <between the preamp and receiver which eliminates the desense, but also <reduces the signal level a bit too much. A 6 dB attenuator <should arrive <in my mailbox shortly and I'll try it on the next pass of AO-7 this <afternoon. < <What I likely really need to add is some low loss bandpass <filtering for <2 meters, but it needs to be small since I operate with <everything in a <DSLR bag carried around my neck. Any suggestions? < <Ultimately the only perfect solution is a second FT-817 to use as the <receiver, but that's not in the cards at the moment. < <73, < <Paul, N8HM < <On 10/3/2013 11:22 AM, Alan wrote: <> Paul, <> <> Spence did some rough testing, but it was designed to be <simple, cheap, robust, and easily duplicated <> rather than cutting edge. I did some A/B testing with an <ARR preamp on SO-50 and FO-29. Both made <> significant improvement, and I did not hear any practical <difference. That would not likely be the <> case if we were talking about P3 bird at apogee. <> <> 73s, <> <> Alan <> WA4SCA <> <> <> <> <-----Original Message----- <> <From: amsat-bb-boun...@amsat.org <> <[mailto:amsat-bb-boun...@amsat.org] On Behalf Of Paul Stoetzer <> <Sent: Thursday, October 03, 2013 5:40 AM <> <To: amsat-bb@amsat.org <> <Subject: [amsat-bb] AMSAT Broadband Preamp Specs <> < <> <I was curious - has anyone measured the noise figure and gain of the <> <AMSAT Broadband Preamp? <> < <> <73, <> < <> <Paul Stoetzer, N8HM <> <Washington, DC <> <_______________________________________________ <> <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
