[amsat-bb] What preamp to use for SO-50 and Arrow II antenna?

[Dominic Hawken]

The inaugural edition of Radcom Plus came out today, and the first article is on building a 2m masthead preamp - the DG8. I don't think it's particularly appropriate for handheld use, but looks interesting in that it uses (cheaper) mains relays - whilst I've only had a brief scan the article looks really well written and detailed. I've been looking for a cheaper masthead option for 2m to build and so far the relays have always been the significant cost. Power to this one is also over the coax, so it suits me well.

Radcom Plus is available online for RSGB members - http://rsgb.org/main/blog/front-page-news/2015/04/30/radcom-plus-vol-1-1/

No - I don't work for the RSGB - just genuinely impressed!

Best,

Dominic G6NQO


> On 1 May 2015, at 05:09, John Brier <johnbrier at gmail.com> wrote:
> 
> Thanks, I found that at their website:
> 
> http://www.hsmicrowave.com/Amateur%20LNA.html
> 
> I'm going to use two radios so that won't be an issue.
> 
> Man, so they do require power, or at least this one does.
> 
> I'm already starting to get tired of trying to track the satellites
> with the Arrow II. Adding a preamp with a battery pack and a second
> radio (I've mostly just been listening to the ISS lately) is going to
> get even more cumbersome, plus you have to operate two radios while
> compensating for doppler, right? How do you operate portably with your
> FT-817s? Do you attach one to each hip?! I'm starting to think about
> circularly polarized antennas I can just set and forget, but with a
> low power satellite like SO-50 that might not work so well. Hmm.
> 
> 
> 
>> On Fri, May 1, 2015 at 12:00 AM, Paul Stoetzer <n8hm at arrl.net> wrote:
>> I use a High Sierra Microwave LNAA432 preamp powered by a 11.1v LiPo
>> battery pack (AAs or AAAs work fine too). I can work SO-50 down to the
>> horizon with the Arrow Antenna if I have a clear shot. I lost at about
>> a degree on the pass earlier. It's usually S1-2 below a couple of
>> degrees, S7 above 10 degrees, and my FT-817 shows S+ above 30 degrees
>> or so.
>> 
>> You have to be careful not to transmit into a receive only preamp like
>> this. I use two FT-817s, one for receive and one for transmit, so this
>> is not a problem for me, but if you use a single radio, you would need
>> to be sure that the preamp is between the 70cm antenna connection and
>> the diplexer so you don't fry it.
>> 
>> 73,
>> 
>> Paul, N8HM
>> 
>>> On Thu, Apr 30, 2015 at 11:49 PM, John Brier <johnbrier at gmail.com> wrote:
>>> Since a lot of people are talking about SO-50 right now, let me ask a question:
>>> 
>>> I did try to work SO-50 once when all I had ever worked before was
>>> SO-35, UO-14 and AO-27 and I was horrified by how hard it was to hear
>>> and track.
>>> 
>>> I found a thread on qrz.com where they said it's very helpful to use a
>>> preamp for SO-50 since it's so low power, even with the short runs of
>>> coax required for an Arrow II satellite antenna. I know almost nothing
>>> about preamps. What's the deal? Do they need power to work
>>> (active/passive?). What do you recommend?
>>> 
>>> John Brier, KG4AKV, Raleigh, NC, FM05
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> _______________________________________________
> Sent via AMSAT-BB at amsat.org. AMSAT-NA makes this open forum available
> to all interested persons worldwide without requiring membership. Opinions expressed
> are solely those of the author, and do not reflect the official views of AMSAT-NA.
> Not an AMSAT-NA member? Join now to support the amateur satellite program!
> Subscription settings: http://www.amsat.org/mailman/listinfo/amsat-bb