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

Discussion:

John Brier

2015-05-01 03:49:11 UTC

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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Paul Stoetzer

2015-05-01 04:00:12 UTC

Permalink

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

Post by John Brier
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
_______________________________________________
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

_______________________________________________
Sent via AMSAT-***@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.
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John Brier

2015-05-01 04:09:17 UTC

Permalink

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.

Post by Paul Stoetzer
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

Dominic Hawken

2015-05-01 11:23:32 UTC

Permalink

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

Post by John Brier
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.

_______________________________________________
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

R.T.Liddy

2015-05-01 16:33:09 UTC

Permalink

John,
No doubt a pre-amp would help immensely. However, I don't useone when portable since my feedline is less than 10 feet long. Themore important thing is to be able to change your polarity to matchthat of the Satellite. Mismatched polarity can degrade the signal bymore than 20 dB. I seldom have trouble hearing SO-50 as long asI keep up with the tumbling of the bird.
73/GL, Bob K8BL
From: John Brier <***@gmail.com>
To: AMSAT BB <amsat-***@amsat.org>
Sent: Thursday, April 30, 2015 11:49 PM
Subject: [amsat-bb] What preamp to use for SO-50 and Arrow II antenna?

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
_______________________________________________
Sent via AMSAT-***@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

_______________________________________________
Sent via AMSAT-***@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: h

Steve Kristoff

2015-05-01 16:42:42 UTC

Permalink

I'm a complete rookie at this, so take it for what it's worth, but I must
agree with Bob K8BL. I use an Arrow antenna and the reception is usually
59+ if you have the antenna pointed AND tilted (for polarity) in the right
direction. On low angles, reception can go from 59 to null just by rotating
the antenna 90 degrees.

Steve AI9IN

Post by R.T.Liddy
John,
No doubt a pre-amp would help immensely. However, I don't useone when
portable since my feedline is less than 10 feet long. Themore important
thing is to be able to change your polarity to matchthat of the Satellite.
Mismatched polarity can degrade the signal bymore than 20 dB. I seldom have
trouble hearing SO-50 as long asI keep up with the tumbling of the bird.
73/GL, Bob K8BL
Sent: Thursday, April 30, 2015 11:49 PM
Subject: [amsat-bb] What preamp to use for SO-50 and Arrow II antenna?
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
_______________________________________________
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
_______________________________________________
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

Bill ACITO, W1PA

2015-05-04 17:52:06 UTC

Permalink

Late, but...

I have an ARR (Advanced Receiver Research) 432 RF-switched
pre-amp hanging from the UHF side of my Arrow
with its own 12V NiMH pack.

I went "switched" in case I do something stupid.

I wear a mic-headset (YH2) and run the FT-530 in my right
hand, and hold the Arrow in my left.
I've rigged up patch cables that run HT audio (thru a 60db
pad) into one side of my stereo digital recorder,
and ambient audio (from a mic) into the other so I can
isolate what I said and what I heard. Some of my log
recordings are a great argument for full-duplex; e.g. I can
hear clearly and immediately if a letter got lost
and I need to repeat my grid a second time --- especially
running 5W. The FT530 does not de-sense and I can
clearly hear my own downlink in the headset.

With the pre-amp, clean sky and polarization match, SO-50 is
full scale into the FT-530 RX. Where it helps is
when I have trees and a less than optimal horizon (pretty
common in New England).

I ran the same on AO-51 and AO-27 and could copy right down
to the horizon, easily working into Europe.

Bill W1PA

_______________________________________________
Sent via AMSAT-***@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