[amsat-bb] Falconsat-3 Test 2 (turnstyles and amps)

Thu Oct 12 17:59:28 UTC 2017

LNA Preamps by all means are required.

But I am curious. It would seem that the turnstyle cannot have any more
gain than a simple dipole (2.3 dBi) circular, but broadside to each
dipole, it should have a net -0.7 dbi  since one dipole is contributing
nothing and power is split - 3dB between them.

Yes, it gives 2.3 dbi circular polarization gain overhead which reduces
fading, but has little gain in the quadrant directions.  An infinite
reflector can gain another 3 dB but this is not achieved with a simple
reflector element.

On the other hand, a vertical 1/4 wave doesn't do any better.  But if the
vertical is made 3/4 waves long, (about 20" tall for UHF) and is placed
over a good sized ground plane, then the gain is over 7 dBi above about 30
degrees.

That's the good news, but the bad news is that Sateliltes only spend about
30% of their total time in view above about 22 degrees as shown on this
page: http://aprs.org/LEO-tracking.html

But the high elevation gain of the simple 3/4 wave vertical above 30
degrees is shown about 80% down this very long page:
http://aprs.org/astars.html

As an old fud, I hold to this firmly held belief about the same as other
old fud's cling to theirs, so I hope someday to actually make some real
comparisions instead of just talking about it.

But here is my bottom line,  Turnstyles and egg beaters (in my opinion)
are excellent omni directional cross polarized antennas for satellite
work... but equally poor in all directions.  In other words, they
sacrifice gain when the satellite is higher and much close, for gain at
the horizon where they can never possibly hear a weak satellite anway.

So I like the reverse.  Sacrificing gain at the horizon, where I can't
hear them anyway, for higher gain higher up when they are closer and give
a 5 dB stronger signal.

So for a simple quick test, put up a 19" quarter wave whip over a ground
plane and it will give you 5 dBi gain on VHF above about 15 degrees and 7
dBi gain on UHF above about 20 degrees.

Your mileage may vary.
Bob, WB4APR

-----Original Message-----
From: AMSAT-BB [mailto:amsat-bb-bounces at amsat.org] On Behalf Of Andrew
Rich
Sent: Thursday, October 12, 2017 7:08 AM
To: Dave Webb KB1PVH
Cc: AMSAT -BB
Subject: Re: [amsat-bb] [OZAPRS] Falconsat-3 Test 2 - Signalink USB Sound
Card 9k6

Roger that

Turnstiles and amps underway

Could not find anyone willing to send me 9k6 locally I would have seen
that

A

Sent from my iPhone

> On 12 Oct 2017, at 8:46 pm, Dave Webb KB1PVH <kb1pvh at gmail.com> wrote:
>
> Andrew,
>
>  You need a pretty decent signal with 9600 to be able to decode and
> your
> X300 vertical isn't going to cut it for satellite work.
>
> Dave-KB1PVH
>
>
> Sent from my Galaxy S7
>
>> On Oct 12, 2017 6:40 AM, "Andrew Rich" <vk4tec at tech-software.net>
wrote:
>>
>> Rick
>>
>> What antenna preamp are you using
>>
>> And what signal strength do you get
>>
>> Andrew
>>
>> Sent from my iPhone
>>
>>> On 12 Oct 2017, at 4:54 pm, Rick Kowalewski <rick at vk6xlr.net> wrote:
>>>
>>> Sure it can:
>>>
>>> Here's copied data from a few days ago:
>>> 1:Fm PFS3-1 To TLMC-1 <UI R Pid=F0 Len=4> [20:56:49R] [AA]
>>> [+--++--]CL:0 1:Fm PFS3-1 To LSTAT <UI R Pid=F0 Len=46> [20:56:49R]
>>> [AA] [---+---]I
>> P:0x13A8 o:0 l:26062 f:26092, d:1 st:6 e:cb
>>> 1:Fm PFS3-1 To TIME-1 <UI R Pid=F0 Len=64> [20:56:58R] [AN]
>> [-------]PHT: uptime is 707/07:49:24.  Time is Fri Oct 06 12:57:53
>> 2017
>>> 1:Fm PFS3-11 To PBLIST <UI R Pid=F0 Len=11> [20:59:01R] [NN]
>> [+--+---]PB: Empty.
>>>
>>>> On 12/10/2017 14:29, Andrew Rich wrote:
>>>> ICOM 910H
>>>>
>>>> 9k6 ON
>>>>
>>>> Signalink with UZ7HO sound modem FSM G3RUH 9600 baud
>>>>
>>>> Elevation 89.4 degrees
>>>>
>>>> MacDoppler correction 435.112 MHz to 435.xxx MHz
>>>>
>>>> No Packets copied
>>>>
>>>> 435.112 MHz Start heard a change in static
>>>>
>>>> I am not convinced the SignalLink can do it
>>>>
>>>> I am going to move across to a my FunCube Dongle and use Software
>> Defined Radio to try and snag it
>>>>
>>>> Will report back
>>>>
>>>> I can certainly hear the 9k6 rush from the bird
>>>>
>>>> Diamond X300 BS antenna LDF4-50
>>>>
>>>> Andrew VK4TEC
>>>
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Not an AMSAT-NA member? Join now to support the amateur satellite program!
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