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CX2SA > SATDIG 04.10.13 11:41l 1022 Lines 33713 Bytes #999 (0) @ WW
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Today's Topics:
1. Re: AMSAT Broadband Preamp Specs (Alan)
2. AMSAT Space Symposium (Martha)
3. Re: AMSAT Broadband Preamp Specs (Paul Stoetzer)
4. AMSAT Journal Call for Articles (JoAnne Maenpaa)
5. Re: AMSAT Broadband Preamp Specs (i8cvs)
6. Crushcraft A144-10T "VHF Twist" Antenna (Les Rayburn)
7. Re: AMSAT Broadband Preamp Specs (i8cvs)
8. Re: Crushcraft A144-10T "VHF Twist" Antenna (i8cvs)
9. Re: AMSAT Broadband Preamp Specs (Paul Stoetzer)
10. Re: Crushcraft A144-10T "VHF Twist" Antenna (Bill Bordy, NJ1H )
11. 2m--> 10.7Mhz downconverter (Andy Brian)
12. Re: 2m--> 10.7Mhz downconverter (M5AKA)
13. Re: AMSAT Broadband Preamp Specs (g0mrf@xxx.xxxx
----------------------------------------------------------------------
Message: 1
Date: Thu, 3 Oct 2013 15:26:54 -0500
From: Alan <wa4sca@xxxxx.xxx>
To: "'Paul Stoetzer'" <n8hm@xxxx.xxx>, <APBIDDLE@xxxxxxx.xxx>
Cc: amsat-bb@xxxxx.xxx
Subject: [amsat-bb] Re: AMSAT Broadband Preamp Specs
Message-ID: <F835EA221635417BAC5EC1E82F428CF9@xxxxxx>
Content-Type: text/plain; charset="us-ascii"
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:n8hm@xxxx.xxxx
<Sent: Thursday, October 03, 2013 11:02 AM
<To: APBIDDLE@xxxxxxx.xxx
<Cc: Alan; amsat-bb@xxxxx.xxx
<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-bounces@xxxxx.xxx
<> <[mailto:amsat-bb-bounces@xxxxx.xxxx On Behalf Of Paul Stoetzer
<> <Sent: Thursday, October 03, 2013 5:40 AM
<> <To: amsat-bb@xxxxx.xxx
<> <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@xxxxx.xxx. 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
<> <
<>
<
------------------------------
Message: 2
Date: Thu, 3 Oct 2013 16:39:08 -0400
From: Martha <martha@xxxxx.xxx>
To: AMSAT BB <amsat-bb@xxxxx.xxx>
Subject: [amsat-bb] AMSAT Space Symposium
Message-ID:
<CAPk0USyVp67fKVrDH3NyKCqRBdA0hOn1q_URz7x8=nBBpAUA6w@xxxx.xxxxx.xxx>
Content-Type: text/plain; charset=ISO-8859-1
If you are planning to attend this year's Space Symposium, please note that
the deadline for hotel reservations is October 16th. For more information,
check the website (amsat.org)
--
73- Martha
------------------------------
Message: 3
Date: Thu, 03 Oct 2013 17:24:57 -0400
From: Paul Stoetzer <n8hm@xxxx.xxx>
To: APBIDDLE@xxxxxxx.xxx
Cc: Alan <wa4sca@xxxxx.xxx>, amsat-bb@xxxxx.xxx
Subject: [amsat-bb] Re: AMSAT Broadband Preamp Specs
Message-ID: <524DE0A9.9010005@xxxx.xxx>
Content-Type: text/plain; charset=ISO-8859-1; format=flowed
Thanks, Alan.
I'm also on the FUNcube list and saw that link from a thread about this
very topic. I will likely give that a try at some point, though the
combination of 152 MHz notch filter, preamp, and 6 dB attenuator seemed
to do a very good job on the last pass of AO-7. I heard no evidence of
receiver desense, receive signal strength was still quite good, and I
copied the satellite quite well down to below 5 degrees to the north,
which is my worst direction. There is still quite a bit of noise, but
I'm afraid that's likely all broadband noise.
73,
Paul, N8HM
On 10/3/2013 4:26 PM, Alan wrote:
> 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:n8hm@xxxx.xxxx
> <Sent: Thursday, October 03, 2013 11:02 AM
> <To: APBIDDLE@xxxxxxx.xxx
> <Cc: Alan; amsat-bb@xxxxx.xxx
> <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-bounces@xxxxx.xxx
> <> <[mailto:amsat-bb-bounces@xxxxx.xxxx On Behalf Of Paul Stoetzer
> <> <Sent: Thursday, October 03, 2013 5:40 AM
> <> <To: amsat-bb@xxxxx.xxx
> <> <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@xxxxx.xxx. 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
> <> <
> <>
> <
>
------------------------------
Message: 4
Date: Thu, 3 Oct 2013 17:49:29 -0500
From: "JoAnne Maenpaa" <k9jkm@xxxxxxx.xxx>
To: <amsat-bb@xxxxx.xxx>
Subject: [amsat-bb] AMSAT Journal Call for Articles
Message-ID: <008001cec08a$d21f0070$765d0150$@xxx>
Content-Type: text/plain; charset="us-ascii"
The AMSAT Journal is continuously searching for news, articles,
and photos related to all of the activities of amateur radio
in space. In the past this has included satellite development,
satellite history, ground stations, antennas, hardware devel-
opment, software. We find that some items related to SDR, VHF,
UHF, and microwave operating or roving are directly applicable
to satellite operations.
Educational outreach has been identified as a key area which AMSAT
may use to leverage launch opportunities. The Journal welcomes
news, photos, and articles of ARISS contacts, University research
and development, and STEM programs.
Amateur satellite operators have the gear and expertise to also
receive interesting transmissions from non-amateur spacecraft and
EME. Articles discussing how this is done are useful to our readers
discovering they can do more with the station they have built.
The deadlines for each AMSAT Journal, which is published six times
per year, are:
ISSUE DEADLINE
--------------------- --------------
1. January/February December 20
2. March/April February 20
3. May/June April 20
4. July/August June 20
5. September/October August 20
6. November/December October 20
Our editors will work with you to finalize your article for publi-
cation. Please send the following:
1. Electronic copy of your article in any of the popular word pro-
cessing formats (MS-Word, OpenOffice, plain-text Notepad, etc.)
PDF files containing a custom layout with embedded graphics can-
not be used.
2. Your text must be single column wide. You do not need to do any
formatting to make it appear in the 3 column layout of the fin-
ished magazine. We have to remove all your hard work of pre-
formatting before publication so save yourself the problems of
trying to get columns to line up, etc.
3. You may send a copy of your article with the photos where you
recommend they appear with the text but this is not the version
that will be published. This gives the editors some cues to
maintain continuity with photos/captions and text.
4. We require a text-only copy your article. Embedded photos will
not publish during the layout process. You can leave in a ref-
erence in the text related to the photo associated with that
point in your article as shown here:
... text ... text ... text ... text ... text ... text ...
... text ... text ... text ... text ... text ... text ...
(Insert Graphic 1234 here)
Figure 2. Sample Lorem Ipsum Text
... text ... text ... text ... text ... text ... text ...
... text ... text ... text ... text ... text ... text ...
5. Send a separate text file with the captions to each of the
graphics.
6. Send photos and graphics as separate files. Use as high resolu-
tion pixel format as you can. The preferred graphic format for
the Journal is JPG.
The Journal can publish additional graphic formats including
GIF, BMP, and PNG. Contact the editor before submitting these
formats.
Note that a photo which appears nicely on a web page does not
publish well on the high resolution finished magazine product.
Photos from digital cameras in mega-pixels work well. You do
not need to compress or shrink the file for us.
7. If you use printed circuit board software or schematic drawing
programs we can usually import a PDF copy of the diagram into
the publishing software. Please do not send PDF formatted copies
of the article however.
8. We can freely republish papers you have submitted to prior AMSAT
Symposiums. If you have a good idea that you would like to get
out the AMSAT Journal is an excellent way to expand your audience.
We find that 200-300 copies of the Symposium Proceedings are dis-
tributed. The AMSAT Journal reaches 4000 additional satellite
operators.
9. If your article was previously published in another AMSAT organi-
zation's Journal, or magazine (QST, CQ, CQ VHF, etc.) we will
work with you to secure the permission to republish your work.
Our Journal editors will be happy to work with you to assist getting
your article published. We can help you develop an idea into a fin-
ished article as well as a ready-to-print submission. Ask us via
e-mail and we can get rolling with your article.
During the preparation process it is quite likely that an editor
working on the article might personally contact you with questions
and suggestions. Those suggestions might include extra pictures or
maybe additional references, keeping in mind that some readers
might not have an extensive background on the topic being discussed.
Send your articles and photo/graphics files as attachments to
e-mail to journal@xxxxx.xxx.
--
73 de JoAnne K9JKM
k9jkm@xxxxx.xxx
Editor, AMSAT Journal
------------------------------
Message: 5
Date: Fri, 4 Oct 2013 03:38:21 +0200
From: "i8cvs" <domenico.i8cvs@xxx.xx>
To: "Paul Stoetzer" <n8hm@xxxx.xxx>, "AMSAT-BB" <amsat-bb@xxxxx.xxx>
Subject: [amsat-bb] Re: AMSAT Broadband Preamp Specs
Message-ID: <005101cec0a2$6b485320$0301a8c0@xxxxx>
Content-Type: text/plain; charset="iso-8859-1"
Hi Paul, N8HM
I can measure the Noise Figure and Gain of any preamplifier using
my PANFI (Precision Automatic Noise Figure Indicator ) up to
12.5 GHz but unfortunately I don't know any one in Italy close to
my QTH that own the AMSAT preamplifier.
If someone in Italy has the AMSAT preamplifier I can made the
measurement and send back the stuff back to him giving publicity
of the results to you and the others via AMSAT-BB
73" de
i8CVS Domenico
----- Original Message -----
From: "Paul Stoetzer" <n8hm@xxxx.xxx>
To: <amsat-bb@xxxxx.xxx>
Sent: Thursday, October 03, 2013 12:40 PM
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@xxxxx.xxx. 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
------------------------------
Message: 6
Date: Thu, 03 Oct 2013 21:18:53 -0500
From: Les Rayburn <les@xxxxxxxxxxxx.xxx>
To: AMSAT Mailing List <amsat-bb@xxxxx.xxx>, starcom-bb@xxxxxxxx.xxx
Subject: [amsat-bb] Crushcraft A144-10T "VHF Twist" Antenna
Message-ID: <524E258D.2000703@xxxxxxxxxxxx.xxx>
Content-Type: text/plain; charset=ISO-8859-1; format=flowed
I just acquired a "new" in the-box, never assembled Crushcraft A144-10T
"VHF Twist" antenna. It includes the cabling to allow the user to select
left or right hand polarization. My questions are numerous:
1.) How is the performance on this antenna, compared to more modern
designs?
2.) If I were going to install it inside my attic, should I chose left
or right hand polarization?
3.) Any caveats or things to watch out for?
Any information that could be provided would be great. I was thrilled
when a friend stopped by and asked me if I'd be interested in the
antenna. Good price too.
--
--
73,
Les Rayburn, N1LF
121 Mayfair Park
Maylene, AL 35114
EM63nf
6M VUCC #1712
AMSAT #38965
Grid Bandits #222
Southeastern VHF Society
Central States VHF Society Life Member
Six Club #2484
Active on 6 Meters thru 1296, 10GHz & Light
------------------------------
Message: 7
Date: Fri, 4 Oct 2013 05:06:46 +0200
From: "i8cvs" <domenico.i8cvs@xxx.xx>
To: "Paul Stoetzer" <n8hm@xxxx.xxx>, <APBIDDLE@xxxxxxx.xxx>,
<wa4sca@xxxxx.xxx>, "AMSAT-BB" <amsat-bb@xxxxx.xxx>
Subject: [amsat-bb] Re: AMSAT Broadband Preamp Specs
Message-ID: <001301cec0ae$c626d800$0301a8c0@xxxxx>
Content-Type: text/plain; charset="iso-8859-1"
----- Original Message -----
From: "Paul Stoetzer" <n8hm@xxxx.xxx>
To: <APBIDDLE@xxxxxxx.xxx>
Cc: "Alan" <wa4sca@xxxxx.xxx>; <amsat-bb@xxxxx.xxx>
Sent: Thursday, October 03, 2013 6:02 PM
Subject: [amsat-bb] Re: 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).
>
> 73,
>
> Paul, N8HM
Hi Paul, N8HM
Just for your information the sensitivity of the ICOM IC-R10 in CW
and SSB is :
144 MHz: 0.25 uV for a S/N ratio of 10 dB
435 MHz: 0.32 uV for a S/N ratio of 10 dB
To convert the above sensitivity in Noise Figure (NF) you can use the
folloving formula:
-6 2
( Vi x 10 ) x 20
NF = 10 log [ ------------------------ ] +174
dB 10 BW x S/N
where:
Vi = input signal in uV applied over the 50 ohm RX input
BW = Band Wide in Hz (2400 Hz for SSB)
S/N = Signal to Noise ratio in power ratio = 10
Back to arithmetic and using a scientific pocket calculator you
get the following results:
144 MHz NF = 11.2 dB
435MHz NF = 13.3 dB
The above NF are very high and to overcome only part of
your problems ignoring all interference in your QTH that
requires sharp notch filtering you need front end preamplifiers
with at least the following characteristic:
144 MHz : NF= 0.6 dB and gain G = 20 dB with a very high
third order intercept point IP3 and very high 1 dB compression
point like a preamplifiers of the Norton type circuit.
435 MHz : NF = 0.5 dB and gain G 20 dB possibly with
cavity input circuit like that described in my article publisched
recently into the AMSAT Journal March/April 2013
I hope this helps.
73" de i8CVS Domenico
------------------------------
Message: 8
Date: Fri, 4 Oct 2013 05:39:45 +0200
From: "i8cvs" <domenico.i8cvs@xxx.xx>
To: "AMSAT-BB" <amsat-bb@xxxxx.xxx>, <starcom-bb@xxxxxxxx.xxx>,
<les@xxxxxxxxxxxx.xxx>
Subject: [amsat-bb] Re: Crushcraft A144-10T "VHF Twist" Antenna
Message-ID: <004101cec0b3$5f629be0$0301a8c0@xxxxx>
Content-Type: text/plain; charset="iso-8859-1"
----- Original Message -----
From: "Les Rayburn" <les@xxxxxxxxxxxx.xxx>
To: "AMSAT Mailing List" <amsat-bb@xxxxx.xxx>; <starcom-bb@xxxxxxxx.xxx>
Sent: Friday, October 04, 2013 4:18 AM
Subject: [amsat-bb] Crushcraft A144-10T "VHF Twist" Antenna
> I just acquired a "new" in the-box, never assembled Crushcraft A144-10T
> "VHF Twist" antenna. It includes the cabling to allow the user to select
> left or right hand polarization. My questions are numerous:
>
> 1.) How is the performance on this antenna, compared to more modern
> designs?
Hi Les,N1LF from Domenico, i8CVS
1) I have used the A144-10T since 1973 and compared to modern
type it works no so well because the phasing harness to switch
polarizations uses crimped PL connectors and you get water and
humidity into it.
>
> 2.) If I were going to install it inside my attic, should I chose left
> or right hand polarization?
2) To switch between RHCP and LHCP you must screw and unscrew
by hand the phasing harness connectors and since the antenna is not
equipped with a polarization switching relay you have not the time
to switch polarization while operating the satellite.
>
> 3.) Any caveats or things to watch out for?
>
3) Do not use the above Cushcraft A144-20 T for the above reason.
Buy a modern model of crossed yagi with polarization switching
relay between RHCP to LHCP possibly from 2M
> Any information that could be provided would be great. I was thrilled
> when a friend stopped by and asked me if I'd be interested in the
> antenna. Good price too.
>
>
I understand a good price because it is a old model of antenna
wich designe is almost back 30 yars ago. BTW the aluminum is
a good quality and witstand on the environment for many years.
> --
> 73,
>
> Les Rayburn, N1LF
> 121 Mayfair Park
> Maylene, AL 35114
> EM63nf
>
> 6M VUCC #1712
> AMSAT #38965
> Grid Bandits #222
> Southeastern VHF Society
> Central States VHF Society Life Member
> Six Club #2484
>
> Active on 6 Meters thru 1296, 10GHz & Light
73" de i8CVS Domenico
------------------------------
Message: 9
Date: Fri, 04 Oct 2013 00:15:43 -0400
From: Paul Stoetzer <n8hm@xxxx.xxx>
To: i8cvs <domenico.i8cvs@xxx.xx>
Cc: AMSAT-BB <amsat-bb@xxxxx.xxx>
Subject: [amsat-bb] Re: AMSAT Broadband Preamp Specs
Message-ID: <524E40EF.8070503@xxxx.xxx>
Content-Type: text/plain; charset=ISO-8859-1; format=flowed
Domenico,
Thanks for doing the math. It looks like the AR2 P144VDG and P432VDG
would be the preamps to try. I'd still need some good bandpass
filtering, of course, so this is a somewhat expensive proposition. It
also becomes unwieldy since I have to operate portable. The Icom IC-R10
does not have a robust front end and that much preamp gain is probably
going to cause problems. Already, with the AMSAT preamp, I need to add
6dB of attenuation to prevent the receiver from overloading. No idea
what that does to the overall noise figure of the system, but I seem to
have a better SNR on the signals with the attenuator in line.
My receive system is:
Arrow 3 element beam for 2m / 7 elements on 70cm > 1.83m of RG-58 > an
MFJ diplexer > 0.15m of RG-58 > PAR VHF DN152 notch filter > 0.15m of
RG-58 > AMSAT preamp > 0.9m of RG-58 > (6dB attenuator on 2m) > receiver
I probably don't need to keep the diplexer in line on 2m (it's there to
eliminate desense on Mode J) nor the notch filter in line on 70cm, but
it makes it much easier to switch between Mode B and Mode J to do so.
At this point, I'll probably just have to accept what I have. No
filtering is going to get rid of the broadband noise and no preamps can
overcome the geometry of an urban area.
However, If anyone has some suggestions for a low cost way to improve
this system, I'm all ears. Keep in mind that since I go outside for each
pass, all the gear has to fit inside a DSLR bag (see my QRZ.com page for
a picture).
73,
Paul Stoetzer, N8HM
On 10/3/2013 11:06 PM, i8cvs wrote:
> ----- Original Message -----
> From: "Paul Stoetzer" <n8hm@xxxx.xxx>
> To: <APBIDDLE@xxxxxxx.xxx>
> Cc: "Alan" <wa4sca@xxxxx.xxx>; <amsat-bb@xxxxx.xxx>
> Sent: Thursday, October 03, 2013 6:02 PM
> Subject: [amsat-bb] Re: 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).
>>
>> 73,
>>
>> Paul, N8HM
>
> Hi Paul, N8HM
>
> Just for your information the sensitivity of the ICOM IC-R10 in CW
> and SSB is :
>
> 144 MHz: 0.25 uV for a S/N ratio of 10 dB
> 435 MHz: 0.32 uV for a S/N ratio of 10 dB
>
> To convert the above sensitivity in Noise Figure (NF) you can use the
> folloving formula:
> -6 2
> ( Vi x 10 ) x 20
> NF = 10 log [ ------------------------ ] +174
> dB 10 BW x S/N
>
> where:
>
> Vi = input signal in uV applied over the 50 ohm RX input
> BW = Band Wide in Hz (2400 Hz for SSB)
> S/N = Signal to Noise ratio in power ratio = 10
>
> Back to arithmetic and using a scientific pocket calculator you
> get the following results:
>
> 144 MHz NF = 11.2 dB
> 435MHz NF = 13.3 dB
>
> The above NF are very high and to overcome only part of
> your problems ignoring all interference in your QTH that
> requires sharp notch filtering you need front end preamplifiers
> with at least the following characteristic:
>
> 144 MHz : NF= 0.6 dB and gain G = 20 dB with a very high
> third order intercept point IP3 and very high 1 dB compression
> point like a preamplifiers of the Norton type circuit.
>
> 435 MHz : NF = 0.5 dB and gain G 20 dB possibly with
> cavity input circuit like that described in my article publisched
> recently into the AMSAT Journal March/April 2013
>
> I hope this helps.
>
> 73" de i8CVS Domenico
>
------------------------------
Message: 10
Date: Fri, 04 Oct 2013 00:22:56 -0400
From: "Bill Bordy, NJ1H " <nj1h@xxxxxxx.xxx>
To: les@xxxxxxxxxxxx.xxxx AMSAT Mailing List <amsat-bb@xxxxx.xxx>
Subject: [amsat-bb] Re: Crushcraft A144-10T "VHF Twist" Antenna
Message-ID: <524E42A0.2030308@xxxxxxx.xxx>
Content-Type: text/plain; charset=ISO-8859-1; format=flowed
I have a Cushcraft A144-20T. Twice as many elements in each plane than
yours. I run both a vertical and horizontal coax to my shack and use a
crossover coax switch with phasing and impedance matching coax to
generate switchable circular polarization in the shack. Works great for
me. The polarization change makes a big difference at times on the
satellites..
I can also run just vertical or horizontal polarization by changing the
coax configuration in the shack. In fact, you can use the same crossover
switch as a SPDT to experiment with changing between horizontal and
vertical polarization. I do this during VHF contests sometimes. I have
also worked meteor scatter with it.
I have been using this antenna for 25 years with no problems. I used it
with AO10, AO13 and AO40 with no problems. The low orbit birds are
really loud compared to the high orbits birds.
73,
Bill
NJ1H
On 10/3/2013 10:18 PM, Les Rayburn wrote:
> I just acquired a "new" in the-box, never assembled Crushcraft
> A144-10T "VHF Twist" antenna. It includes the cabling to allow the
> user to select left or right hand polarization. My questions are
> numerous:
>
> 1.) How is the performance on this antenna, compared to more modern
> designs?
>
> 2.) If I were going to install it inside my attic, should I chose left
> or right hand polarization?
>
> 3.) Any caveats or things to watch out for?
>
> Any information that could be provided would be great. I was thrilled
> when a friend stopped by and asked me if I'd be interested in the
> antenna. Good price too.
>
>
------------------------------
Message: 11
Date: Fri, 4 Oct 2013 06:45:18 +0200
From: Andy Brian <briaandy@xxxxx.xxx>
To: AMSAT-BB <amsat-bb@xxxxx.xxx>
Subject: [amsat-bb] 2m--> 10.7Mhz downconverter
Message-ID:
<CADMEjK8Q9OU09spwi=p0Qqsn_jtM=R1Mddpv2=zj52MRzLHgSA@xxxx.xxxxx.xxx>
Content-Type: text/plain; charset=ISO-8859-1
Hi,
I need help to find any good design for the 2m to 10.7MHz downconverter
which I'll try to use for presentation linear transverter.
Please if you have any or point me to any good books where to find?
Thanks for all answers,
BR Andy
------------------------------
Message: 12
Date: Fri, 4 Oct 2013 08:23:57 +0100 (BST)
From: M5AKA <m5aka@xxxxx.xx.xx>
To: AMSAT-BB <amsat-bb@xxxxx.xxx>
Subject: [amsat-bb] Re: 2m--> 10.7Mhz downconverter
Message-ID:
<1380871437.78892.YahooMailNeo@xxxxxxxxx.xxxx.xxx.xxxxx.xxx>
Content-Type: text/plain; charset=iso-8859-1
> I need help to find any good design for the 2m to 10.7MHz downconverter
> which I'll try to use for presentation linear transverter.
While not 10.7 MHz you may find the circuit diagrams of the 145/29 MHz
linear transponders for the RS series of satellites of interest.
They are on the RadioSkaf website at http://tinyurl.com/RadioSkaf
- Click on the Forum menu option
- Under? Satellite "Radioskaf" select the Transmitter topic
- Then click on Schemes of repeaters
There are a number of circuit diagrams there available for download as JPEGs
Also see the Receiver -> Receiver CL (Command Radio Link) section
73 Trevor M5AKA
------------------------------
Message: 13
Date: Fri, 4 Oct 2013 05:33:06 -0400 (EDT)
From: g0mrf@xxx.xxx
To: domenico.i8cvs@xxx.xxx amsat-bb@xxxxx.xxx
Subject: [amsat-bb] Re: AMSAT Broadband Preamp Specs
Message-ID: <8D08EFBDD20E025-2DC-54975@xxxxxxxxxxxx.xxxxxx.xxx.xxx>
Content-Type: text/plain; charset="us-ascii"
Hi Domenico.
Thank you for that formula relating sensitivity in a particular bandwidth to
system noise figure.
I have lost count over the years of the number of times you've posted just
the right piece of theory to answer a question.
Definitely time to say....
Thank you.
David G0MRF
-----Original Message-----
From: i8cvs <domenico.i8cvs@xxx.xx>
To: Paul Stoetzer <n8hm@xxxx.xxx>; APBIDDLE <APBIDDLE@xxxxxxx.xxx>; wa4sca
<wa4sca@xxxxx.xxx>; AMSAT-BB <amsat-bb@xxxxx.xxx>
Sent: Fri, Oct 4, 2013 4:24 am
Subject: [amsat-bb] Re: AMSAT Broadband Preamp Specs
----- Original Message -----
From: "Paul Stoetzer" <n8hm@xxxx.xxx>
To: <APBIDDLE@xxxxxxx.xxx>
Cc: "Alan" <wa4sca@xxxxx.xxx>; <amsat-bb@xxxxx.xxx>
Sent: Thursday, October 03, 2013 6:02 PM
Subject: [amsat-bb] Re: 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).
>
> 73,
>
> Paul, N8HM
Hi Paul, N8HM
Just for your information the sensitivity of the ICOM IC-R10 in CW
and SSB is :
144 MHz: 0.25 uV for a S/N ratio of 10 dB
435 MHz: 0.32 uV for a S/N ratio of 10 dB
To convert the above sensitivity in Noise Figure (NF) you can use the
folloving formula:
-6 2
( Vi x 10 ) x 20
NF = 10 log [ ------------------------ ] +174
dB 10 BW x S/N
where:
Vi = input signal in uV applied over the 50 ohm RX input
BW = Band Wide in Hz (2400 Hz for SSB)
S/N = Signal to Noise ratio in power ratio = 10
Back to arithmetic and using a scientific pocket calculator you
get the following results:
144 MHz NF = 11.2 dB
435MHz NF = 13.3 dB
The above NF are very high and to overcome only part of
your problems ignoring all interference in your QTH that
requires sharp notch filtering you need front end preamplifiers
with at least the following characteristic:
144 MHz : NF= 0.6 dB and gain G = 20 dB with a very high
third order intercept point IP3 and very high 1 dB compression
point like a preamplifiers of the Norton type circuit.
435 MHz : NF = 0.5 dB and gain G 20 dB possibly with
cavity input circuit like that described in my article publisched
recently into the AMSAT Journal March/April 2013
I hope this helps.
73" de i8CVS Domenico
_______________________________________________
Sent via AMSAT-BB@xxxxx.xxx. 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@xxxxx.xxx. Opinions expressed are those of the author.
Not an AMSAT member? Join now to support the amateur satellite program!
http://amsat.org/mailman/listinfo/amsat-bb
End of AMSAT-BB Digest, Vol 8, Issue 339
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