[amsat-bb] Re: Arrow and EME?
Idle-Tyme
nss at mwt.net
Thu Apr 1 12:31:31 PDT 2010
the best was neither vert or horizontal, and continously changing, well
slowly changing faraday rotation. plus why would you want to aste n
extra 3 db if you have it to be used?
Joe WB9SBD
The Original Rolling Ball Clock
Idle Tyme
Idle-Tyme.com
http://www.idle-tyme.com
On 4/1/2010 2:27 PM, Mark Lunday wrote:
> Would this also be accomplished in "poor man's design" by simply having one
> yagi vertical and one horizontal?
>
>
> Mark Lunday
> WD4ELG
> Greensboro, NC - FM06be
> wd4elg at arrl.net
> http://wd4elg.net
> http://wd4elg.blogspot.com
>
>
>
> -----Original Message-----
> From: amsat-bb-bounces at amsat.org [mailto:amsat-bb-bounces at amsat.org] On
> Behalf Of Idle-Tyme
> Sent: Thursday, April 01, 2010 1:53 PM
> To: amsat-bb at amsat.org
> Subject: [amsat-bb] Re: Arrow and EME?
>
> Another very important thing is polarity.
> the ability to change polarity can easily me a completed QSO or one
> where not a peep was heard.
>
> In the late 80's early 90's I had a small station of 4 eight element 2
> meter yagis. I think they were a W1JR design?
>
> anyway I mounted them in a way that i could rotate them in polarity also.
>
> It was amazing I never thought i could do moonbounce with them but just
> for kicks was listening down at the bottom of the band one day and heard
> someone CQing and wortking someone off he moon. of course it was W5UN.
> but a random call when he finished and we had a complete QSO in the log
> with no repeats solid exchange both ways!
>
> what make this amazing was I was using a kenwood TS700 rig into a old
> KLM (remember KLM amps?) a 70 watt one that was tired and only putting
> out about 35 watts, into a run of rg 213 50 feet to the antenna, no pre
> amps at all. and on CW by ear! no filters either just the standard 2.XX
> whatever wide filter.
> But the polarity made all the difference! In horizontal mode i heard
> NOTHING. but somewhere inbetween H and V he wa solid copy and he had no
> problem hearing me too.
>
> I eventually went on to work about 30 other stations as small as other 4
> yagi stations. The ability to make polarity changes is a GIANT advantage!
>
> Joe WB9SBD
>
> The Original Rolling Ball Clock
> Idle Tyme
> Idle-Tyme.com
> http://www.idle-tyme.com
>
> On 4/1/2010 12:11 PM, Mark Lunday wrote:
>
>> I have been doing some reading on this also. Although I have not yet made
>> any EME contacts, I have been uncovered the following:
>>
>> 1. Moonrise/moonset will enhance signals because of ground reflections,
>> something like 6 dB. Many folks intentionally use moonrise and moonset
>> attempts for this reason.
>>
>> 2. Mast mounted pre-amp is essential
>>
>> 3. Higher frequencies need more gain (so I have been told). But the 440
>>
> MHz
>
>> part of the arrow antenna should have a LOT more gain than the 2 meter
>>
> part.
>
>> 4. Low loss coax is very important, esp at VHF. Keep the runs short and
>>
> use
>
>> something equiv to LMR 400 (50 foot of the good stuff is probably under
>> $100, and worth it.
>>
>> 5. Definitely try to set up a sked with W5UN. If you can hear him, then
>>
> you
>
>> are halfway there!
>>
>> 6. Monitor websites like http://www.chris.org/cgi-bin/jt65emeA
>>
>> 7. 2010 appears to be a promising year for EME, here is a good calendar:
>> http://www.vhfdx.net/w5luu.html
>>
>>
>> Mark Lunday
>> WD4ELG
>> Greensboro, NC - FM06be
>> wd4elg at arrl.net
>> http://wd4elg.net
>> http://wd4elg.blogspot.com
>>
>>
>>
>> -----Original Message-----
>> From: amsat-bb-bounces at amsat.org [mailto:amsat-bb-bounces at amsat.org] On
>> Behalf Of MM
>> Sent: Thursday, April 01, 2010 8:37 AM
>> To: AMSAT-BB at amsat.org
>> Subject: [amsat-bb] Arrow and EME?
>>
>> Arrow Antenna and EME:
>>
>> It is possible to work Earth Moon Earth with an Arrow Antenna.
>>
>> Of course, it is. You just need to make a schedule with someone on the
>> other side of the link with enough Antenna Gain. You also need to be
>> running the new digital text messaging mode called JT65B
>>
>> Link for JT65
>> http://www.physics.princeton.edu/pulsar/K1JT/
>>
>> Definitions:
>> In this document I will refer to all antenna gain values based on the
>>
> number
>
>> of elements.
>>
>> Example: A Single half-wave Dipole = 0 dBd
>> Elements 2 = 3 dBd
>> Elements 4 = 6 dBd
>> Elements 8 = 9 dBd
>> Elements 16 = 12 dBd
>>
>> The Arrow antenna (Model 146/436-10) has 3 elements on the 2-meter band,
>>
> so
>
>> its maximum theoretical "Element Gain" is 4.5 dBd.
>>
>> With the invention of the JT65 protocols, thousands of Amateur Radio
>> stations running a Single Yagi 2-meter antennas, now have access to the
>>
> Moon
>
>> and EME contacts.
>>
>> To make a contact on Moon bounce, the "Total Antenna Gain" from both
>> stations is added up and will need to be in the approximate range of
>>
> 25-30
>
>> dBd. With this gain and the average transmitter power of (100-400 watts)
>> you will have a 10-20+ percent chance of completing a 2-way EME JT65B
>>
> link,
>
>> with another station.
>> Note: There are many other factures used in EME gain calculations. For
>> simplicity, we will just focus on the antenna Gain.
>>
>> The amount of Total Antenna Gain required depends on the mode you wish to
>> use. The wider the mode, the more gain that is required. The mode JT65B
>>
> is
>
>> a very narrow mode and requires less gain. I am not going to go over all
>>
> of
>
>> the details of JT65 in this article, look it up.
>>
>> Gain required by mode: (All values are approximate)
>>
>> JT65 28-30 dBd (1-Yagi + 4-Yagi)
>> CW 30-40 dBd (4-Yagi + 4-Yagi)
>> SSB 40-50 dBd (8-Yagi + 8-Yagi)
>> FM 60-70 dBd (16 + 24) Guess
>>
>>
>> The Mode JT65B requires approximately 30 dB of Total Antenna Gain for an
>>
> EME
>
>> contact.
>> If we assume the average 12-element 2-Meter Yagi has 10.5 dBd (round to 11
>> for easy math) of "Element Gain", then the more Yagi's you stack, the
>>
> more
>
>> gain you will have. In EME lingo, 1x12 means, you have One Yagi, with 12
>> elements, 4x12 means you have a stack of 4 yagis with 12 elements each
>>
> (48
>
>> elements total) and an approximate gain of 17 dBd.
>>
>> 1-Yagi = 11 dBd
>> 2-Yagi = 14 dBd
>> 4-Yagi = 17 dBd
>> 8-Yagi = 20 dBd
>> 16-Yagi = 23 dBd
>> 32-Yagi = 26 dBd
>> 64-Yagi = 29 dBd (W5UN)
>>
>>
>> A Single-Yagi station (11 dBd) calling a 4-Yagi (17 dBd) station will
>>
> have
>
>> approximately 28 dBd Total Antenna Gain. The 4xYagi stations are very
>> common on JT56B EME.
>>
>> Let's go back to the Arrow Antenna:
>>
>> We need 30 dBd of total antenna gain.
>> The Arrow antenna has 4.5 dBd.
>> The Arrow also has a Maximum power limitation of 150 watts (10 watts if
>>
> hand
>
>> held).
>>
>> If you are running the maximum 150 watts on your Arrow antenna, you
>>
> should
>
>> be able to work stations with 32 to 64 Yagi's. There are not very many 64
>> Yagi stations out there, however Dave W5UN has been active on JT65 EME
>> recently.
>>
>> If you want more of a challenge, you can try QRP at 5 watts and your Arrow
>> antenna.
>> Reducing you power from 150 watts to 5-10 watts, will reduce your
>> performance by 12 db.
>> To compensate for the reduce power, you will just need to find a station
>> with a bigger antenna.
>>
>> There is another big gun on EME. Two weeks ago, Arecibo was on EME,
>>
> running
>
>> CW, working EME stations on the 440 band. The antenna used at Arecibo is
>>
> a
>
>> simple 1,000 foot dish. The actual gain for 2-meters is not known,
>>
> however
>
>> I will assume it is more than 64-Yagi's.
>>
>> http://www.naic.edu/
>>
>> So here is your chance. Make a schedule with Arecibo and go for QRP, EME,
>> with a held Arrow antenna, or if you know of any good contacts at Arecibo,
>> send me the data and I'll try to arrange a schedule and try it from my
>> station.
>>
>> Other Hardware:
>> A good Receiver Preamp (similar to ARR)
>> http://www.advancedreceiver.com/
>>
>> A good SSB 2-meter Transceiver (the best ever made Yaesu FT-736R)
>> http://www.xs4all.nl/~ketel/ham/ft736.htm
>>
>> Good Coax (RG-8 coax is 11 Millimeter coax. That is ok for 50' EME runs,
>> for longer runs use 12+ Millimeter coax)
>>
>> 73
>>
>> WF1F
>> www.marexmg.org
>>
>>
>>
>>
>>
>>
>>
>>
>>
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>>
>>
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