December 2007 - AMSAT-BB - mailman.amsat.org

Compass Function in GPS
by James Duffey 29 Dec '07

29 Dec '07

Unless your GPS has a dedicated compass, the direction function, which appears to be a compass will only function when the unit is in motion. I found out this the hard way on my rove in the June VHF contest. - Duffey -- James Duffey KK6MC/5 Cedar Crest NM 87008 DM65

2 1

Re: Sun shadow for True North
by Dave Guimont 29 Dec '07

29 Dec '07

> >>A vertical rod about 4' long (plumb it, or use a level) will have the >>shortest shadow at noon. I should have said "near noon".....THE SH0RTEST SHADOW IS WHEN THE SUN IS DUE SOUTH OF YOU,NORTH IN YOUR CASE, No matter where you are with relation to the "clock".. Check sunrise and sunset, divide by 2, add to the sunrise, and will give you THE TIME WHEN THE SUN IS HIGHEST....FORGET WHERE YOU ARE IN YOUR TIME ZONE.... That n/s line will be 90° to the e/w line made with the markers....You don't need a watch, or care where you are in the world.... >Not necessarily. Ignoring DST, local solar noon >can occur anywhere within a window of around 1 >hour (give or take, depending on the exact >borders of your local time zone), because each >time zone is approximately 15 degrees wide >(there are local variations that take the >official zones beyond the 15 degree nominal >zones). For example, here in Melbourne, local >solar noon usually occurs around approximately >02:15 - 02:20 UTC (12:15 - 12:20 standard time >or 13:15 - 13:20 DST). In Brisbane, it occurs >before noon AEST, despite both cities being in >the same time zone. Using the "shortest shadow >at noon" method, you can have an error of up to >10 degrees (now THAT would ruin the performance >of your high gain antenna!). Here, it would be >around 4-5 degrees, if one was ignorant of the actual time of solar noon. > >The moving shadow to find the East - West line >is a much better and MUCH more accurate idea. > >73 de VK3JED >http://vkradio.com 73, Dave, WB6LLO dguimon1(a)san.rr.com Disagree: I learn.... Pulling for P3E...

1 0

visual sighting possible?
by Ollie Eisman 28 Dec '07

28 Dec '07

A few nights ago I was outside with my Arrow and HT working AO-51. During this time I noticed the faint glow of a satellite in the direction that I was pointing my antenna (no, I was not using a compass, sticks or GPS) :) The satellite drifted across the sky and matched what I was seeing on my computer's tracking program. I followed the satellite with my antenna and I continued to get a great signal from Echo. Given that I am at 6000 feet altitude and in a dark area, do you think I really saw our small friend? Ollie, AJ1O

1 0

mode J filter / Comet CF416c
by K & R Yoksh 28 Dec '07

28 Dec '07

Hello everyone, I'm planning to install a diplexer ahead of my 70cm mast-mount preamp soon, and was interested to know any tips or tricks before I buy a diplexer and climb the tower. I was planning to go the cheap route, and buy the $35 MFJ-916b sold by my local ham store, but read in the manual: "The MFJ-916B is designed for indoor use. If you use the MFJ-916B outdoors, it should only be used for short periods of time under good weather conditions. Do not use the duplexer outdoors when there is any kind of precipitation." After reading that, I'm considering spending a little extra and buying the Comet 416c that others have had good luck with. I had planned to mount the unit inside of a section of PVC pipe with a pipe cap glued on the top, and open at the bottom. A single U-bolt should attach the unit to the tower. Please reply with any suggestions, or perhaps you know of an unpublished sale going on somewhere? Thanks! Happy New Year to everyone on the list, and I hope we'll see P3e launched in 2008! 73, Kyle Yoksh K0KN Olathe, Kansas

3 2

TNC options?
by Kevin Hartley 28 Dec '07

28 Dec '07

Greetings & Happy Holidays to all, After a 3yr hiatus, (IC910 sold & packed away G3RUH dish & patch ant & down converter after AO-40 died - plus I moved from ZL-land to VE7-land which was a big distraction), I recently decided to get back into chasing birds. One of the deciding factors was my neighbour lost several big cedar trees in his back yard in last year's wind-storms and I gained 120 deg of unobstructed sky to the SW as a result! Re-joined AMSAT last month & signed up to the BBS to watch & learn now I have a question to ask. Hope to start with LEOS (i.e. Echo) and other easy-sats, to get my skill level up. Seems to be absence of VE7s on Vancouver Island to ask for help but I'm taking the plunge anyway! Ordered a IC-910 & 23cm module & UHF preamp as my Xmas present to myself, still waiting on Icom Canada to deliver, but soon! Starting out simple with an Arrow 2m/70cm antenna & a 23cm loop yagi at a fixed 40deg angle, on a cheap TV rotor, with some good info from Chip W7AIT who sent me all kinds of emails (thanks Chip!). My question is, I want to try packet/data on sats once the IC-910 arrives. Have an old AEA PK-900 1200b TNC on the shelf unused. Wondering if its a good idea to spend the $$ to get Timewave upgrades to give it 9600b capability? OR perhaps better to pick up a new KPC-9612PLUS for about the same $$? The brochure I read indicates the 9612 goes up to 34000 baud? Really? Or are there other off-the-shelf options I'm not aware of that are better? Want to give myself maximum flexibility for present & future birds on packet, but not too complex, a radio engineer I'm not. I've ordered the AMSAT Digital Sat handbook a month ago, along with some other books from the AMSAT store and they haven't arrived yet. But this is more a real-world type question where I'm looking for answers from people who've had experience with working sats and can recommend packet gear to buy or tncs to stay away from? Don't mind putting some time & effort into it, but an off-the-shelf solution would work best for me. Suggestions anyone? Hoping to be on the air soon from CN88! Thanks & 73, Kevin VE7OVY

4 3

Sun shadow for True North
by Dave Guimont 28 Dec '07

28 Dec '07

A vertical rod about 4' long (plumb it, or use a level) will have the shortest shadow at noon. Some one asked about waiting, for it to happen. Well don't. About an hour an a half before approximate noon (use standard time) put a mark of some sort. Then every half hour or so to increase the accuracy until ~1 1/2 hours after approximate noon standard time and you will have a true east west line....Construct from there.... You won't get the fraction degree accuracy someone mentioned with the north star, but I don't think you will need that.000009 db gain either unless you need a 30db antenna for your frequency!!! 73, Dave, WB6LLO dguimon1(a)san.rr.com Disagree: I learn.... Pulling for P3E...

1 0

Re: mode J filter / Comet CF416c
by Andrew Glasbrenner 28 Dec '07

28 Dec '07

-----Original Message----- >From: Ken Shutt <kgshutt(a)cox.net> >Kyle, > >I would recommend putting the preamp as close to the antenna as possible. >The diplexer should go between the radio and pre amp. If you are planning >to feed dc to the preamp on the coax, you need to make sure the diplexer >will pass the dc to the preamp. > >73 de Ken W5KQ Hi Ken, I think Kyle is wanting to use the diplexer as a high-pass filter in front of the preamp to prevent the 2m uplink signal from overloading the preamp, as explained at http://www.amsat.org/amsat-new/articles/Mode-J/ . 73, Drew KO4MA

1 0

DATA SOFTWARE
by Mr Jeffrey L Ross 28 Dec '07

28 Dec '07

FOLKS, ANYONE KNOW OF A SOFTWARE OUT THERE THAT WILL TELL ME WHAT MODE I AM RECEIVING? I HAVE A LITTLE EXPERIENCE WITH MIXW BUT WITH THAT YOU NEED TO KNOW WHAT MODE YOU WANT TO USE. OR ARE USING. I NEED SOMETHING THAT WILL TELL ME WHAT MODE IS THERE. ANY ADVISE WOULD BE HELPFULL, THANK YOU. KC8GKF P.S. LEARNING THE SOUNDS OF DATA, BUT WOW, SO MANY THERE ARE.

2 1

Re: 70cm yagi design (photos)
by Andrew Rich 28 Dec '07

28 Dec '07

One is done Photos here Up the pole she goes. http://www.tech-software.net/70cmyagi/index.html ---------------------------------------------------------------------------- Andrew Rich VK4TEC

3 4

Paint and RF
by Andrew Rich 28 Dec '07

28 Dec '07

Something just dawned on me. I have been painting the wooden booms of my antenna Does painting a boom affect it ? ---------------------------------------------------------------------------- Andrew Rich VK4TEC vk4tec(a)people.net.au http://www.tech-software.net

4 3